How to Power Reset a Heat Pump
Step by step UK guide.
A power reset is often the first and simplest step when a heat pump stops working, displays a fault code, or behaves unexpectedly. Done correctly, it can clear temporary software glitches and allow the system to restart normally.
This guide explains when to reset, how to do it safely, and when a reset is not the right solution.
What Is a Heat Pump Power Reset?
A power reset (sometimes called a hard reset or power cycle) involves fully isolating the heat pump from its electrical supply for a short period before restoring power.
This allows:
Control boards to fully shut down
Temporary faults to clear
Sensors and communications to re-initialise
⚠️ A reset does not fix mechanical faults, refrigerant issues, or wiring problems — but it’s a valuable diagnostic step.
When Should You Try a Power Reset?
A power reset is appropriate if:
An error code has appeared after a power cut or storm
The heat pump is unresponsive
Heating or hot water has stopped unexpectedly
The system is stuck in standby or defrost
The controller screen has frozen
If the same error code returns immediately after a reset, further investigation is required.
When You Should Not Reset the Heat Pump
Do not repeatedly reset the system if:
A serious fault code is displayed (compressor, high pressure, refrigerant)
The unit trips the RCD or MCB
You can smell burning or hear unusual mechanical noises
The system is leaking water or refrigerant
Repeated resets can mask faults and potentially cause damage.
How to Power Reset a Heat Pump (Correct Method)
Follow these steps in order.
Step 1: Turn the Heat Pump Off at the Controller
Use the main controller inside the property
Set the system to OFF (not just standby)
Wait 30 seconds
This allows the system to shut down cleanly. If you are unsure how to do this you can skip this step.
Step 2: Isolate the Electrical Supply
You must fully cut power to the heat pump.
This is usually done by:
Turning off the local isolator switch near the outdoor unit, or
Switching off the dedicated MCB/RCD in the consumer unit
✔️ The display should go completely blank
✔️ The outdoor unit should be silent
Some H
Step 3: Wait at Least 5 Minutes
This step is critical.
Control boards contain capacitors that need time to discharge
Some manufacturers recommend 10 minutes
⏱️ Minimum wait time: 5 minutes
Step 4: Restore Power
Turn the isolator or breaker back ON
Wait for the controller to boot up (this can take 1–3 minutes)
Do not press buttons while it starts.
Step 5: Restart from the Controller
Turn the system back ON
Observe the system for:
Normal startup sequence
Error codes returning
Compressor starting after a delay
Most heat pumps include a compressor protection delay — this is normal.
What Should Happen After a Reset?
✔️ Error code cleared
✔️ System resumes heating or hot water
✔️ Outdoor unit starts after a short delay
If the system runs normally for several hours, the issue was likely temporary.
If the Error Code Comes Back
If the same fault returns:
Make a note of the exact error code
Identify the manufacturer and model
Use our error code lookup to find the correct explanation and next steps
👉 Find your heat pump error code
Manufacturer-Specific Reset Differences
Some manufacturers have additional requirements:
Vaillant / Glow-worm – certain faults must be acknowledged on the controller
Daikin / Mitsubishi – outdoor unit isolation is essential
NIBE / Samsung – reset alone may not clear alarm history
Always follow manufacturer guidance where available.
Does a Power Reset Affect Settings?
In most cases:
❌ Heating schedules remain unchanged
❌ Weather compensation stays active
❌ Hot water settings are retained
However, very old systems or systems with flat backup batteries may lose time/date settings.
When to Call an Engineer
Contact a qualified heat pump engineer if:
The fault code persists after reset
The system repeatedly trips electrics
Heating or hot water does not return
You see pressure-related or compressor faults
A reset is a diagnostic step, not a repair.
Related Guides
Quick Summary
A power reset is safe when done correctly
Always isolate power fully
Wait at least 5 minutes
If the fault returns, investigate — don’t keep resetting