Error code 20 showing on my Quantum heater. What is this?

This means the heater cannot sense the room temperature correctly.

If new installation should get the installer back to carry out the below -

Ask the installer to switch off the heater at the supply (or both supplies) and make sure the supplies are dead.

If possible you should check the following items and if they are not correct you should contact your installer prior to raising a ticket for a service call.


      • Have the trips in your consumer unit switched off?  (switch back on if they have)
      • Check that the switches controlling the supplies to your product are on
        • There should be a switch (unfused) for the off peak supply
        • The continuous supply should not be on a plug
      • Are the supply cables different sizes, off peak supply should be on a 2.5mm2 cable
      • Have you set up the user interface (control on the top of the product correctly?
      • Have you registered your product

Ask them to remove the right hand & front cover so they can clearly see the Charge Controller PCB.

Ask them to check the room sensor cable is plugged into the PCB in the socket marked ROOM. See picture -

If the sensor plug was loose or not plugged in, hopefully pushing it back in will resolve the issue. Once covers are on and heater is powered up, the heater should work OK.

If FAULT 20 persists, raise an engineer visit - Take 03/82034/0 Charge Controller (includes room sensor in this part).

Applicable to models: 

QM050RF QM070RF QM100RF QM125RF QM150RF 


Require additional help? Please follow link below

Was this article helpful?

That’s Great!

Thank you for your feedback

Sorry! We couldn't be helpful

Thank you for your feedback

Let us know how can we improve this article!

Select at least one of the reasons
CAPTCHA verification is required.

Feedback sent

We appreciate your effort and will try to fix the article