Are you running into issues with your combi boiler? Read our guide on common combi boiler problems and how to fix them to restore order to your home.

<p><a href="https://www.boxt.co.uk/boilers/combi-boilers" rel="follow">Combi boilers</a>, sometimes known as combination boilers, are among the most popular home heating systems in the UK. They&rsquo;re energy-efficient, affordable, and compact, making them ideal for large numbers of households nationwide. &nbsp;</p>
<p>Combi boilers offer a wealth of advantages, but like any appliance, they are susceptible to the odd mishap.</p>
<p>If your home's boiler or central heating system isn&rsquo;t working as it should, it can feel like the end of the world, but don&rsquo;t worry&mdash;help is at hand.</p>
<p>In this guide, we&rsquo;ll help you troubleshoot some of the most common combi boiler problems so that you or your engineer can get things back up and running as soon as possible.</p>
<h2>The most common combi boiler problems</h2>
<p>Below are some of the combi boiler problems our engineers often encounter.&nbsp;</p>
<p>In most cases you will need to contact a Gas Safe registered engineer who&rsquo;ll be able to come and investigate.</p>

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<h3>No hot water</h3>
<p>Finding yourself without hot water is one of the most common (but most irritating) combi boiler issues people encounter. This can present itself in a few different ways, which we'll go through below.</p>
<h4>1. There is no hot water, but the central heating is working</h4>
<p>Sometimes, your home's central heating will work as usual, but hot water won&rsquo;t come from your taps.&nbsp;</p>
<p>In this scenario, The two things listed below, amongst many others, could be causing this problem.&nbsp;</p>
<ul>
<li><strong>Faulty diverter valve</strong>: In a combi boiler, the diverter valve directs hot water to the taps or the central heating system. If the valve isn&rsquo;t working as it should, it may not switch to the hot water mode when required.</li>
<li><strong>Scale/magnetite buildup</strong>: Over time, the accumulation of scale or magnetite in a combi boiler&rsquo;s plate heat exchanger could restrict or even block the flow of water through it, which would cause the boiler not to produce hot water and potentially overheat.</li>
</ul>
<p>For any of the potential causes listed above, you must <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe registered engineer</a> to come and take a look.</p>
<h4>2. There is no hot water and no central heating</h4>
<p>Here are some likely causes of no hot water or central heating in your home:</p>
<ul>
<li>Loss of water pressure: A considerable loss of water pressure in the system can prevent the boiler from operating for both hot water and central heating. If there isn&rsquo;t enough water, it won&rsquo;t be circulating in the home and safety devices in modern boilers will prevent it from lighting to protect the boiler.</li>
<li>Faulty programmer or timer switch: A malfunctioning programmer or timer switch may not signal the thermostats or boiler to produce hot water or activate the central heating.</li>
<li>Ignition issue: Problems with the boiler's ignition system or electronic controls can prevent it from firing up for hot water or heating.</li>
</ul>
<p>To resolve these issues, you can try a manual reset by following the manufacturer&rsquo;s instructions or&nbsp;<a href="https://www.boxt.co.uk/boilers/guides/boiler-pressure" rel="follow">repressurising your boiler</a>. If neither of these fixes gets things back up and running, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe registered engineer</a>, who can investigate further.</p>
<h4>3. There is hot water, but only when the heating is on</h4>
<p>If your combi boiler only produces hot water when the heating is on simultaneously, there will likely be an error.</p>
<p>Here are the main ones to look out for:</p>
<ul>
<li>Faulty diverter valve: As mentioned, this valve directs hot water to the heating system or the domestic hot water supply, depending on the user's selection. If the diverter valve is faulty or stuck, it may not move into the hot water position when required.</li>
<li>Faulty thermistor: If it is defective or malfunctioning, it can impact the boiler's ability to produce and deliver hot water on demand.</li>
</ul>
<p>Unfortunately, neither of these are DIY fixes. Contact a Gas Safe registered engineer to ensure your combi boiler&rsquo;s fault is investigated and repaired safely.&nbsp;</p>
<h3>Water leaking</h3>
<p>If your combi boiler leaks, you might first notice a drop in the water pressure in your system. When you look at the combi boiler, you might see a puddle forming or a stain beneath the appliance where water has gathered and dried.</p>
<p>Leaking water can indicate that internal components within the boiler are damaged and need replacing, such as the boiler's hydraulic blocks, O rings, seals and gaskets. Alongside this, leaking water out of your blow off pipe outside could mean you have a faulty pressure relief valve or issues with your boiler&rsquo;s expansion vessel.</p>
<p>If water is leaking from your boiler, the whole system must be inspected. These repairs are technical and can require specialist equipment, meaning you must <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe registered engineer</a> rather than trying to carry them out yourself.</p>
<h3>No pilot light</h3>
<p>If you have an older combi boiler that fails to ignite or shows signs of intermittent heating, there may be an issue with the pilot light. You can sometimes see your pilot light from outside your combi boiler via a sight glass.&nbsp;</p>
<p>The boiler's pilot light could be struggling to light for several reasons, including an issue with the gas supply or a blocked/dirty pilot burner assembly.</p>
<p>A Gas Safe registered engineer must investigate any combi boiler issues relating to gas supplies or faulty ignitions.&nbsp;</p>
<h3>Thermostat error</h3>
<p>If your combi boiler isn't responding to changes you're making on your room thermostat, there could be an error with your home's wireless network, or if you have a hard-wired thermostat, the thermostat itself could be faulty. Another telltale sign of a thermostat error is inaccurate temperature readings from the system and uneven heat distribution around the home.</p>
<p>The causes of a thermostat error can be things like incorrect wiring, signal loss, or boiler control board issues.</p>
<p>Here are some simple solutions that might help:</p>
<ul>
<li>Check the batteries if the thermostat is wireless</li>
<li>Reset the thermostat settings</li>
<li>Update the software</li>
</ul>
<p>If you&rsquo;ve tried the above DIY fixes and are still experiencing issues, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">get in touch with a Gas Safe registered engineer</a>. During a callout, they'll check your whole system and get to the bottom of any issues.</p>
<h3>Loss of pressure</h3>
<p>A loss of pressure within your combi boiler can cause your entire system not to heat up as it should and, in some cases, lead to what&rsquo;s known as a boiler lockout. Low water pressure can be caused by a system leak or other issues within the appliance, such as issues with the expansion vessels or pressure relief valve.</p>
<p>If you think low boiler pressure could be the cause of your boiler issue, you can check the pressure gauge on the front of the system. The needle should be sitting in the green zone between 1 and 2 bar. If your pressure is low, you can try <a href="https://www.britishgas.co.uk/the-source/fix-it-yourself/how-to-repressurise-your-boiler.html" rel="follow noopener" target="_blank">repressurising your boiler</a>.&nbsp;</p>
<p>If this doesn&rsquo;t work, you&rsquo;ll need to contact an engineer to come and take a look. They may need to repair or replace faulty components or carry out more complex maintenance on your home&rsquo;s central heating system.</p>
<h3>Strange noises</h3>
<p>Household appliances can make a selection of weird and wonderful <a href="https://www.boxt.co.uk/boilers/guides/9-reasons-why-your-boiler-is-making-a-noise" rel="follow">noises</a> as they serve your home, but sometimes, rumbles and gurgles can shed light on a more significant issue with your combi boiler.</p>
<p>If you hear bubbling and gurgling from your combi boiler, air could be trapped in the system, limescale buildup, a damaged pump, or low water pressure.</p>
<p>Because a number of different things can cause these strange noises, there are several DIY fixes you can try before <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">calling an engineer</a>, including bleeding the radiators, checking the water pressure or adjusting the temperature settings.</p>
<p>Read our full guide on <a href="https://www.boxt.co.uk/boilers/guides/9-reasons-why-your-boiler-is-making-a-noise" rel="follow">why your boiler might be making a noise</a>, or watch our troubleshooting video below for more information.</p>

