How to Fix a Central Heating Pump
Last updated: 30 September 2026
Check the pump is running, bleed it, check the speed setting, and replace it if seized.
Overview
A faulty central heating pump can stop your radiators from heating. This guide covers diagnosing and fixing a central heating pump.
Step-by-Step Fix
Before beginning any repair, ensure you have isolated power or water supplies. Clear your workspace, gather standard hand tools, and wear appropriate personal protective equipment (PPE).
- Turn off the heating system at the thermostat or programmer and allow the system to cool. Turn off the power to the boiler at the fused spur or the consumer unit. Confirm the power is off before you work on the pump. Place a towel under the pump to catch any drips.
- Identify the pump which is usually located near the boiler or in the airing cupboard. The pump has a large silver or black motor head and two pipe connections. It may have a speed selector switch on the side.
- Listen for the pump running when the heating is on. A working pump produces a soft humming sound. If the pump is silent it may not be receiving power or the motor may be seized. If the pump is very noisy the bearings may be worn.
- Check the pump is receiving power. Use a multimeter to test the voltage at the pump terminals. If there is no voltage the fault is likely with the wiring or the boiler control board and not the pump itself.
- If the pump is receiving power but not running it may be seized. Many pumps have a large silver screw in the centre of the motor head. Remove this screw and insert a flat head screwdriver into the slot underneath. Turn the screwdriver gently to free the impeller.
- If the pump is running but the radiators are not heating check the pump speed setting. Most pumps have three speed settings. Try setting the pump to the highest speed and see if the heating improves. If it does the pump may be undersized or the system may have flow issues.
- If the pump is noisy or leaking it may need to be replaced. Close the isolation valves on either side of the pump to isolate it from the system. Drain the pump by opening the bleed screw. Disconnect the wiring and unscrew the pump body from the valves.
- Install a new pump of the same size and specification. Connect the wiring following the manufacturer instructions and open the isolation valves to refill the pump. Bleed the pump and system then restore power and test the heating.
- If you are unsure about any step or if the pump replacement involves working on the boiler or the sealed system call a Gas Safe registered engineer. Central heating pumps are part of the sealed system and require care to replace safely.
Common Symptoms & Diagnostic Resolutions
Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.
| Symptom / Code | Likely Root Cause | Recommended Resolution |
|---|---|---|
| Pump is silent and no heat | Pump not receiving power or motor seized | Check for power at the pump terminals. If power is present free the impeller using a flat head screwdriver in the centre screw. |
| Pump is very noisy | Worn bearings or air in the pump | Bleed the pump to remove air. If the noise persists the bearings are worn and the pump should be replaced. |
| Pump leaking from body | Worn seal between motor head and pump body | The pump seal can be replaced but it is often more cost effective to replace the whole pump. |
| Heating works but is very slow | Pump set to low speed or partially blocked | Increase the pump speed setting. If the system is still slow the pump or system may have a blockage that requires flushing. |
Frequently Asked Questions
How do I know if my central heating pump is faulty?
Signs of a faulty pump include no heating noisy operation a pump that is silent when the heating is on or a pump that is leaking. You can also feel the pump body and if it is hot but not vibrating it may be seized.
Can I replace a central heating pump myself?
Yes if you are confident with basic plumbing and electrical work. Isolate the pump with the valves drain it disconnect the wiring and install a new pump. If unsure call a heating engineer.
How much does a new central heating pump cost?
A replacement pump costs between fifty and one hundred and fifty pounds depending on the make and model. A heating engineer will charge eighty to one hundred and fifty pounds for fitting making the total cost one hundred and thirty to three hundred pounds.
How long do central heating pumps last?
A central heating pump typically lasts ten to fifteen years with proper maintenance. Regular bleeding and keeping the system clean can extend the life of the pump significantly.