Before You Call an Engineer
If your heat pump has stopped working or isn't heating effectively, there are a number of checks you can make yourself before calling an engineer. Many apparent faults are caused by simple issues with controls, settings, or power supply.
1. Check the Power Supply
Ensure the heat pump is switched on at both the indoor and outdoor units. Check that no circuit breakers have tripped in your consumer unit. Reset any tripped breaker and observe whether it trips again.
2. Check the Thermostat Settings
Ensure your thermostat is set to a temperature above the current room temperature. Check that the system is in heating mode, not cooling mode. If your thermostat has a battery, replace it.
3. Check for Error Codes
Most modern heat pumps display error codes on the controller when a fault occurs. Note any codes displayed and look them up in your manual, or call our helpline for assistance.
4. Frozen Outdoor Unit
A thin frost on the outdoor unit is normal — the defrost cycle removes this automatically. However, a thick build-up of ice covering the entire unit indicates a fault. Do not try to chip the ice away. Call an engineer.
5. Low System Pressure
Check the pressure gauge on your system. If it reads below 1 bar, the system may need repressurising. This should be carried out by a qualified engineer to identify and fix any underlying leak.
6. Blocked Air Filter
Some indoor units have a washable air filter. Check and clean it if dusty. A blocked filter restricts airflow and significantly reduces heating output.
7. Frozen Condensate Pipe
In cold weather, the condensate drain pipe can freeze. This is similar to a boiler condensate freeze. You can thaw it carefully with warm water.
8. Blocked Outdoor Unit
Ensure no leaves, debris, or objects are blocking the outdoor unit's airflow. Clear any obstructions and ensure there is at least 30cm clearance on all sides.
9. Refrigerant Leak
If the system is running but producing little heat, reduced refrigerant charge due to a leak is a common cause. This requires an F-Gas certified engineer to diagnose and repair.
10. Compressor Fault
If the outdoor unit is not running or making unusual noises, the compressor may be faulty. This requires immediate professional attention.
When to Call an Engineer
Call a qualified heat pump engineer if: the system shows persistent error codes, there is ice building up heavily, you can hear grinding or knocking sounds, or the system runs but produces no heat. UK Heat Pump Servicing offers same-day emergency callouts across the UK.
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