Hot Water But No Heating?

Hot water but no heating? Your taps stream hot water, yet your house remains cold? 

Understanding and troubleshooting this common issue is essential, especially as the UK’s colder months approach. 

In this article, we’ll provide the common issues that cause hot water but no heating and the solutions.

Common Causes & DIY Solutions

Here are some common causes if you have hot water but no heating, and solutions you can undertake yourself (remember, if you’re unsure, call out a Gas Safe Registered engineer)

Thermostat Settings

The thermostat senses your home’s temperature and maintains it at a desired set point, turning the heating on or off based on the room’s temperature relative to your chosen setting.

Incorrectly set thermostats are the most common cause of hot water but no heating.

Ensure you know how to set your thermostat and read the instructions, and if you still need the instructions, you should be able to download them online.

Ensure that your thermostat is set to a temperature higher than the current room temperature and is in the ‘heat’ or ‘auto’ mode. 

Also, remember that a thermostat near a heat source or in a sunlit area might register a room as warmer than it is, not triggering the heating.

Timer/Programmer Issues

The timer, often referred to as a programmer in heating systems, is designed to switch your heating or hot water on and off at predetermined times throughout the day, allowing you to schedule when you want your heating on.

Double-check the timings, especially after power cuts or daylight saving changes. 

If your programmer doesn’t turn on the heating when set, it might need a replacement.

Thermostatic Radiator Valves

Thermostatic Radiator Valves (TRVs) regulate the heat of individual radiators. 

Ensure they’re turned on and at the right setting. TRVs can sometimes become stuck, preventing the radiator from heating. A stuck TRV can be turned up and down a few times to free it. 

If our TRVs are still stuck, they must be unstuck manually.

Boiler Settings

Your Boiler is the heart of your home’s heating system. Sometimes, Boilers have settings that separately control hot water and heating. 

Consult the user manual and take a look at the Boiler controls. Ensuring your Boiler is set to heat your home.

Boiler Fault Codes

When modern Boilers encounter issues, they often display fault codes. Check if your Boilers display any codes and cross reference with your Boiler’s manual. If the Boilers are at fault, a code will explain the issue and tell you what to do next.

Boiler Pressure

Your Boiler pressure should be between 1-2 bars (consult your Boiler manual). If the pressure is too low, your heating might not work. Check your Boiler pressure and repressurise if necessary.

Airlocks in the System

Pockets of air will obstruct the flow of hot water in your radiators, preventing correct heating of your rooms. If your radiators are cold at the top but warm at the bottom, bleed your radiators to release trapped air.

Common Causes & Solutions That Require The Attention Of A Gas Engineer

The following are some common causes of hot water but no heating. However, a qualified Gas Safe Registered Engineer must undertake the solutions presented.

Diverter Valve

The diverter valve in Combi Boilers determines the hot water route, deciding between radiators or taps. 

If the diverter valve malfunctions, it might be stuck in the water mode, preventing your radiators from heating. 

A Gas Safe Registered engineer can repair or replace the diverter valve to restore your heating.

Pump Problems

An incorrectly set or malfunctioning pump will prevent your radiators from heating. 

Inspect your pump and, if necessary, turn the speed up. 

If your pump is set correctly and you still have no heating, then it may need replacing by a heating engineer. Symptoms of a faulty pump include leaking, loud humming noises or being hot to touch.

Fuel Supply

Gas, Oil or LPG are required to power a Boiler, provide hot water and heat your home. Without fuel, they won’t run.

Many Regular and System Boilers have an immersion heater fitted to the cylinder, so they can still provide hot water even if the Boiler isn’t working.

If you have a gas-powered Boiler, an engineer can check for an issue with the supply. If your Boiler runs on Oil or LPG, check it has yet to run out.

System Sludge and Debris

Over the years, sludge can accumulate inside your heating system. This debris can hinder water flow and prevent radiators from heating. In such cases, a Powerflush may be required to restore your radiators to full working order.

Preventative Measures & Maintenance Tips

Prevention is always better than cure. Regular maintenance, including annual Boiler and cylinder servicing and periodic checks of central heating components, will ensure you don’t run into the problem of hot water but no heating.

Need Help?

TM Hughes And Son Gas Services Ltd have a team of Gas Safe registered engineers serving Essex. 

If you can’t solve your hot water but no heating issue with the tips presented in this article and live in Essex, please contact us. We can help you.