Why Is There No Hot Water from My Boiler?

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No one likes a blast of freezing cold water when they step into the shower, but if something goes wrong with your boiler this could well be how you find out about it.

Boilers are responsible for keeping our homes warm and ensuring that hot water flows from the tap whenever we need it. Unfortunately, if something goes awry within your heating system it usually means a lack of heating or hot water (or both), and finding out why isn’t always as simple as it sounds. But don’t worry, our boiler repair team is always on hand to help identify the problem and get your boiler working again.

Depending on your boiler type, there are a few common culprits for a lack of hot water. Read on and we’ll take you through some of the main faults that could be affecting your hot water supply.

Common Causes of a Lack of Hot Water from Combi Boilers

If you have a combi boiler, you might run into issues due to faults affecting your diverter valve – or frozen pipes could well be the problem. Other commonly reported problems that tend to mean no hot water are issues with the pilot light and incorrect levels of pressure in the system.

The pilot light isn’t working

The pilot light ignites the fuel your boiler runs on, so if it fails to light then your boiler will quickly grind to a halt.

Modern boilers will alert you to this problem with an error code displayed on the screen. If your boiler is older you may even be able to see where the flame should be, so you’ll know if it isn’t lighting up as it should. 

The diverter valve has failed

Your boiler’s diverter valve sends water wherever it’s needed in the heating system. When hot water is required, it will deliver water straight to the taps. And if it fails, you could well be left with a lack of hot water from any hot tap in the house. Thankfully diverter valves can usually be replaced, so you’re unlikely to need a new boiler if this happens. 

Your pipes are frozen 

Frozen pipes are one of the most common reasons for a lack of heating and hot water during the coldest months of the year. If the condensate pipe freezes, your boiler will stop working immediately. 

This is one of the only boiler-related issues that is possible to safely fix yourself, as it’s just a case of warming the affected pipe to melt any frozen water trapped inside. Once the frozen water has gone, the boiler should work again. 

Incorrect pressure in the system

Hot water is often affected by pressure in the system. There could be too little pressure, or pressure levels might have risen too high for the boiler to work safely. 

If there isn’t enough pressure, you may be able to fix the problem with a simple top up. High pressure levels often need the attention of an engineer, as this tends to mean a part isn’t working as it should. 

Issues that Often Mean No Hot Water in a System Boiler or Regular Boiler

Regular or system boilers are more commonly affected by issues like a broken thermostat or interruptions in energy supply to the boiler itself. Leaking pipes can also mean a lack of hot water, as can a water cylinder that simply isn’t big enough for a family’s day to day usage. 

Water is leaking from the pipes 

If you’ve got a leak somewhere in the system it might not be immediately obvious. But over time a leak will mean a lack of hot water as your boiler won’t be able to maintain the pressure it needs to send hot water through to taps. 

Check your pressure to see if it’s dropped. If it has, make sure you look for leaks before topping up the system. 

Your cylinder isn’t big enough for your requirements 

You might find yourself faced with no hot water if your water cylinder isn’t big enough for your family’s day to day needs. In this scenario, you will have had hot water initially, but by the time the last family member stepped into the shower it simply would’ve run out. 

Before assuming there’s a fault in your system, make sure that your cylinder is big enough for your requirements. If it isn’t, it might be time for an upgrade

There’s a problem with your electricity or gas supply  

Issues affecting your gas or electricity supply quite often mean an interruption to the energy supply to your boiler. So before you start thinking that your boiler isn’t working, check that you still have gas and electricity by trying other appliances nearby. If there’s a fault with the supply of either of these, you can rest assured that your boiler is working – you’ll just need to wait for the service to return to normal. 


If you’ve got no heating or hot water, we’re only a phone call away. Get in touch with a member of our team and we’ll send an engineer straight out to you. 

We understand that heating and hot water problems always need to be fixed quickly, so we’ll give you a time when one of our gas safe engineers can visit and before long we’ll have the issue resolved. Just contact us to find out more.