center

<h3>Frozen condensate pipe</h3>
<p>If you have a modern condensing gas combi boiler, it will have a condensate pipe and flue. Sections of these pipes sit outside your property, leaving any liquids inside at risk of freezing in sub-zero temperatures. Frozen condensate pipes are a common boiler issue in the UK during the winter months.&nbsp;</p>
<p>Symptoms can include gushing sounds from the boiler, frequent lockouts and visible ice on the outside of the pipe itself.</p>
<p>If you suspect your condensate pipe is frozen, you can try to reset the system. Or, if your condensate pipe runs externally, you could try thawing it by pouring hot (not boiling) water onto it. If neither of these fixes works, contact an engineer.&nbsp;</p>
<p>Here, you can read our complete guide on <a href="https://www.boxt.co.uk/boilers/guides/how-to-fix-a-frozen-boiler-condensate-pipe" rel="follow">how to fix a frozen condensate pipe</a>.</p>
<h3>Kettling</h3>
<p><a href="https://www.boxt.co.uk/boilers/guides/boiler-kettling" rel="follow">Kettling</a> is when water begins to boil inside the boiler. Even though this might not sound like a problem, the water inside your boiler (whether it&rsquo;s combi, system or standard) should never actually reach boiling point. If it does begin to kettle, it will generate steam inside the system and, as the name suggests, cause a loud rumbling or whistling noise, just like a kettle.&nbsp;</p>
<p>In terms of symptoms, you might notice a decreased efficiency with your system. This means it may cost more to heat your home, or your boiler won't be heating up as it should. It could also mean a potential fluctuation in boiler pressure.</p>
<p>The causes for kettling can vary, but some leading causes are limescale buildup, debris or sludge in the system, incorrect pump settings or a failure causing overheating.</p>
<p>If you're experiencing kettling in your combi boiler, don&rsquo;t try and fix it yourself. <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact a Gas Safe registered engineer</a> to come and service or repair the system.</p>
<h3>Cold radiators</h3>
<p>Everyone knows that sinking feeling when you think the heating is on, but your radiators aren't warming up as they should. Maybe you can feel cold patches on the bottoms of one or more of your radiators, or perhaps certain areas of your home feel warmer than the others.</p>
<p>If your <a href="https://www.boxt.co.uk/boilers/guides/radiator-cold-at-bottom" rel="follow">radiators are cold</a>, it can mean many things. If you have cold spots towards the bottom of your radiators, then there is more than likely magnetite or sludge in them, which has settled in the bottom, preventing correct heat transfer. This will require a <a href="https://www.boxt.co.uk/boilers/guides/power-flush" rel="follow">system flush</a> to remove the sludge and resolve the issue.</p>
<p>If they are cold at the top, this will more than likely be due to air trapped in them, and they need bleeding.&nbsp;</p>
<p>If air is trapped in your radiators this can be solved by bleeding your radiators. You can learn <a href="https://www.boxt.co.uk/boilers/guides/how-to-bleed-a-radiator" rel="follow">how to bleed a radiator</a> by reading our expert&rsquo;s guide.&nbsp;</p>
<p>If you've bled your radiators and they still aren't functioning as expected, then <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call an engineer</a> to take a closer look.</p>
<h3>Repeated lockouts</h3>
<p>Boiler manufacturers use the term boiler lockout when a boiler has shut down. When a boiler has a fault, the 'lockout' function shuts the system down to prevent further damage.&nbsp;</p>
<p>Depending on what kind of boiler you own, the interface may have a flashing light or an error code.</p>
<p>Combi boiler lockouts are usually because of one of the following reasons:</p>
<ul>
<li>Fan issues</li>
<li>Pump failure</li>
<li>Power cut</li>
<li>An ignition problem</li>
<li>A system blockage</li>
</ul>
<p>To fix a combi boiler lockout, you can try resetting the system and see if anything changes. Beyond this, frequent lockouts are a sign that your system needs to be examined, <a href="https://www.boxt.co.uk/home-cover" rel="follow">serviced</a> or repaired by a qualified boiler engineer.</p>
<h2>Explore your heating options with BOXT</h2>
<p>While an issue with your boiler might seem like the end of the world, many can be solved by a Gas Safe registered engineer in a single visit.</p>
<p>Here at BOXT, we strive to provide prompt, high-quality services nationwide. If you ever think your boiler needs fixing, contact our team, and we can arrange a callout.</p>
<p>If your combi boiler is over 15 years old, it might be time for a more energy-efficient replacement. Tell us a few details about your home and its heating needs, and we&rsquo;ll recommend top-performing <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> models at fair, fixed prices.</p>

Learn

Common combi boiler problems and how to fix them

Looking to learn more about your boiler? Take a look at our comprehensive guide on how to reset a boiler. Featuring Baxi, Vaillant, Ideal and Worcester Bosch.

