What To Do If You Have No Hot Water

If your boiler is producing no hot water, you need to read this guide. We will outline all the main causes of this problem and explain how to fix them. It should only take you five minutes to read, but this could save you a ton of money on repair fees and even let you enjoy that warm shower after all.

There is nothing worse than turning on the shower or running a bath and finding out that you have no hot water.

There are all sorts of different reasons why your boiler might not be generating enough hot water. In this guide, we have highlighted the most common and tried to break things down into sections, so you can just flick through to the issue that sounds most relevant to you.

Not every possible cause for a loss of hot water is covered here, but we are confident that the most common ones are, so there is a good chance you will find a fix for your issue.


Issue 1: No Hot Water But Heating Works

If your boiler is not generating enough hot water but your central heating is still working fine, the problem is most likely to be caused by a faulty diverter valve. This is not always the cause, but in our experience, it is in most cases.

How to Fix it:

You will need to get a qualified engineer out to fix a problem with a diverter valve. If you are lucky, the problem will be caused by some kind of blockage. Your engineer will be able to clear out anything that has become stuck and the issue should be resolved.

If, however, there is a more significant fault, you will probably have to shell out for a replacement valve. This is not going to be cheap and could set you back several hundred pounds.

If this is the recommended fix, and your boiler is already old and out of warranty, you will probably be better off spending a little more on a whole new energy-efficient boiler.

Do make sure the problem is definitely being caused by the diverter valve before going down this route though. There are other things, such as a faulty S-plan, Y-plan or zone valve that can cause the problem. These issues are much less common, but they do happen.

Issue 2: No Hot Water But Cold Water Works

If you are getting no hot water, but the cold water is working fine, your problem could be caused by a number of different things.

It could be as a result of many of the problems listed elsewhere in this guide, so be sure to read through the other sections carefully too.

The problem could even be as a result of something unrelated to the boiler. For example, if you have turned off the gas valve, your boiler will have no fuel and will, therefore, stop generating hot water but you will still have cold water.

Also, if you attempted to increase the pressure of the boiler using the filling loop and closed off more than one valve, you might have inadvertently left the water supply to the boiler switched off, so your boiler has no water to heat up.

How to Fix it:

To create hot water, your boiler needs both a gas supply and a water supply. If either of these have been switched off, there is no way your boiler can make hot water, so check both of these supplies first.

If there is no water at all, you should also check the main stopcock as this could have been turned off too.

If none of these things solves the problem, you should read through the rest of this guide as one of the other faults mentioned is the most likely cause of your problem.

Issue 3: No Hot Water In Your Shower Only

If you have no hot water in your shower but it seems to be fine elsewhere, the issue is almost certainly with the shower unit itself rather than the boiler.

There are a couple of possible causes for this. Either the mixing valve in the shower is either broken or jammed in some way, or your showers anti-scalding device is at the wrong setting.

How to Fix it:

If the problem is with the mixing valve, you will need to get this component either repaired or replaced. Given the complexities of a repair, it is almost always cheaper and simpler to opt for a replacement.

You will probably need to get an engineer out to carry out this repair and it involves rather fiddly work inside your shower.

If you have a newer shower, it is likely that it will have a built-in anti-scalding device. However, if this has been set too high, it can prevent the water from heating up to a sufficiently warm temperature.

The anti-scalding device on most showers is located behind the knob or dial used to adjust the heat of the shower. This dial can usually be removed and you should be able to adjust the anti-scalding device yourself without the need for professional help.

In all honesty, the first issue is more likely to be the cause of the problem than the second one but is worth checking your anti-scalding device before calling on an engineer.

Issue 4: No Hot Water And No Central Heating

The biggest and most common issue of all is when you find you have no hot water and no central heating. This is a problem that can be caused by all manner of different things and it can be difficult sometimes to pinpoint the precise issue.

However, there are a number of possibilities that commonly cause this problem, which we have outlined below:

#1 – No Power

If your boiler is not generating any heating or hot water and the control panel on the front is blank, with no power lights showing, the most likely issue is that your boiler has no power supply.

How to Fix it:

There are a number of reasons why you might have no power to your boiler, so it is worth working through this list to see if any apply to you:

  • A fuse might have blown in your boilers plug or socket. Replace this and the boiler should begin working again.
  • A trip switch has been triggered in your fuse box. Resetting this should restore power.
  • There is a wider power cut. This should mean your lights and sockets aren’t working either. You will have to enquire about this issue with your electricity provider.
  • Your electricity meter has run out of money. Topping up your credit should see your power restored and your boiler start to work again.

If none of these is the issue, it could be a more fundamental issue with a key component in your boiler, such as the printed circuit board (PCB). This will require the help of an engineer and could prove costly.

#2 –Pilot Light Has Gone Out

The pilot light is the name for the small flame that you can always see through the front of your boiler. If the pilot light is out, the boiler will not be working.

An extinguished pilot light is usually accompanied by an error code on your display panel, although there are several possible codes with each manufacturer.

How to Fix it:

The pilot light could go out as a result of a bit of dirt or debris blocking it up or because the component itself has a fault. Equally, it could also be caused by a problem with your gas supply.

