BoilerFaultCodesTechnical description
Contact thermostat has been activated (under floor systems)
What causes this fault?
This fault occurs when an external safety sensor detects that the water flowing into your underfloor heating pipes has exceeded a safe temperature. It is usually triggered by a failure in the mixing valve or the underfloor pump, which prevents the hot boiler water from being cooled down properly before entering the floor. This safety measure is essential to prevent high temperatures from damaging your flooring or the pipes underneath.
This issue is most common during the first cold spells of autumn/winter when underfloor heating systems are turned on for the first time after being idle all summer.
DIY fix possible
Wait for the system to cool down naturally for 30-60 minutes.Check that the underfloor heating pump is running and hasn't seized.Ensure the mixing valve for the underfloor heating is not set too high.