<p>The wonderful world of <a href="https://www.boxt.co.uk/boilers" rel="follow">boilers</a>. These domestic workhorses are the household's unsung heroes, especially during the winter months.</p>
<p>When it comes to your heating system, it pays to know your way around it. This way, if any issues arise, you'll have a better idea of how to tackle them and get your home running as it should once again.</p>
<p>A handy tip in boiler maintenance is knowing how to reset your boiler. Below, we'll go through some of the most common models on the market today and how to reset them when the need presents itself.</p>
<h2>Safety precautions</h2>
<p>Resetting a boiler using the controls is not classed as working on the boiler, so homeowners can safely do this. Any more in-depth work must be performed by a qualified, Gas Safe registered engineer. If a problem persists after resetting the boiler, you should <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe engineer</a>, as there might be an underlying issue that resetting alone won&rsquo;t resolve.</p>
<h2>Signs your boiler might need to be reset</h2>
<p>It&rsquo;s important only to reset your boiler when something is actually wrong, which means it&rsquo;s important to be able to recognise the telltale signs of an internal issue somewhere in the system.</p>
<p>Here are some of the most common symptoms to look out for as a signal to reset your boiler.</p>
<ul>
<li><strong>No heating or hot water</strong>: If your boiler isn't performing as it should, it may benefit from a reset.</li>
<li><strong>Error codes</strong>: Fault or error codes are a great way to identify an issue with your boiler. If you check your boiler's manufacturer's notes, it may suggest resetting the boiler to tackle an error code.</li>
<li><strong>Thermostat malfunction</strong>: The boiler thermostat can sometimes stop working in sync with the system. Resetting the boiler can help get things working as they should.</li>
<li><strong>A power cut</strong>: If your home has suffered a power outage, there's a good chance your boiler will need to be reset, as it could have forced a boiler lockout.</li>
</ul>
<p>Whilst these symptoms can often be remedied with a simple reset, it is crucial that you do not carry out any work on your boiler. <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Get in touch with a Gas Safe registered engineer</a> if any issues with your boiler persist so they can investigate further and resolve any issues you still have.&nbsp;</p>
<h2>How to reset a Baxi boiler</h2>
<p>Baxi boilers tend to be able to be reset in three different ways, depending on their design. These are as follows.<br>Resetting a Baxi boiler with a reset button<br>In this scenario, press the reset button and hold until you can hear the boiler resetting.</p>
<h3>Resetting a Baxi boiler with a thermostat control knob</h3>
<p>Turn the thermostat control knob anticlockwise. Hold until the red lockout light turns off, and then turn back to your desired setting.</p>
<h3>Resetting a Baxi boiler with an ON/OFF/SELECTOR switch</h3>
<p>Here, you must open the pull down panel to show the full control panel.</p>
<p>To reset the boiler, you need to turn the selector switch to the R (Reset) position, hold for at least 5 seconds, and release.</p>
<p>Visit the manufacturer&rsquo;s website for more information on <a href="https://www.baxi.co.uk/faqs/how-to-reset-a-baxi-boiler" rel="follow noopener" target="_blank">resetting Baxi boilers</a>.</p>
<h3>How to reset an Ideal boiler</h3>
<p>With Ideal boilers, most of the reset buttons can be found beneath the display screen. For boilers with a digital display, you will likely find the reset option in the "settings" section of the menu. You can find exactly where the reset button is if you take a look at the manufacturers' notes.</p>
<p>Below are some of the top models from Ideal's range and how to reset them.</p>
<h3>Resetting Ideal Espirit Eco 2 boilers</h3>
<p>To reset this boiler, press the select and arrow up button for 2 seconds at the same time.</p>
<h3>Resetting Ideal Logic boilers</h3>
<p>Press the reset button on the front of the boiler. It will then repeat its ignition sequence.</p>
<h3>Resetting Ideal Logic + boilers</h3>
<p>The reset button is below the digital display. Press it once.</p>
<h3>Resetting Ideal Vogue Max boilers</h3>
<p>Press the reset button underneath the digital display.</p>
<p>Read our blog on <a href="https://www.boxt.co.uk/boilers/guides/how-to-restart-or-reset-ideal-boilers" rel="follow">resetting your Ideal boiler</a> or visit <a href="https://idealheating.com/user-guides" rel="follow noopener" target="_blank">Ideal&rsquo;s website</a> for more information.</p>
<h2>How to reset a Navien boiler</h2>
<p>With <a href="https://www.boxt.co.uk/boilers/navien-boilers" rel="follow">Navien boilers</a>, the reset button is often located on the front panel, near the control display screen. Below are some of the top models in their range and specifics on how to reset them.</p>
<h3>Resetting Navien NCB300 boilers</h3>
<p>Resetting this boiler is as simple as pressing the power button. Failing this, consult the manufacturer's notes.</p>
<h3>Resetting Navien LCB700, NCB700, &amp; NCB500 boilers</h3>
<p>Press the back button to reset the LCB700, NCB500 and NCB700 boilers. If the boiler does not restart, look at the manufacturer's notes.</p>
<h3>Resetting Navien NCB-24LDWE boilers</h3>
<p>To reset this model, press the reset button on the boiler's front panel.</p>
<p>We have a dedicated blog for <a href="https://www.boxt.co.uk/boilers/guides/navien-boiler-reset" rel="follow">resetting Navien boilers</a>, so be sure to read on for more information on the topic. To learn more about resetting other Navien models, you can check <a href="https://navien.co.uk/support/manuals-and-brochures/" rel="follow noopener" target="_blank">Navien&rsquo;s boiler page</a> directly.</p>
<h2>How to reset a Vaillant boiler</h2>
<p>The boiler reset button on most Vaillant models is located on the boiler's display and will show an icon of a flame with a line crossed through it.</p>
<p>To reset a Vaillant boiler, you need to hold this button down for three seconds. You will know it has worked as the display screen will change, and you will hear the boiler reset.</p>
<p>While this is the case for most Vaillant boilers, it always makes sense to check your user manual or the <a href="https://www.vaillant.co.uk/advice/understanding-heating-technology/boilers/how-to-reset-a-boiler/" rel="follow noopener" target="_blank">Vaillant website</a> if you are unsure.</p>
<h2>How to reset a Worcester Bosch boiler</h2>
<p>If your Worcester Bosch boiler has stopped working properly or the blue light on the front of the system is flashing, it may be worth trying a reset.</p>
<p>There are some subtle variations in methods from model to model, so we'll outline the steps for the most common Worcester Bosch boilers below.</p>
<h3>Resetting Worcester 4000 boilers</h3>
<p>On the digital display, scroll using the up and down keys until you see the word "reset". Press that, and the boiler should restart at its current temperature.</p>
<h3>Resetting Worcester Greenstar Si, i &amp; CDi Compact Boilers</h3>
<p>Press the reset button. A tick should briefly appear.</p>
<h3>Resetting Worcester Greenstar CDi Boilers</h3>
<p>Hold the reset button for three seconds.</p>
<p>The blue light flashing will stop at the reset button and fault indicator. If the reset is successful, the boiler will start again. If not, an alert code will display, in which case you should get in touch with a qualified engineer.</p>
<h3>Resetting Worcester Greenstar Ri boilers</h3>
<p>If there is a fault, the blue mains light will flash.</p>
<p>To reset, turn the central heating temperature knob clockwise until it reaches the &ldquo;RESET&rdquo; position. Hold the button down for 5 seconds and then return to the original temperature setting.</p>
<p>The boiler should reset.</p>
<p>If the boiler you&rsquo;re looking for isn&rsquo;t on this page, take a look at <a href="https://www.worcester-bosch.co.uk/support/manuals-and-brochures" rel="follow noopener" target="_blank">Worcester Bosch&rsquo;s manual and brochures</a> page for further information.</p>
<h2>Replace your boiler with an A-rated model from BOXT</h2>
<p>If you&rsquo;re having to reset your boiler regularly, you could be due a <a href="https://www.boxt.co.uk/boilers/boiler-replacement" rel="follow">new boiler</a>. Find the perfect upgrade for your home with BOXT. We supply a range of A-rated boilers that deliver on efficiency, usability, and price.</p>
<p>Rather not pay it all at once? We understand. Take a look at our <a href="https://www.boxt.co.uk/boilers/subscription" rel="follow">boiler subscription</a> offering, where you can heat your home with a brand-new system for as little as &pound;30 a month.</p>
<p>If you aren&rsquo;t sure where to start, <a href="https://www.boxt.co.uk/contact-us" rel="follow">get in touch</a> with one of our team to find out how we can help your home reach optimal performance.</p>

Find a new, A-rated boiler for your home in just 90 seconds with us

How to reset a boiler

Explore how to prepare your home for a boiler replacement in this BOXT guide, including four key things you should do before the engineer arrives.

<p>Installing a <a href="https://www.boxt.co.uk/boilers/boiler-replacement" rel="follow">new boiler</a> in your home can sometimes be a long and disruptive process, especially if it&rsquo;s being installed in a different location than your old boiler.</p>
<p>But, to minimise installation times and maximise efficiency, there are things you can do to help the Gas Safe registered engineer who'll be carrying out the work.</p>
<p>In this guide, we explore four tips to help you prepare for your <a href="https://www.boxt.co.uk/boilers/boiler-replacement" rel="follow">boiler replacement</a> and ensure the installation process is as smooth and straightforward as possible. But first, let's explore why preparing your home for its new heating system is a good idea.</p>
<h2>How to prepare for boiler installation</h2>
<p>Before the Gas Safe engineer fits your new boiler, complete the following tasks to ensure the <a href="https://www.boxt.co.uk/boilers/boiler-installation" rel="follow">boiler installation</a> process goes as smoothly as possible.</p>
<h3>1. Clear the area and a pathway to your boiler</h3>
<p>Whether you&rsquo;re having your new boiler installed in the same place as your old one or opting to have it moved to a new location, you need to make sure the area around your boiler is clear. You should also ensure the existing system, radiators, water stop tap, and gas meter are accessible and that the new boiler location is clean, too, if it&rsquo;s being relocated. Additionally, if the new boiler is to be installed in the loft, the floor in the loft would need to be boarded and also has a fixed light and a fixed loft ladder.</p>
<p>Once you've cleaned around where the boiler will be installed, you must ensure a pathway from there to the front or back door. The engineer will likely be nipping in and out to their van to fetch various tools, not to mention carrying the new boiler into your home. Guaranteeing ease of access reduces installation time and makes the process much easier and safer.</p>
<h3>2. Identify any areas of concern</h3>
<p>Before installing the boiler, you should identify additional concerns in your heating system. This could include rusty pipework, problematic radiators or inconsistent pressure levels. Basically, anything you'd like the engineer to look at, make them aware of it before they get to work installing your <a href="https://www.boxt.co.uk/boilers/boiler-replacement" rel="follow">replacement boiler</a>.</p>
<p>Flagging any issues will mean the engineer can advise or could even fix them while they install your boiler or organise a time to come back and resolve the issue.</p>

Find out more about common boiler problems and how to identify them.

