No Hot Water From My Boiler | How to Fix It Re January 20, 2022

No Hot Water From My Boiler | How to Fix It

Ariston Boiler

None of us wants to hear the dreaded words, ‘There is no hot water coming from my boiler’, especially if you live in colder areas, and definitely not during the colder winter months. Unfortunately a hot water bottle will not help either. 

There are a number of factors that could contribute to your boiler no longer heating water to your property, but don’t panic! This blog will look at some of the more common issues that can arise and how to fix them. This will be the ultimate troubleshooting guide that you can run through before calling your local Gas Safe Engineer. We are here to help you get to the bottom of this. 

Here are some of the most common issues that may be why your boiler is not heating your hot water.

1. Frozen Pipes

Typically, it is the condensate pipe that is connected to the outside of your home which can freeze. During the freezing temperatures, the water inside your condensate pipe can turn to ice, clogging your pipes. 

When your condensate piping freezes, your boiler will automatically shut off for safety reasons, leaving you without heating or hot water until you defrost the frozen piping.

To defrost your condensate pipe, pour warm water along the pipe and repeat the process until the condensate pipe is defrosted. Alternatively, use a hot water bottle or a heat pack to defrost the pipe. 

Tip – Don’t use boiling water as it could cause the plastic pipe to melt. Instead, boil a kettle and let it cool for 15 minutes.

These methods are very simple to carry out and are completely safe but if you’re not confident in attempting these or have a concern over having damaged your condensate pipe, it’s recommended to contact a qualified heating engineer.

Once the ice has gone, simply reboot your boiler to restore your hot water supply.

2. The Pilot Light

All boilers that burn fuel such as gas or oil require a working pilot light.

What is a pilot light?

A pilot light is an integral element. The flame ignites the gas that is provided to the boiler, which then heats our homes, our radiators and produces the warm water we wash with.

You may notice that on occasions, when your central heating system starts up, your pilot light may go out or fail to light up. When this issue occurs, this will result in a complete system failure, with no hot water coming from your boiler. 

If this happens, you can find help and a guide to relighting your pilot light in the back of the manual for your boiler. You can also find your boiler manufacturers’ boiler fault codes in our blog section on the WarmZilla website.  

In most cases, you’ll be able to fix this fault yourself and won’t need to call a registered gas safe engineer out at a cost to get things working again.

How do you relight the pilot light on a boiler?

If your boiler hasn’t got any clear instructions in the manual or on the appliance itself, try the following steps:

  1. Turn off the appliance and the gas control valve on your boiler (and any other appliances with pilot lights out if this affects multiple appliances). Don’t turn the gas to ‘pilot’ just yet.
  2. Wait around 10 minutes before you do any of the next steps: this ensures any gas that has built up can disperse. With all the gas safely dissipated, remove your appliance’s cover or door.
  3. Now you can turn the gas to ‘pilot.’
  4. Press and hold the reset switch for one minute and hold a flame to the pilot light at the same time.
  5. Ensure you only hold the switch down once the pilot light has ignited, to reduce the chances of any gas accumulating again.
  6. When you release the button, the flame should stay. If it goes out again, the re-ignition has not worked.
  7. If all is working as it should be, return any casing/doors and turn the gas from ‘pilot’ back to ‘on.’

3. Pressure Problems

Pressure problems can be a fiddly fault to deal with. In the best-case scenario, your boiler might have too low water pressure to move hot water around your home efficiently. 

If your pressure reads at less than 1 bar, you may have lost water from the system due to a leak. All you need to do in this situation is a one time top up with more water.

If the pressure reads at 2.75 bar or above, which is too high, you should look into bleeding your radiators. This will help to release the pressure and bring it back down to a suitable level. 

If you are going to attempt to bleed a radiator yourself, make sure that you have a way of catching the water to prevent the walls or floor from being ruined. 

Take caution when undertaking this job as the water can be very hot. If you’re unsure about anything, it’s a good idea to call a qualified engineer to assist you.

How do I check my boiler pressure?

At the front of your boiler, you will find your pressure gauge. When your boiler is off and cool, this is an easy way to check your boiler’s pressure. 

A hydraulic pressure gauge will indicate the following: 

  • Standard operating pressure with a green zone
  • Maximum safe operating pressure with a red zone

You may find that your boiler has a digital boiler pressure gauge, which will show you if the pressure is too high or too low by flashing the reading on the LCD screen. If you want to learn more about how to repressurise your boiler, we have this covered too, just click the link!

4. The Diverter Valve

An important component of boilers is the diverter valve. The diverter valve directs the flow of water between your central heating and hot water supply. If there is an issue or fault with your diverter valve, this will cause either your central heating system or your hot water system to fail. 

The problem is that you can’t do much about this problem on your own, so you’re going to need to get a qualified, gas-safe engineer in to fix it as soon as possible. Solving this problem can come at a cost, particularly if you are going to have to replace your diverter valve.

5. Your Thermostat

If you have got a relatively new boiler with a thermostat and a timer to control when you have hot water during the day, then a fault with your thermostat could cause your boiler to shut down completely, stopping you from getting hot water and a warm, cosy home. 

Thermostats are usually either wall or boiler-mounted and designed to regulate the temperature of your home. 

Thermostats allow you to set a preferred temperature for your home and will signal to the boiler that your boiler needs to maintain this heat whilst your central heating is on. If you start noticing that your boiler is not maintaining this heat, then there are a few things that can check:

  1. Do the batteries need changing in your thermostat? 
  2. Is your thermostat boiler controller too old for your current system?
  3. Is the temperature you’ve set too low? 
  4. Have you placed your thermostat in the wrong place? It must be away from any kind of heat source to work efficiently. 