Whatever the reason, you will need to summon the help of a qualified Gas Safe engineer to examine your boiler and fix the issue.

#3 – A Faulty Heating Pump

Your boiler’s heating pump is an essential component that pushes hot water around your central heating system. When it is working properly, you should feel that the flow pipe coming out of the bottom of your boiler is hot and the return pipe is cooler.

If this is not the case, it is likely that there is a problem with the pump that makes this water circulate.

How to Fix it:

This problem could be caused by a problem with the pump itself. This component can get blocked up with debris which stops it working properly or it could be that one of the seals in the pump has failed. You will need to get an engineer to take a look and they will either be able to clean out the debris or recommend a fix.

The problem could also be caused by a blockage elsewhere in your central heating system. A hot flush should be sufficient to clear this, but again you will need to get an engineer to carry this out for you.

#4 – Frozen Condensate Pipe

In cold weather, a common problem that can shut any boiler down is a frozen condensation pipe. All boiler produce condensation which is usually released to the outside of the property.

However, in cold weather, this pipe can freeze. This means there is nowhere for the condensation to go and as a result, the boiler is forced to shut down rather than risk water damage to key components.

How to Fix it:

This is a simple issue that you can fix yourself. Locate the condensation pipe and use warm (not hot) water to melt any ice that has built-up.

Check the pipe for any other possible blockage and then lag it with some insulation to help prevent the problem from reoccurring.

#5 – Low Pressure Or No Pressure

A loss of pressure is a common problem with many boilers. There are various things that can cause low or no pressure in a boiler, but the most common reason is a leak somewhere in the boiler or the wider heating system.

How to Fix it:

The simplest way to fix this issue is by identifying the source of the leak and patching it. There are various DIY kits available to help you do this but if you are not confident with such work, you are best to get an engineer to do the job for you.

Boilers can be repressured manually using the filling loop which is located inside your boilers case. This will solve the problem temporarily, but unless you fix the leak too, the pressure will just drop again.

ALSO READ: High Boiler Pressure, How to Fix It

#6– Faulty Printed Circuit Board / Display Panel

When you listen to your boiler, if you can hear the components working but it still isn’t generating any heat or hot water, the most likely problem is with your Printed Circuit Board (PCB).

This is a major issue as the PCB is difficult to repair and expensive to replace.

The problem could also be with your display panel which can break down or be damaged by leaking water.

How to Fix it:

If there is a problem with the display panel, this can usually be replaced relatively affordably. A replacement is invariably more economical than a repair.

If the PCB has a problem, you are likely to be looking at a bill of £500+ for a repair. If you have an older boiler without a warranty, your best bet would be to consider buying a new energy-efficient boiler instead.

The PCB going is an indication that your boiler is on its last legs and buying a new boiler through a site like WarmZilla is likely to end up saving you money in the long run.

#7 – Faulty Programmer or Timer

Another fairly common cause of your boiler not producing either water or heat is an issue with either the timer or the programmer.

Both of these components can go wrong either through age, wear and tear, or if you have had a power cut.

How to Fix it:

The first thing to do is reset the timer and programmer to see if this solves the problem. Details on how to do this vary from one boiler to another, so you should check your boiler manual for instructions.

If you have had a power cut, this can interfere with the time and date stamp on both of these components and if you have programmed times for your heating and hot water to come on, this could have been disrupted.

Check whether these are correct and if not, reset them. This should resolve the problem.

#8 – Boiler Lockouts

All boilers will lockout as a failsafe measure if they identify a problem which could make the boiler unsafe or risk damage to other parts.

Lockouts can be caused by all sorts of different reasons. There will almost always be an error code indicated on the boiler display panel and this will usually, but not always, give an indication of what is causing the lockout.

How to Fix it:

Identify what the error code means by consulting your boiler manual or the internet. Once you have done this, you should be able to work out the best cause of action. Take a look at the other articles on our site for more specific advice and if in any doubt, we strongly recommend consulting a qualified engineer for advice.

Where to buy a new boiler

If the cause of no hot water relates to a serious issue with your boiler, and you have a boiler which is already old and out of warranty, you might want to consider buying a new energy-efficient boiler rather than spending large sums patching up your old boiler.

If this is the case, you should always get multiple quotes on a new boiler and we would strongly suggest you get one of these quotes from WarmZilla.

WarmZilla is an online boiler installation service that operates across the UK and is able to offer some of the best prices around on a wide range of boilers from all the top manufacturers. They offer have special deals and exclusive offers available too.

WarmZilla is one of the best online boiler services around and it is well worth taking a look to see how much they can save you on a new boiler.


There are a lot of different things that can cause you to have no hot water. In this guide, we have highlighted the most common causes and explained the faults behind them. We have also indicated the best ways to fix them.

If the problem is a major issue with an old boiler, we have recommended you opt to invest in a new boiler rather than patching up your old one. WarmZilla is our suggestion of a place to get the lowest quotes available on a wide range of boilers from all the top manufacturers.

Have you had problems with your hot water supply? Did our guide help you resolve it? Do you have any questions or tips that we have missed out in this guide?

We always welcome the input of all our readers and try to respond to everyone, so do share your thoughts with us using the comment box below.

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