Common boiler problems

<h3>3. Keep little ones out of the way</h3>
<p>As well as clearing space for your boiler to be installed, you need to make sure children and pets are kept out of the way. This is more of a health and safety concern as opposed to something that will increase productivity, but it may help the engineer concentrate on their work.</p>
<p>Pets, in particular, can be a hazard, so it's important you keep them away from the work area and ensure the engineer has enough space to work.</p>
<h3>4. Identify your home&rsquo;s fuse box or consumer unit</h3>
<p>Whether you&rsquo;re getting a system, standard or combi boiler installed, every boiler needs to be connected to your home&rsquo;s electricity supply. Contrary to popular belief, even gas and oil boilers rely on electricity to ignite, so you&rsquo;ll need to locate the boiler's electrical isolation point (fused spur) and potentially your property&rsquo;s fuse box before your engineer arrives.&nbsp;</p>
<p>If possible, make it easy for your engineer to access the boiler&rsquo;s fused spur or fuse box by clearing a safe pathway to the switch or fuse box then show them the specific switch that controls your boiler. Making sure the engineer only flips the necessary fuse will prevent other areas and appliances in your home from ending up without power.</p>

Learn how and why gas boilers need electricity to heat our homes in our expert's guide.

Do gas boilers use electricity?

<h2>What is the new boiler installation process?</h2>
<p>Once you've cleared the area where the boiler will be installed, found the fuse and any areas for concern, and got your pets or kids out of harm's way, the installation can begin. But what happens when the engineer arrives at your home with a new boiler? Here's what happens in seven simple steps:</p>
<p><strong>1. The boiler and/or system electricity supply needs switching off</strong>: Isolating the electrics before the installation ensures safe working, and the electricity supply may require turning off at different times during the installation to install new controls or even a new fused spur.</p>
<p><strong>2. The gas will need isolating and testing for leaks before the installation</strong>: Testing for gas leaks before installation is important to identify any unsafe situations with the supply and, where practical, resolve and/or repair.</p>
<p><strong>3. The system is drained and the old boiler removed</strong>: The existing system will be firstly drained of all water, and the old boiler will then be removed. Removing smaller appliances, like combi boilers, can be relatively straightforward, but larger heating systems, e.g. those with water storage tanks/cylinders, will take longer.</p>
<p><strong>4. The area is checked and prepared</strong>: During this process, the engineer will assess the boiler's flue system to ensure it complies with the manufacturer's instructions and building regulations or what needs to be done to ensure the new flue complies.</p>
<p><strong>5. The heating system is flushed and cleaned</strong>: Following British standards,&nbsp;engineers should&nbsp;<a href="https://www.boxt.co.uk/boilers/guides/power-flush" rel="follow">flush</a> your central heating system each time a new boiler is installed.</p>
<p><strong>6. The pipework is upgraded</strong>: If you want your boiler to be moved or the pipework looks worse for wear, the engineer will upgrade some or all of the pipes, including the gas pipework, where necessary.</p>
<p><strong>7. The new boiler is installed, and accessories are fitted</strong>: Straightforward installations can be completed within a day, but more complicated work can be significantly longer. Once the boiler is installed, the engineer can work on fitting accessories, like <a href="https://www.boxt.co.uk/boilers/guides/magnetic-boiler-filters" rel="follow">system filters</a>, condensate pumps and additional required flue lengths.</p>
<p><strong>8. Checks are carried out</strong>: The boiler will be tested to ensure it works properly and should be commissioned in accordance with the manufacturer's instructions.</p>
<p><strong>9. The boiler is registered</strong>: Once installed, the engineer will register your new boiler with Gas Safe, the relevant local authorities, and the boiler manufacturer to validate the appliance's warranty. At BOXT, we do this for you!</p>
<p>Check out our blog for a more detailed look at <a href="https://www.boxt.co.uk/boilers/guides/what-happens-when-a-new-boiler-is-fitted" rel="follow">what happens when a new boiler is fitted</a>, including whether your water and gas supply will need to be turned off.</p>
<h3>What is the average installation time for a new boiler?</h3>
<p>The time it takes to install a boiler depends on the size and scale of the installation, but it's typically between one and two days. Explore the factors that can prolong the process in our '<a href="https://www.boxt.co.uk/boilers/guides/how-long-does-it-take-to-fit-a-new-boiler" rel="follow">How long does it take to fit a new boiler?</a>' guide.</p>
<h3>Is it better to repair your current boiler or replace it?</h3>
<p>Deciding whether to replace or repair your boiler is a tricky decision; on the one hand, the short-term cost of <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">repairing your boiler</a> may be cheaper than a new model; on the other hand, a new appliance offers long-term peace of mind.</p>
<p>To help you make an informed decision, we explore the pros and cons of each side in our '<a href="https://www.boxt.co.uk/boilers/guides/boiler-repair" rel="follow">New boiler vs boiler repair</a>' blog.</p>
<h2><strong>Get your next boiler from BOXT</strong></h2>
<p>Still on the search for your next appliance? Take a look at <a href="https://www.boxt.co.uk/boilers/guides/how-to-choose-your-perfect-boiler">how to choose your perfect boiler</a> for tips on making the right purchase.</p>
<p>Ready to get your new boiler? With BOXT, you could have a new appliance installed as early as tomorrow. Use our <a href="https://www.boxt.co.uk/find-a-boiler/">Find a Boiler</a> tool to get started and look forward to a more affordable, more comfortable home.</p>

Get fixed-price quotes for A-rated replacement boilers from BOXT

How to prepare your home for a boiler replacement

Find full lists of Ideal boiler error and fault codes alongside possible causes and solutions. Keep your Ideal boiler running smoothly with help from BOXT.

