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No Hot Water From Boiler, Why and What To Do


Despite reliability being one of the selling points of modern boilers, there is always a risk of things going awry with your boiler. As such, you shouldn’t be surprised to come home on a freezing day and find there is no hot water coming out of your hot taps.

And since the reason for installing your boiler is to provide hot water for central heating and domestic use, you wouldn’t appreciate it absconding this critical duty. But before you panic and call a heating engineer, there is a need to know that the issue isn’t always that serious, and you can resolve some of these problems yourself.

But what might be the reasons why your boiler is firing up but not supplying any hot water? And what are the fixes for some of these problems? Well, if those are your questions on your mind, then you’ve come to the right guide.

In this guide, we will explore some of the reasons why there is no hot water coming out of your boiler and highlight some of the ways you can resolve this issue on your own.

First things to check

Opening your hot taps and finding that the hot water coming out of them isn’t hot can be both unpleasant and inconvenient. But before you set off on your quest to find out whether the issue with your boiler lies with some individual heating system component, there are some general things you need to check first.

  1. Is your boiler working?

It is always advisable to start your search by checking whether the boiler is operating in the first place. And the good thing with modern boilers is that you can quickly tell when they are running finely and when they are faulty.

In most cases, you can tell when your boiler is faulty if it is flashing different display colours along with an error code. By checking the meaning of this error code in your boiler’s manual or online, you can pinpoint the actual problem plaguing your boiler.

And as you’ll find out, some of these fault codes can be resolved with a simple boiler reset. Others, however, are more complex and may need the attention of a professional heating engineer. So if the error code indicates a serious problem, make sure you contact a qualified heating engineer straightaway.

  1. Check your utilities

On finding that your boiler is not functioning correctly, you shouldn’t rush to conclude that the boiler is faulty. In some instances, your boiler might not be operating smoothly because the supply of essential utilities such as electricity and gas have been interrupted.

For instance, if you find that your boiler’s display panel is blank, the issue lies with the lack of electricity supply to the boiler. To confirm this conjecture, test your home’s lights and sockets to see if there is electricity. If they are functioning correctly, you should check your main fuse box to see if it is blown or has a tripped switch.

If there has been a recent power cut to your home or a local or regional power outage, then you should rest easy knowing that your boiler will return to normalcy once the power supply is restored.

Next, check whether the gas supply to your boiler has not been interrupted. You can quickly find this out by checking whether the other gas appliances in your home are functioning correctly. If, for example, your gas cooker isn’t firing up either, then the issue most likely stems from gas supply problems.

Lastly, check whether there is a steady supply of water to the boiler. Although this issue is often overlooked, it could be the reason why there is no hot water from your boiler. You can quickly tell if there is a water supply issue by placing your ear next to the boiler pump. Usually, you should hear water flowing through it.

If you can’t hear any sound of rushing water, you should consider calling a professional heating engineer. The engineer will identify the reason behind it and fix the issue, thus restoring your boiler operation to normal.

Reasons why there is no hot water from your combi boiler

Finding your boiler up and running yet failing to produce any hot water can be outright confusing.  However, this is a clear indication that there is no issue with your boiler’s utilities, but rather, the problem lies with your boiler’s settings or individual components of your central heating system.

Some of the most common issues that may result in your boiler not supplying hot water include:

  1. Pilot light problems

The pilot light in your boiler ignites the gas or oil, which in turn heats the water in your boiler. It is, therefore, safe to conclude that your boiler will not produce hot water unless the pilot light is on.

If you are unfortunate enough to have your boiler’s pilot light go out or just fail to catch, you might have to deal with an unwelcome cold shower. In the case of an old boiler model, you can easily tell when the pilot light is off as it is visible through the framework of the boiler. However, the pilot light is hidden from sight in modern boilers, and the only way you’ll know that it’s off is by reading the error code on the display panel.

Usually, you can relight your boiler’s pilot light by following the steps outlined in your owner’s manual. Then, if you are lucky, the issue will be resolved, and you’ll get back to enjoying hot water from your boiler.

If, however, the pilot light fails to reignite, or lights up and goes out again, then it is time you consider calling in the professionals. In most cases, the pilot light failing to catch is closely tied to a faulty thermocouple. The heating engineer will analyse the problem and tell you whether it is possible to carry out repairs or if you have to install a new one.

  1. Frozen pipes

If your boiler stops supplying hot water in the heart of winter and you find yourself having to contend with a cold shower, chances are high you have frozen pipes. In most cases, the pipe that is most likely to fall victim to this is the condensate pipe, as it is exposed to harsh external winter conditions.

If you’re wondering, the condensate pipe is a waste pipe that carries the condensation water from your boiler and drains it outside your home. During cold weather, the wastewater in the condensate pipe can freeze, therefore blocking the draining duct.

Once the condensate pipe freezes, the boiler will initiate an automatic lockdown procedure for safety reasons, hence the lack of hot water supply.

But the good thing is that the issue of a frozen pipe can be resolved quickly without involving the expensive services of a heating engineer. To fix this issue, you need to melt the frozen water in the pipe. You can achieve this by wrapping the affected pipe in a warm cloth or pouring warm water over the frozen area.

Make sure you do not use hot water as it might cause your pipe to burst. Once the ice has been thawed, you need to restart your boiler, and hopefully, it should be able to roar back to life.

  1. Faulty diverter valve

If you have a combi boiler, then you have undoubtedly heard of the diverter valve. Well, if you haven’t, the diverter valve is an essential component in your combi boiler that allows it to switch between hot water and heating roles.

