Why does my boiler have no hot water, but heating works?

If you are facing an issue with your boiler system where the heating system is working, but it does not have hot water. It is a common and fixable issue that most boiler users face. Sometimes it becomes an irritating problem that the central heating works perfectly, but the taps do not have hot water.

About Your Boiler Works

Different kinds of boilers are available in the market, where most modern homes use one of these boiler types-

Combi boilers

System boilers

Conventional or regular boilers

Hot water and central heating operate through different components, even though they come from the same boiler. This means one function can fail while the other continues to work normally.

Common Reasons Your Boiler Has No Hot Water but Heating Works

Faulty Diverter Valve

The diverter valve is a very common issue that controls whether hot water goes to your taps or your radiators.

• If the valve gets stuck or fails

• Hot water may continue to flow to the radiators only

• Taps will stay cold

• There will be some basic signs of a diverter valve problem, like

• Heating works normally

• No hot water from taps

The boiler fires up when heating is on, but not when taps are opened

In these situations, you need to call a professional repair or replacement to change a diverter valve because these kinds of issues are not a DIY fix.

Boiler Thermostat or Temperature Settings

The boiler thermostat or temperature setting is surprisingly simple, like

The hot water temperature may be set too low

The boiler may think the water is already hot

The heating thermostat works independently

You should review for some expected mistakes, such as the hot water temperature dial on the boiler and digital boiler control panel settings. If there are any points, you need to fix this situation and raise the hot water temperature (around 50–60°C) and test it again.

Faulty Hot Water Thermistor

A thermistor works to estimate water temperature and reveals when to heat water. If the system is not working properly or it is faulty, then the boiler won’t heat water for the taps, but heating may still work fine.

There are basic signs that the hot water thermistor is not working properly, like-

No hot water despite normal boiler pressure, and the boiler doesn’t respond when the hot tap is turned on. For handling this kinds of situation, you need to call a professional expert to handle this situation and replace the water thermistor.

Low Boiler Pressure

Low pressure in some systems can impact hot water more than heating.

The ideal boiler pressure must be between 1 and 1.5 bar, and pressure must be below 1 bar may cause hot water failure. You should check the pressure gauge on your boiler system.

If there is an issue, you should get connected to Fixhelpia, where our expert will easily fix this problem by re-pressurising the boiler using the filling loop by following the manufacturer's instructions.

Limescale Build-Up

Over time, limescale can block the boiler system, which can cause issues for

• Heat exchangers

• Pipes

• Sensors

This restricts hot water flow while heating still functions.

There will be some warning signs, like-

• Hot water runs lukewarm

• The boiler makes kettling or banging noises

Here, a professional engineer will help with power flushing or descaling this issue.

Broken Diaphragm or Internal Valve

In some boilers, a rubber diaphragm helps detect water demand.

If it’s damaged, the boiler won’t activate for hot water, and heating continues to operate. Component replacement by a trained boiler technician.

Faulty Flow Sensor or Flow Switch

Combi boilers depend on a flow sensor, which works to detect when a hot tap is turned on. If it is not properly set or there is any issue, then the boiler doesn’t acknowledge the demand for hot water, or heating remains unchanged. To resolve this problem, you should get connected with a professional expert.

Frozen Condensate Pipe (Winter Issue)

During cold weather, condensate pipes may freeze, and the hot water function can stop first, and the boiler shows error codes, and there will be no hot water during freezing temperatures. If you are getting the same sign, in that case, you should carefully loosen the pipe using warm water.

How to Fix This Issue

You can safely check some error points, like-

• Boiler pressure

• Temperature settings

• Error codes on display

• Frozen condensate pipe

If any of these issues are found, you should not do-

• Internal repairs

• Gas-related components

• Electrical parts

These kinds of issues must be handled by qualified professionals for safety and warranty reasons.

When Should You Call a Boiler Engineer?

You should contact FixHelpia if:

• Hot water doesn’t return after basic checks

• The boiler shows error codes

• Pressure keeps dropping

• You hear unusual noises

• The issue keeps recurring

Ignoring the problem may lead to costly damage or complete boiler failure.

How FixHelpia Can Help

At FixHelpia, we specialise in different services, like-

Boiler diagnostics

Hot water repair

Diverter valve replacement

Emergency boiler services

Annual boiler maintenance

Our trained engineers ensure the best services with

Safe repairs

Fast response

Long-term solutions

Transparent pricing

How to Control Hot Water Issues with Easy Steps

Regular maintenance can save you stress and money. You need to be active for some self-control activities, like-

• Schedule annual boiler servicing

• Descalcify the system if you live in a hard water area

• Check pressure monthly

• Don’t ignore minor boiler issues

• Install a magnetic filter if recommended

Note: If your boiler has no hot water but heating works, the issue is due to any internal components like the diverter valve, thermistor, or flow sensor. For reliable, fast, and affordable boiler repair services, FixHelpia is here to help. Don’t let a cold shower disrupt your day. You can get your boiler checked by experts you can trust.