<p>Noticing that there&rsquo;s a fault with your Ideal <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> is less than ideal, but getting it sorted doesn&rsquo;t have to be as much of a hassle as you&rsquo;d expect.</p>
<p>It&rsquo;s important to note that once you&rsquo;ve discovered an issue with your system, a Gas Safe registered engineer needs to be called to diagnose and rectify the problem fully.</p>
<p>To make the process of diagnosing any problems as painless as possible, Ideal pre-programs its boilers with fault and error codes. These codes are displayed on the user interface to alert you and your engineer to anything that needs attention within the system.</p>
<p>Here, we&rsquo;ll cover all of the most common Ideal boiler fault codes, discussing their meaning and advising on any next steps that you or a Gas Safe registered engineer can take to get things back to working as they should.</p>
<h2>Ideal boiler fault &amp; error codes by boiler model</h2>
<ul>
<li><a href="#h_283069789193621705408930675" rel="follow">Ideal boiler F fault codes</a></li>
<li><a href="#h_373458347195981705408940506" rel="follow">Ideal boiler L fault codes</a></li>
<li><a href="#h_651947860197021705408948577" rel="follow">Ideal boiler C fault codes</a></li>
<li><a href="#h_541516278198321705408957447" rel="follow">Additional Ideal boiler fault codes</a></li>
</ul>
<h2 id="h_283069789193621705408930675">Ideal boiler F fault codes</h2>
<table border="1" style="border-collapse: collapse; width: 100.054%; height: 293.907px;"><colgroup><col style="width: 16.4882%;"><col style="width: 40.1695%;"><col style="width: 43.3423%;"></colgroup>
<tbody>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;"><strong>Error code</strong></td>
<td style="height: 19.5938px;"><strong>Problem</strong></td>
<td style="height: 19.5938px;"><strong>Solution</strong></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F</td>
<td style="height: 19.5938px;">Boiler operating in frost mode.</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">FD</td>
<td style="height: 39.1875px;">No water flow</td>
<td style="height: 39.1875px;">Repressurise the boiler. If this doesn&rsquo;t resolve the issue, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call an engineer</a>.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">FU</td>
<td style="height: 19.5938px;">Flow/return differential &ndash; 50&deg;C</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F1</td>
<td style="height: 19.5938px;">Low boiler pressure</td>
<td style="height: 19.5938px;">Top up the <a href="https://www.boxt.co.uk/boilers/guides/boiler-pressure" rel="follow">water pressure</a>.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">F2/FL</td>
<td style="height: 39.1875px;">Flame loss</td>
<td style="height: 39.1875px;">Reset the boiler. If this doesn&rsquo;t resolve the issue, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call a Gas Safe engineer</a>.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F3</td>
<td style="height: 19.5938px;">Fan fault</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F4</td>
<td style="height: 19.5938px;">Thermistor fault</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F5</td>
<td style="height: 19.5938px;">Return thermistor fault</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F6</td>
<td style="height: 19.5938px;">Outside sensor fault</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F7</td>
<td style="height: 19.5938px;">Low mains voltage</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F8</td>
<td style="height: 19.5938px;">Printed circuit board (PCB) fault</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">F9</td>
<td style="height: 19.5938px;">Unconfigured PCB.</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
</tbody>
</table>
<h2 id="h_373458347195981705408940506">Ideal boiler L fault codes</h2>
<table border="1" style="border-collapse: collapse; width: 100.054%; height: 431.063px;"><colgroup><col style="width: 16.8094%;"><col style="width: 40.0532%;"><col style="width: 43.0303%;"></colgroup>
<tbody>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;"><strong>Error code</strong></td>
<td style="height: 19.5938px;"><strong>Problem</strong></td>
<td style="height: 19.5938px;"><strong>Solution</strong></td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">L1</td>
<td style="height: 39.1875px;">Low water flow</td>
<td style="height: 39.1875px;">Reset the boiler. If this doesn&rsquo;t resolve the issue, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call an engineer</a>.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">L2</td>
<td style="height: 39.1875px;">Ignition lockout</td>
<td style="height: 39.1875px;">Reset the boiler. If you hear a <a href="https://www.boxt.co.uk/boilers/guides/9-reasons-why-your-boiler-is-making-a-noise" rel="follow">rumbling noise</a>, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call an engineer</a>.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">L3</td>
<td style="height: 19.5938px;">No flow thermistor fault</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">L9/H9/HA/LA</td>
<td style="height: 39.1875px;">Overheating</td>
<td style="height: 39.1875px;">Check pressure readings and <a href="https://www.boxt.co.uk/boilers/guides/how-to-bleed-a-radiator" rel="follow">bleed your radiators</a>. If no change, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call an engineer</a>.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">LF</td>
<td style="height: 39.1875px;">Ignition fault</td>
<td style="height: 39.1875px;">Reset your boiler. If your boiler is rumbling, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a qualified engineer</a>.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">L4</td>
<td style="height: 39.1875px;">Flow thermistor fault</td>
<td style="height: 39.1875px;">Restart the boiler. If the issue continues, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact an engineer</a>.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">L5</td>
<td style="height: 39.1875px;">Boiler return pipe issue</td>
<td style="height: 39.1875px;">Turn off the boiler&rsquo;s power at the fuse spur, then turn it back on. If the issue persists, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">call an engineer</a>.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">L6</td>
<td style="height: 39.1875px;">Flame detection fault</td>
<td style="height: 39.1875px;">Reset your boiler. If the problem persists, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact an engineer</a>.</td>
</tr>
<tr style="height: 58.7812px;">
<td style="height: 58.7812px;">LC</td>
<td style="height: 58.7812px;">5 boiler resets in 15 minutes.</td>
<td style="height: 58.7812px;">Turn the electrical supply to the boiler off and on. If the boiler fails to operate, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe registered engineer</a>.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">L9</td>
<td style="height: 19.5938px;">Unconfigured PCB</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">L-F</td>
<td style="height: 19.5938px;">Boiler fails to ignite</td>
<td style="height: 19.5938px;">Try resetting the boiler. If nothing changes, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact an engineer</a>.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">L-A</td>
<td style="height: 19.5938px;">Boiler overheated</td>
<td style="height: 19.5938px;">Check that there is <a href="https://www.boxt.co.uk/boilers/guides/boiler-pressure" rel="follow">sufficient water pressure</a> in the central heating system and that all radiators have been bled. Then, reset the boiler. If the issue persists, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact an engineer</a>.</td>
</tr>
</tbody>
</table>
<h2 id="h_651947860197021705408948577">Ideal boiler C fault codes</h2>
<table border="1" style="border-collapse: collapse; width: 100.054%; height: 117.563px;"><colgroup><col style="width: 17.1306%;"><col style="width: 40.1599%;"><col style="width: 42.6025%;"></colgroup>
<tbody>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;"><strong>Error code</strong></td>
<td style="height: 19.5938px;"><strong>Problem</strong></td>
<td style="height: 19.5938px;"><strong>Solution</strong></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">C2</td>
<td style="height: 19.5938px;">Boiler chip card fault.</td>
<td style="height: 19.5938px;">Reset your boiler. If the issue persists, <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact an engineer</a>.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">C0</td>
<td style="height: 19.5938px;">Central heating signal issue.</td>
<td style="height: 19.5938px;"><a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Contact an engineer.</a></td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">C</td>
<td style="height: 19.5938px;">The boiler is operating in central heating mode. Or the boiler has a call for central heating, and the appliance has reached the desired set temperature.</td>
<td style="height: 19.5938px;">No solution needed. This is a setting, not a problem.</td>
</tr>
</tbody>
</table>
<h2 id="h_541516278198321705408957447">Additional Ideal boiler fault codes</h2>
<table border="1" style="border-collapse: collapse; width: 100.054%; height: 156.75px;"><colgroup><col style="width: 17.0236%;"><col style="width: 40.3739%;"><col style="width: 42.4955%;"></colgroup>
<tbody>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;"><strong>Error code</strong></td>
<td style="height: 19.5938px;"><strong>Problem</strong></td>
<td style="height: 19.5938px;"><strong>Solution</strong></td>
</tr>
<tr style="height: 58.7812px;">
<td style="height: 58.7812px;">D</td>
<td style="height: 58.7812px;">The boiler is operating in hot water mode, or the boiler has a call for hot water and the appliance has reached the desired set temperature.</td>
<td style="height: 58.7812px;">No solution needed; this is a setting.</td>
</tr>
<tr style="height: 39.1875px;">
<td style="height: 39.1875px;">0</td>
<td style="height: 39.1875px;">The boiler is in standby mode awaiting hot water requests or a central heating call.</td>
<td style="height: 39.1875px;">Choose your settings.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">H-3</td>
<td style="height: 19.5938px;">Domestic hot water thermistor error.</td>
<td style="height: 19.5938px;">Reset the system.</td>
</tr>
<tr style="height: 19.5938px;">
<td style="height: 19.5938px;">No display</td>
<td style="height: 19.5938px;">No heating or hot water.</td>
<td style="height: 19.5938px;">This is a PCB error. <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Call an engineer</a>.</td>
</tr>
</tbody>
</table>
<h2>Protect your home&rsquo;s central heating with BOXT</h2>
<p>Luckily, the majority of Ideal <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> problems are relatively quick and easy for qualified engineers to fix, provided they&rsquo;re identified promptly. If you suspect that any of the issues mentioned above are to blame for your boiler&rsquo;s malfunctioning, and the recommended fix isn&rsquo;t as simple as pressing the reset button, always contact a Gas Safe registered engineer who&rsquo;ll be able to come and assist you.</p>
<p>Sometimes, it&rsquo;s better to be safe than sorry. We all know that household issues arise when you&rsquo;re least prepared for them, so it helps to have a good idea of how your boiler is performing.&nbsp;</p>
<p>If you&rsquo;re unsure about the current performance of your boiler, why not book a <a href="https://www.boxt.co.uk/boilers/boiler-servicing" rel="follow">boiler service</a>? With the help of our engineers, you&rsquo;ll be sound in the knowledge that your boiler is doing the most it can possibly do for your home.</p>

Ideal boiler fault & error codes

Find full lists of Baxi boiler error and fault codes with possible causes and fixes. Resolve issues with combi, system and standard boilers.