6. Energy Source Problems

A very common explanation for a lack of water heating is a problem with either the power or gas supply to your boiler. Check your fuse box to ensure it’s not just a tripped fuse.

It is also worth checking that your boiler is actually switched on, and that the timer and that your thermostat isn’t set to the wrong settings. 

If any of your other appliances seem to be lacking power, then the best thing to do is to call in a gas safe engineer to help you sort this out.

7. Leaks in your Water Supply

No hot water coming from your taps?

This could be a result of a leak in your boiler or your pipes. 

A leak in your boiler or pipe will lead to a pressure drop, your pressure gauge crashing down to a low number, and no hot water coming out of the hot tap, as discussed above.

In general, you can fix low pressure by topping up your boiler manually, which we have a linked blog to help you with above. However, if it’s caused by a leak, then you’ll need to find a gas safe engineer to make sure everything is properly fixed up with no further leaks.

Where to check for a leak?

If you haven’t seen any definite signs of a leak but think there could be one, here are our top places to check. In these areas check for drips, anything that needs retightening, clearing up of any debris/sediment build up.

  • The drain valve – Head to the bottom of your hot water tank.
  • Spigot – Ask your Gas Safe Engineer if your valves need replacing?
  • Tank – Whatever the size, this can cause huge amounts of damage and is not something to be ignored.

In some cases, your Gas Safe Engineer may suggest that you need a system cleanse or powerflush to help remove any excess debris build up in your system.

8. Air In Your Pipes

Sometimes if you have no hot water, or your hot water is coming out in an inconsistent, spluttering manner this could be caused by airlocks in your pipes.

When air is trapped in pipes, it stops the water from coming out smoothly, if at all, and behaves like any other blockage. Removing airlocks can be done by attaching a hosepipe to the tap that isn’t working (in this case, a hot tap). Then fit the hosepipe’s other end to a working (in this case, cold) tap. Turn the hot tap on, followed by the cold tap.

The water pressure from the mains will push all of the airlocks out. Leave the taps running for a while to make sure the water is running smoothie again and then carefully remove the hose from the lower tap (to avoid creating more airlocks/vacuum).

9. Ball Valve Float Stuck

If you have a combi or system boiler, then you don’t have to worry about this. However, if you have a regular, conventional boiler system, then you will have an additional water tank in your attic, which has a ball valve float in it.

A ball valve float’s job is to detect water levels and control flow. Ball valve floats can get stuck and prevent any water from circulating through the system.

If you can see into the tank, check that the ball float valve is not stuck, then see if you can gently free the ball and see if water begins flowing again. If you can not see into your tank, we recommend that you call a local engineer for assistance.

10. No Hot Water To My Shower

In this more specific example, you may be getting hot water from your taps, but not in your shower. If this is happening, it is most likely down to another valve, known as the “mixing valve.” If this becomes stuck or is faulty, it will need to be replaced, but don’t panic, it’s not too expensive.

Another reason could be that if you have recently installed a new shower, the built-in anti-scalding device may be set too high, so the water is not being allowed to heat up enough. You can usually locate the anti-scalding device behind the tap/knob/switch which changes the heat of the shower.

11. No Hot Water- Electric Boilers

Many of the problems you encounter with gas boilers, you will not encounter with an electric one.

While they are more reliable than gas boilers, they are not always perfect so from time to time electric boiler users can find themselves with no hot water.

Due to the nature of electric boilers and the fact they are supplied by high voltage electricity the risks can be just as dangerous, if not more so, than gas boilers.

What you need:

  • To work on these types of boilers you must ensure you are capable of doing so. Ensure there is not a general problem with power in the house or area first.
  • Reset your fuse box, if necessary, and see if your boiler returns to normal. If it doesn’t, before starting work, you must turn the power off to your boiler.
  • Next, ensure you have the right electricity testing tools to help you do the job safely.
  • Do not attempt to work with electricity if you are not confident using testing tools like this.

Elements to check:

Circuit breaker
If your fuse has blown or the circuit has tripped, you can usually just replace the fuse or reset the circuit breaker. If your boiler continues to trip you will need an electrician.

Heating elements
Depending on the model of your electric boiler, you will have one, two or even more heating elements. Check these elements using any tool that detects the voltage. Usually, there will be one place in the upper end and this heating element has a knock-on effect on the lower one.

If you have no hot water at all, this will be indicative of the thermostat problems mentioned above, or a problem with the “upper” element. If your lower element breaks, you should be able to still get a bit of hot water.

Check both elements with your element tester, in order to be sure and also make sure they are grounded.

12. Are You Due a Boiler Service?

Many boiler manufacturers will void your warranty if you do not follow procedures and have your boiler serviced annually. It is important to keep on top of maintaining your boiler because this will ensure that any small issues can be sorted before they become a bigger, more costly problem. While a service might not fix your issues, they could prevent them from happening in the future.

If you have checked all of the above, and you find that there is still no hot water coming from your boiler, then we recommend getting professional advice from a qualified Gas Safe Engineer. Here at WarmZilla, we have Gas Safe Engineers that can assist you on our live chat. If you would prefer to hear from them, head over to our website and click the live chat option in the bottom left corner.

We hope that this troubleshooting guide has helped you to identify the issue that may be causing your boiler to not provide your home with hot water.


This could be due to many reasons, to name a few; frozen pipes, low pressure, thermostat issues, energy source problems, leaks in water supply, etc.

A pilot light is an integral element. The flame ignites the gas that is provided to the boiler, which then heats our homes, our radiators and produces the warm water we wash with.

At the front of your boiler, you will find your pressure gauge. When your boiler is off and cool, this is an easy way to check your boiler’s pressure. 

A hydraulic pressure gauge will indicate the following: 

    • Standard operating pressure with a green zone
    • Maximum safe operating pressure with a red zone
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