It can be frustrating when your Worcester boiler provides hot water but there is no heating. This problem often leaves homeowners confused about where to start troubleshooting. The good news is that there are several things you can try yourself before calling an engineer.
This article will walk through the common causes and solutions, like checking boiler pressure, bleeding radiators, assessing the thermostat, resetting the boiler and investigating whether the diverter valve or motorised valve have failed. Follow our tips below to get your Worcester heating working again.
Check Boiler Pressure
One of the first things to check when your Worcester boiler provides hot water but no heating is the boiler pressure.
The boiler pressure refers to the amount of pressure in the sealed system. It needs to be within a certain range for the boiler and heating system to operate properly.
On a Worcester boiler, the pressure gauge will be located on the front of the boiler. Check that the needle is in the green section, between 1 and 2 bar pressure.
Low pressure is a common cause of hot water but no heating. It prevents the boiler from circulating hot water to the radiators.
| Problem | Solution |
|---|---|
| Pressure below 1 bar | Use the filling loop or integral filling key to top up water in the system until the gauge reads between 1 and 2 bar |
| Pressure dropping rapidly | May indicate a leak in the system. Turn off the boiler and contact an engineer |
To increase pressure on a Worcester boiler:
- Locate the filling loop or blue handle filling key
- Attach the loop or key and turn to open
- Allow water to flow into the system until the pressure gauge reads between 1 and 2 bar
- Close the loop or key and detach
This simple step can get your heating going again. Keep monitoring the pressure gauge. If it continues to drop, a leak is likely. Prevent further damage by switching off the boiler and calling an approved heating engineer to investigate repairs.
Check Thermostat
The thermostat controls your Worcester boiler heating system. Before looking at faults with the boiler itself, it’s worth checking whether the issue lies with the thermostat settings.
A common cause of hot water but no heating is that the thermostat has been turned down or switched off completely.
- Locate your thermostat (usually in a hallway or living area)
- Check the temperature set point – this should be around 20°C
- Verify that timers/schedules are correctly set
- Switch between modes (auto/on/off) to test heating
- If non-responsive, reset by holding down power button
For smart thermostats like Hive or Nest, use the app or online dashboard to:
- Check set point temperature
- Review heating schedules
- Check if eco mode is on
- Reset the thermostat remotely
| Issue | Solution |
|---|---|
| Battery flat | Replace batteries |
| Display blank | Try rebooting, check power supply |
| Heating unresponsive | Try remote reset via app |
If adjusting the thermostat settings and rebooting doesn’t restore heating, the issue lies with the Worcester boiler itself, not your temperature controls. Common boiler issues include lack of boiler pressure, stuck diverter valve or motorised valve failure.
Reset Boiler
If your Worcester boiler is providing hot water but there is no heating, one quick thing to try is resetting the boiler.
Resetting the boiler will clear any minor glitches and restart the system. It’s always worth trying this before calling out an engineer.
- Locate the reset button on the front of the boiler
- Press and hold for 5-10 seconds until the display goes off
- Wait for the boiler to restart and run through its startup checks
- Check if heating is restored
For combi boilers like the Worcester Bosch Greenstar range, the reset button is usually blue and found on the front panel.
Caution: Only press the designated reset button. Never interfere with sealed components on the boiler.
Resetting the boiler may dislodge any stuck components like the diverter valve and get the heating working again. However, if the issue persists, there is likely an underlying fault that requires engineer attention.
| Fault | Solution |
|---|---|
| Persistent loss of pressure | Leak in sealed system |
| Noises/banging | Airlock or sludge buildup |
| Heating stops after reset | Valve or pump failure |
Diverter Valve
On combination or combi boilers like those made by Worcester, the diverter valve switches the flow of hot water between heating the radiators and supplying hot water from taps.
If this valve gets stuck or fails, it can cause the boiler to supply hot water but not heating.
The diverter valve uses a small electric motor or electromagnet to operate. After years of use, scale and sludge can prevent the valve from moving between its two positions:
- Heating mode – valve diverts hot water to radiators
- Hot water mode – valve diverts hot water to taps
When the valve is stuck in the hot water position, the boiler will continue to provide hot water to taps, but the radiators will remain cold.
| Symptom | Cause |
|---|---|
| Hot water but no heating | Diverter valve stuck in hot water mode |
| No hot water but heating works | Diverter valve stuck in heating mode |
Resetting the boiler can sometimes dislodge a stuck diverter valve. But a new replacement valve may be needed. This requires draining the system and the expertise of a Gas Safe registered heating engineer.
If your Worcester boiler is producing hot water but failing to heat radiators, contact a qualified engineer to diagnose if the issue is a faulty or stuck diverter valve. They will be able to advise if the valve can be repaired or needs replacement.
Motorised Valve
Another important component in Worcester boilers is the motorised valve. This controls the flow of water in the central heating system.
A faulty motorised valve can prevent hot water reaching radiators while still supplying hot water to taps.
Inside the boiler, the motorised valve has a small electric motor that operates a pin that opens and closes the valve.
Over time, the motor or pin can fail causing the valve to get stuck in one position.
If stuck open, it will cause a loss of boiler pressure. Stuck closed, it will block hot water flow to the heating system.
Symptoms of a faulty motorised valve:
- Hot water but no heating
- Heating is intermittent or in some radiators only
- Boiler pressure fluctuates
- Boiler makes noises when heating switches on
Resetting the boiler can sometimes get a stuck motorised valve moving again. But often a new replacement is required.
As this involves draining down the system and disconnecting pipes, it requires the skills of a qualified Gas Safe heating engineer.
Boiler Replacement
If your Worcester boiler is more than 8-10 years old, an underlying issue may be that the boiler itself is reaching the end of its operational life.
Faults like losing pressure and noises when heating up, alongside the lack of heating even after resetting and topped up boiler pressure can indicate your boiler may need replacing.
Here are signs your Worcester boiler may need replacing:
- Regular loss of pressure
- Strange noises or banging
- Heating breaking down frequently
- Higher than normal energy bills
- Age over 10 years
- Visible corrosion or rust
Rather than paying for further repairs, a new A-rated boiler may prove a better investment.
Benefits of a new Worcester or alternative brand boiler:
- Improved reliability
- Energy efficient – lower bills
- Quieter operation
- Lengthy warranties
- Advanced controls
Installation costs can be offset through lower maintenance and fuel costs. Speak to accredited heating engineers about:
- Boiler grants or finance options
- Choosing the best new boiler
- Installation and trade-in offers
Key Takeaway – If your old Worcester boiler is causing endless issues, it may be time to replace it.
Conclusion
Having hot water but no heating from your Worcester boiler can be frustrating. But there are several things you can try yourself before calling an engineer:
- Check boiler pressure – Top up if low
- Bleed radiators – Release trapped air
- Inspect thermostat – Adjust settings/reset if needed
- Reset the boiler – Press reset button to reboot
- Monitor over time – Take note of any noises or leaks
With some practical troubleshooting steps and the expertise of heating engineers when needed, you can get your Worcester boiler heating your home again.