Get in touch with our Gas Safe registered engineers today

Baxi Boiler fault & error codes

Find full lists of Vaillant boiler error and fault codes with possible causes and fixes. Resolve issues with combi, system and standard boilers.

Vaillant boiler fault & error codes

BOXT engineer arriving at the front door with his tool box

Facing Navien boiler problems? Explore these common issues, their causes, and what to do when you encounter them.

<p>Even though it&rsquo;s a relative newcomer to the UK <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> market, <a href="https://www.boxt.co.uk/boilers/navien-boilers" rel="follow">Navien</a> is one of the most trusted manufacturers there is. Across the Far East, consumers see Navien as the go-to brand for domestic home heating solutions, celebrating their industry-leading technologies, incredible energy efficiency and user-friendly features.</p>
<p>But no technology is perfect, and even the most reliable models can encounter issues from time to time. If you happen to experience a problem with your Navien boiler, getting it fixed promptly will be a top priority for everyone living in your property. Luckily, most issues can be rectified by a qualified professional pretty easily.</p>
<p>In this guide, we&rsquo;ll walk you through some of the common problems you may encounter with a Navien boiler. We&rsquo;ve split this into issues that you should be able to remedy yourself and urgent problems that should only be attempted by a Gas Safe registered engineer (such as the team at BOXT).&nbsp;</p>
<h2>Common Navien boiler problems and fixes</h2>
<p>When there's a problem with your boiler, you'll usually notice an error code or an issue with your pressure gauge being too high or too low.&nbsp;<br>Here are some of the most common Navien boiler problems and the steps you can take to fix them.</p>
<p><strong>Please note: </strong>While these fixes can be performed yourself; if you don&rsquo;t feel confident, don&rsquo;t hesitate to enlist the help of a professional.&nbsp;</p>
<h3>Ignition failure</h3>
<p>One of the most common error codes for Navien boilers is E003, which indicates there's an ignition fault.</p>
<p>If you encounter this error code, try restarting your boiler and checking the gas supply. If you've already tried those things and your boiler still fails to ignite, you should contact a Gas Safe registered engineer to determine the exact problem.</p>
<p>They'll likely need to access and inspect the boiler's controls to find the cause, whether it's debris or faulty parts.</p>
<h3>Low pressure</h3>
<p>If your pressure gauge is showing <a href="https://www.boxt.co.uk/boilers/guides/why-does-my-boiler-pressure-keep-dropping" rel="follow">little to no pressure in your boiler</a>, it likely means the water pressure in your boiler is too low for the system to work efficiently. You might also see the error code E302.</p>
<p>Low pressure can be down to numerous things, including a potential fault with the pressure relief valve or a leak within the boiler or on the system pipework.</p>
<p>If you aren't confident in attempting to raise your boiler's pressure yourself, please contact one of our expert Gas Safe registered engineers to help you.</p>
<h3>High pressure</h3>
<p>If your <a href="https://www.boxt.co.uk/boilers/guides/is-your-boiler-pressure-too-high-heres-what-to-do" rel="follow">boiler's pressure gauge is too high</a>, contact a Gas Safe registered engineer who will be able to give you expert advice.<br>For more information, see our <a href="https://www.boxt.co.uk/boilers/guides/boiler-pressure" rel="follow">complete guide to boiler pressure</a>.</p>
<p><img src="https://cdn.buttercms.com/kLpNELX3Qfy2A79LZQWJ" alt="BoilerInstall-carousel08.webp"></p>
<h2>Urgent Navien boiler problems and fixes</h2>
<p>Below are some of the most common urgent boiler problems and their potential causes. If you encounter one of these issues with your boiler, it is essential to seek an emergency boiler call out from a Gas Safe registered engineer.&nbsp;</p>
<p><strong>Important: </strong>Do <strong>NOT</strong> attempt these fixes yourself.&nbsp;</p>
<h3>Overheating heat exchanger</h3>
<p>An overheating heat exchanger (error code E016 or E046) occurs when the component responsible for transferring heat from the burner to the water becomes excessively hot.</p>
<p>This can be caused by issues such as a lack of water flow or blocked pipes. An overheating heat exchanger can lead to serious safety hazards, including potential damage to the boiler and a risk of carbon monoxide leakage, which is also <a href="https://www.boxt.co.uk/boilers/guides/carbon-monoxide-testing" rel="follow">why it&rsquo;s important to have a working carbon monoxide alarm</a>.</p>
<p>If you suspect this problem, it is crucial to <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe registered engineer</a> to diagnose and address the issue, ensuring both your safety and the efficiency of your boiler.</p>
<h3>Flue issue</h3>
<p>The <a href="https://www.boxt.co.uk/boilers/guides/what-is-a-boiler-flue" rel="follow">boiler flue</a> is a component that connects to your Navien boiler and safely transports the combustion gases to outside&nbsp;<br>Factors like corrosion or obstructions in the flue/exhaust pipe can cause issues, potentially leading to harmful carbon monoxide leaks within your home.</p>
<p>If you encounter any flue related problems or suspect a malfunction, or blocked condensate, it's critical to <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">contact a Gas Safe registered engineer</a> without delay.</p>
<h3>Temperature sensor issue</h3>
<p>The temperature sensors (thermistors) in your Navien boiler are responsible for monitoring and regulating the water's temperature within the appliance.</p>
<p>Issues can include general wear and tear, electrical problems, or sensor misplacement, causing the sensor to give inaccurate readings.</p>
<p>You shouldn't try to fix any underlying issue yourself. <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">Call a Gas Safe registered engineer</a>, who will replace the sensor or find the cause of the inaccurate readings for you.</p>

<h2>Choose BOXT Home Cover</h2>
<p>We know how stressful it can be when your boiler stops working. That's why, at BOXT, we offer <a href="https://www.boxt.co.uk/home-cover" rel="follow">home cover plans</a> with no call-out or excess charges as standard.</p>
<p>Our Gas Safe registered engineers are experienced in installing and maintaining <a href="https://www.boxt.co.uk/boilers/navien-boilers" rel="follow">Navien boilers</a> too, so you, and your heating, will be in safe hands.</p>
<p>For more boiler advice, whether that&rsquo;s information on <a href="https://www.boxt.co.uk/boilers/guides/what-happens-when-a-new-boiler-is-fitted" rel="follow">what happens when a new boiler is fitted</a>, <a href="https://www.boxt.co.uk/boilers/guides/clearing-an-airlock-from-your-central-heating-system" rel="follow">how to clear an airlock</a>, and <a href="https://www.boxt.co.uk/boilers/guides/full-boiler-protection-plans" rel="follow">everything you need to know about full boiler protection plans</a>, check out our <a href="https://www.boxt.co.uk/guides?category=boilers" rel="follow">dedicated boiler guides</a>.</p>
<p>If you're just after some guidance, you can message us on our&nbsp;<a href="https://www.boxt.co.uk/" rel="follow">Live Chat</a> where you get the best advice from our heating specialists.</p>

How to troubleshoot Navien boiler problems

Explore when and how to reset different models of Navien boiler, including the NCB300 and LCB700, and when you should call a Gas Safe registered technician.