If the diverter valve gets stuck on the central heating position or develops a fault, it will mean there will be no hot water supply to your hot taps.  In most cases, the issue of a defective or stuck diverter valve is attributed to natural system corrosion and sludge build-up in your boiler.

Even with the error code and boiler manual, fixing or replacing a faulty diverter valve is an intricate task that you can’t handle on your own. It is, therefore, advisable that you leave the issue to a certified heating engineer.

  1. Pressure issues

Too high or too low boiler pressure can result in your combi boiler not producing any hot water. Ideally, your boiler’s pressure should be within the green zone on your pressure gauge. If the needle points on the red zone, either below or above this green zone, your boiler is having pressure issues.

Luckily, boiler pressure is an issue that you can handle on your own. If your boiler is under-pressurised, you can follow the instructions on your owner’s manual to repressurise it. Just ensure that you halt the process when your boiler’s pressure rises to a value of around 1 to 2 bar.

On the other hand, if your boiler pressure is too high, you can bring it down to optimum levels by bleeding your radiators. If, however, this doesn’t resolve the issue, then your boiler might be broken. You should, therefore, contact a professional heating engineer right away.

Reasons why there is no hot water from your regular or system boiler

If you have a regular or system boiler fitted with a hot water storage cylinder, you are used to having a steady supply of hot water in your home. But during some days, you’ll be surprised to turn your hot taps and find there is no hot water.

Here are the common reasons why your system or regular boiler isn’t meeting its task of providing a steady hot water supply.

  1. Faulty thermostat or timer

In a quest to have more control over your home’s temperature and save money on energy bills, many people opt to install thermostats and timers on their boilers.

In most cases, the thermostat is exclusively linked to central heating and radiators, and a fault with it won’t affect your hot water supply.

If, however, you are using your central heating thermostat as a timer, you are likely to go without hot water and heating in your home if it develops a fault. For instance, if you set this thermostat to the lowest setting, you will likely have lukewarm water coming out of your hot pipes. Fortunately, this can be quickly resolved by adjusting the thermostat setting using the thermostat dial.

Another issue that can develop with this kind of thermostat is that you can find that you only have hot water when central heating is on. If this is the case, then you should consider calling a heating engineer right away.

If your boiler has a stand-alone timer, then you should check it to ensure it isn’t the one causing the hot water crisis in your home. Your timer may be to blame for your home lacking hot water because it is affected by factors such as accidental knocks and power supply issues.

Your boiler’s timer can also be reading the wrong time due to someone altering the clock, hence the reason why there is no hot water in your taps when it should ideally be there.

You can always check your boiler’s control panel to determine whether the boiler is currently running as per the timer. If it isn’t, and it is ideally supposed to, you can reset the timer by following the instructions in the timer manual.

  1. Small hot water cylinder

Well, have you stopped to consider the fact that you may have exhausted the hot water stored in your boiler’s hot water cylinder? This is particularly true if your family’s hot water demand is quite high and you’ve installed a small hot water cylinder.

Once the hot water stored in the cylinder is exhausted, you will have to wait until the next heating cycle, when the boiler will fire up and heat another tankful of water. If you don’t have the patience, you can override your boiler’s timer and start the boiler to maintain a supply of hot water.

Sadly, the issue of small water cylinder size can only be resolved by installing a standard-sized one that can sufficiently meet your family’s demand for hot water. But before you install a new hot water cylinder, you should talk to a heating engineer who will recommend the appropriate cylinder size for your home.

  1. Boiler or pipe leak

The presence of a leak in your boiler or hot water pipes will result in a drop in water pressure, which in turn will affect the delivery of hot water to your taps. This is because the leaking will result in loss of hot water en route from the boiler to the hot taps.

Although you can resolve the secondary issue of low water pressure by manually topping up your boiler, you should call a heating engineer to find the leak and solve the problem for good.

How to fix the issue

As much as no one wants to be stuck without hot water for a long time, there is no need to panic and call a heating engineer who will charge you a lot of money in repair costs. This is because some of the issues leading to your boiler not producing hot water are easy to solve on your own.

Here is the general action plan you should follow to resolve your boiler’s inability to heat water.

  1. Check your gas, water, and electricity supply.

As earlier said, hot water issues are not always tied to a fault with your boiler. Sometimes, the problem is with the supply of essential boiler utilities without which the boiler cannot operate. This is, therefore, the first place to start your quest to resolve the boiler’s inability to supply hot water.

  1. Check for error codes or fault codes.

Thanks to sophistication and modern technology, your boiler is now more capable of communicating its shortcomings via error codes. Usually, the boiler displays this fault code on the display panel or screen, and you need to decipher it using your owner’s manual to resolve the underlying issue.

If you have misplaced or no longer have your owner’s manual, there is no need to panic. You can always visit the boiler manufacturer website to crack these codes. And once you have deciphered what your boiler’s issue is, you can weigh whether to attempt DIY repairs or call a professional heating engineer.

  1. Inspect your boiler controls

If you still can’t find the issue plaguing your boiler and sabotaging hot water supply to your taps, then it probably has something to do with boiler controls. If you own a combi boiler, check and ensure that you haven’t accidentally set the boiler to heating only or adjusted your thermostat to the lowest setting.

You should also check your timer to ensure it is working and that the timing has been set correctly.

  1. Call a professional heating engineer

If you’ve tried all online remedies for a boiler not heating water and are yet to solve your boiler’s issues, then it is about time you seek expert help. Your first stop should be a professional heating engineer who will be able to troubleshoot and resolve the issue plaguing your boiler.

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