<p>Whether you've had your <a href="https://www.boxt.co.uk/boilers/navien-boilers" rel="follow">Navien boiler</a> for a few years or weeks, you will likely need to reset it at some point in its lifespan.</p>
<p>To ensure the efficiency and proper maintenance of your Navien boiler, you must understand what to do when an error message appears and when to press the reset button.</p>
<p>This guide explains everything you need to know about resetting your Navien <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> and ensuring you always have heating and hot water.</p>
<h2>Where is the reset button on a Navien boiler?</h2>
<p>Typically, the reset button on a Navien boiler will be on its front panel, near the control display.&nbsp;</p>
<p>The reset button's precise position on your boiler unit will vary based on the Navien model you own, so it's a good idea to check the instruction manual for the exact location.</p>
<h2>When to reset a Navien boiler</h2>
<p>Occasionally, your boiler may experience faults that require you to press the reset button. If there's a problem with your boiler, like a faulty heat exchanger or water heater, it can shut down completely, known as a 'lockout'.</p>
<p>A boiler will perform a lockout to preserve your safety and avoid a more severe fault occurring. When this happens, you should perform a system reset. Additionally, you may have to reset your boiler if there's a problem with the power supply or a power cut.</p>
<p>You should be aware that resetting your Navien boiler may not fix the issue, and you may need to contact technical support or a Gas Safe registered engineer to investigate the problem further. Where this is the case, the control panel or screen may show an error message or code you can look up in your Navien boiler's instructions.</p>
<p>As with all machines, a mechanical or electrical fault can occur at any time, so it's essential you&nbsp;<a href="https://www.boxt.co.uk/home-cover" rel="follow">get your boiler serviced</a> regularly.</p>

Choose BOXT Home Cover to protect your boiler

<h2>Can you reset a Navien boiler yourself?</h2>
<p><a href="https://www.boxt.co.uk/boilers/guides/boiler-not-firing-up" rel="follow">Resetting your boiler</a> is a straightforward process, so if you feel confident doing it, you can save time and money by doing it yourself. Before you do, read your boiler's manual. You must also wait before pressing the reset button again, as pressing it multiple times in quick succession could cause further problems.</p>
<h2>How to reset a Navien boiler</h2>
<p>Specific reset processes will vary based on the model of the Navien boiler you own. To help you, we've outlined the steps to resetting different Navien models below.</p>
<h3>NCB300</h3>
<p>To reset a Navien NCB300, press the Power button. If this doesn't work, refer to the troubleshooting section of the instruction manual.</p>
<h3>LCB700, NCB700 &amp; NCB500</h3>
<p>Press the Back button to reset an NCB500 boiler. If this doesn't work, contact Navien tech support or consult the manual's troubleshooting section.</p>
<h3>NCB-24LDWE</h3>
<p>Press the Reset button on the system's front panel if an error code appears.</p>
<h2>What happens after you reset your Navien boiler?</h2>
<p>Depending on the extent of the problem, your Navien boiler will either show an error code on its panel display or resolve the issue automatically and get straight back to working as expected.</p>
<p>If your <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> reset has gone to plan, the boiler will fire up as expected, and any error messages will disappear. The reset procedure can take a couple of minutes, so avoid pressing the reset button multiple times - this can cause further complications.</p>
<h2>When to call a professional</h2>
<p>If you press the reset button and the error code persists, contact a trained professional for <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">boiler repairs</a>. You should report any problems quickly so an engineer can fix them before they worsen.</p>
<p>For more <a href="https://www.boxt.co.uk/guides?tag=boiler-maintenance" rel="follow">boiler maintenance</a> advice, check out our blog's dedicated section. Here, you'll find tips and information on everything, from <a href="https://www.boxt.co.uk/boilers/guides/clearing-an-airlock-from-your-central-heating-system" rel="follow">how to clear an airlock</a> to <a href="https://www.boxt.co.uk/boilers/guides/how-to-clean-magnetic-filter-on-boiler" rel="follow">how to clean a magnetic filter</a> and more.</p>

How to reset a Navien boiler

In this guide, we’ll walk you through everything you need to know about your boiler’s condensate pipe, cutting through the jargon so you can feel confident about the inner-workings of your home’s central heating system.

<p>If you&rsquo;re stuck when it comes to knowing your flues from your thermostats and your <a href="https://www.boxt.co.uk/boilers/combi-boilers" rel="follow">combi boilers</a> from your condensing, you&rsquo;re definitely not on your own. Knowing how to identify every pipe, button, and outlet that's attached to your boiler can be tricky.</p>
<p>A repeat offender when it comes to confusing homeowners is condensate pipes. What are they? What do they do? And why are they important?</p>
<p>In this guide, we&rsquo;ll walk you through everything you need to know about your <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a>&rsquo;s condensate pipe, cutting through the jargon so you can feel confident about the inner workings of your home&rsquo;s central heating system.</p>
<h2>Firstly, what is a condensing boiler?</h2>
<p>Before we take a closer look at condensate pipes, we first need to understand what condensing boilers are.&nbsp;</p>
<p><a href="https://www.boxt.co.uk/boilers/guides/what-is-a-condensing-boiler">Condensing boilers</a> are a highly efficient type of home heating system. They are designed to maximise the heating potential of the energy they burn by minimising the amount that&rsquo;s lost when generated as a byproduct. The result? Condensing boilers are able to give you more hot water per penny spent, improving your home&rsquo;s energy efficiency and helping to reduce your carbon footprint in the process.</p>
<p>To do this, condensing boilers capture the products of combustion (fumes) that are generated through the combustion of natural gas, LPG, or oil (depending on the boiler&rsquo;s fuel type) via the heat exchanger. On condensing boilers, these heat exchanges extract more heat from the products of combustion due to their design. So much so that the gases turn, or &lsquo;condensate&rsquo;, back into liquid form. This condensate water is mildly acidic.&nbsp; Condensing appliances can produce up to 3 litres per hour. All of this water has to be collected and removed from the boiler&rsquo;s system, and this is where condensate pipes come in.&nbsp;</p>
<h2>What does a condensate pipe do?</h2>
<p>The condensate pipe is an outlet, usually made from plastic or PVC, that transports acidic wastewater (condensate) from your boiler to drains located outside your home.<br><br>When it&rsquo;s fired up and running, your boiler can generate an impressive 2-3 litres of condensate waste per hour, all of which need to be removed from the system to keep everything operating smoothly and safely.&nbsp;</p>
<p>The condensate pipe is designed to release water once the volume hits a certain threshold and is usually released in around 300ml increments. This is to reduce the risk of the water freezing in the part of the pipe that's outside your home, which could then cause a blockage.</p>
<p>The condensate pipe will usually come out of the back of your boiler, down the external wall, and into the drain. It could also terminate into a waste pipe internally (a sink waste pipe, for example). It's a small, usually-white pipe, so It should be easy to spot amongst the metal pipes.</p>
<h2>What happens if a boiler&rsquo;s condensate becomes blocked?</h2>
<p>Over time, sediment can start to build up in your condensate sump pump and/or pipe. The U bend or syphon-shaped 'trap' part of your condensate pipe, which is responsible for safely collecting and releasing the wastewater, is usually where the sediment will sit. Build-up can come from things like tiny bits of the heat exchanger if it's corroded, which can ultimately end up in your condensate trap.<br><br>If there is enough sediment build-up, condensate wastewater will cease to flow, causing the liquid to back up into the bottom of the heat exchanger. Your boiler will then automatically stop working for safety reasons. &nbsp; <br><br>You shouldn't have to worry too much about this happening if your boiler is regularly serviced. Your heating engineer will clear the condensate trap during your service. Cogged condensate pipe traps are usually only to be expected in appliances that haven't been serviced in a long time.</p>
<p>Telltale signs that your condensate pipe has a blockage include the boiler making a gurgling sound when it&rsquo;s fired up due to wastewater struggling to pass through the pipework and, if the blockage is bad enough, the boiler stopping working altogether.</p>
<p>If you suspect a clogged condensate pipe trap is to blame for your boiler failing, you should contact an engineer rather than trying to fix the problem yourself, as the job requires a <a href="https://www.boxt.co.uk/home-cover">Gas Safe registered expert</a>. Your engineer will clean the trap by removing it and rinsing it out thoroughly before refilling and refitting it.<br><br>If you'd like us to come and take a look, you can <a href="https://www.boxt.co.uk/boilers/boiler-repair">book a boiler repair here</a> by answering a few simple questions about your home and boiler.</p>
<h2>Need a new condensate pipe or condensing boiler?</h2>
<p>Since the legislation was introduced way back in 2005, all new boiler installations must be condensing boilers. This is because condensing boilers are far more efficient than old-style non-condensing boilers, reaching energy efficiencies of above 90%.</p>
<p>At BOXT, we supply a huge range of A-rated condensing boilers from brands such as Ideal, Baxi, Navien and Worcester Bosch with industry-leading home cover <a href="https://www.boxt.co.uk/boilers/boiler-servicing" rel="follow">boiler service</a> plans to keep things running smoothly.</p>

Boiler condensate pipes - What are they and what do they do?

If you can hear strange kettling noises coming from your boiler, take a look at this handy BOXT guide to determine the possible causes and how to fix them. 

<p>Do you have a strange noise coming from your boiler? If so, your boiler might be experiencing what is known as &lsquo;boiler kettling&rsquo;.</p>
<p>We've already covered <a href="https://www.boxt.co.uk/boilers/guides/9-reasons-why-your-boiler-is-making-a-noise" rel="follow">boiler noises</a> in another blog, but we're going to cover kettling in more detail.</p>
<p>So what is boiler kettling, what causes <a href="https://www.boxt.co.uk/boilers" rel="follow">boilers</a> to kettle, and what can you do to fix it? We're going to walk you through everything you need to know.</p>
<h2>What exactly is boiler kettling?</h2>
<p>Before determining the cause of the boiler kettling sounds, it's a good idea to know what boiler kettling actually is. Boiler kettling is a whistling, bubbling or popping noise that comes from your boiler while it's running.</p>
<p>The hot water inside a boiler should not boil. But if something was to cause the water flow inside the system to slow down, there&rsquo;s a chance that the water could well boil. This is when the boiler kettling noise occurs - just like a boiling kettle.</p>
<p>Before coming up with a solution, you'll need to know what's causing this boiler kettling noise.</p>
<h2>Common causes of boiler kettling</h2>
<p>There are three likely causes of boiler kettling: overheating, limescale buildup or a leak. We'll walk you through how to identify the cause of your boiler noise and what can be done to fix the problem.</p>
<h3>Cause 1: Overheating</h3>
<p>If your boiler keeps cutting out and making strange kettling noises, a likely cause is overheating. Often, an overheating boiler is down to a faulty thermostat. If you have a faulty thermostat, take a look at our other guide on <a href="https://www.boxt.co.uk/boilers/guides/thermostat-not-working" rel="follow">why your thermostat may not be working</a> to help find the solution.</p>
<p>Overheating can also be caused by blocked/partially blocked pipework that can happen over time, depending on the age of the system. If you have a blockage, then you potentially would need the system looking at, and a powerflush may be required to remove and clear the blockage.</p>
<p>The kettling noise occurs when a boiler is overheating because the inside of the heating system is getting too hot. The hot water in the boiler system turns into steam, creating the strange kettling noise you can hear coming from your boiler.</p>
<h3>Cause 2: Limescale buildup</h3>
<p>Another reason for boiler kettling could be limescale buildup. No boiler is immune from limescale buildup. But even though it is a natural occurrence, it does need to be dealt with.</p>
<p>If the limescale begins to cause a blockage, the heat and water will only have so much space to move around, which can cause your boiler to make a kettling noise.</p>
<p>Limescale buildup can also cause blockages in the system to the extent that some radiators or appliances aren't working as well as they once did.</p>
<p>Thankfully this isn't a safety issue, but it will need flushing to release any buildup.</p>
<p>If you live in a hard water area, you're much more likely to have limescale buildup in your heating system, as hard water contains more minerals.</p>
<h3>Cause 3: A leak</h3>
<p>A <a href="https://www.boxt.co.uk/boilers/guides/is-a-leaking-boiler-an-emergency" rel="follow">boiler leak</a> can also cause kettling, as the system will try to balance the water flow and pressure. If you think this could be the case for your boiler, you'll need to check for leaks. The leak could be close to the boiler unit or anywhere throughout the pipework.</p>
<p>Your central heating system could be leaking for several reasons, from poorly installed pipework to general corrosion.</p>
<h2>How to fix a kettling boiler</h2>
<p>The right solution for the boiler kettling will depend on what is causing the noise to occur in the first place. If you've read the list of causes above and think you've figured out what might be causing your boiler to make strange kettling sounds, read on to find out what can be done to stop your boiler from kettling.</p>
<h3>Solution 1: How to fix an overheating boiler</h3>
<p>If you think the cause of your boiler kettling might be overheating, check the settings on your thermostat. If you're confident enough, adjust or reset the thermostat to bring your boiler back to a suitable temperature.</p>
<p>The safest option would be to call a heating engineer to find a solution. If your thermostat is broken, you will need a <a href="https://www.boxt.co.uk/boilers/boiler-repair" rel="follow">boiler repair</a> or replacement.</p>
<h3>Solution 2: How to remove limescale buildup in a boiler</h3>
<p>If the boiler kettling noise is a result of limescale buildup, you'll need to get in touch with a heating engineer. They can perform a system flush to clear your system of debris or limescale.</p>
<p>A chemical flush uses high-strength chemicals to corrode the debris, whereas a power flush uses pressurised water to do the same.</p>
<p>If the boiler kettling noise doesn't stop, there will be a different cause elsewhere in the system.</p>
<h3>Solution 3: How to fix a boiler leak</h3>
<p>If you suspect a boiler leak, you'll need a Gas Safe registered engineer to solve the problem. If you attempt to solve the problem yourself, not only could you be putting yourself in danger, but you could also invalidate your boiler warranty or guarantee.</p>
<p>The heating engineer will be able to inspect the entire central heating system and pipework for any potential leaks causing the boiler kettling.</p>

<h2>Is boiler kettling dangerous?</h2>
<p>Boiler kettling doesn't usually indicate immediate danger, but finding a solution as quickly as possible is wise. The high pressure in the boiler could eventually burst internal pipework. However, modern boilers have built-in safeguard features to shut down the boiler before it reaches this point.</p>
<p>Waiting to fix a problem with your <a href="https://www.boxt.co.uk/boilers" rel="follow">boiler</a> could lead to a much bigger issue later down the line, which could be much more costly. If you notice that your boiler is making a kettling noise or not working as well as it once did, it's best to get in touch with a Gas Safe registered engineer for a <a href="https://www.boxt.co.uk/boilers/boiler-servicing" rel="follow">boiler service</a> as soon as possible.</p>

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