Room Thermostat Not Calling for Heat
The thermostat display is on and the setpoint is high, but the boiler never starts..
The thermostat display is on and the setpoint is high, but the boiler never starts.
What is actually going on
The thermostat display is on and the setpoint is high, but the boiler never starts.
The realistic causes, in order
Flat batteries or a lost wireless pairing on an RF thermostat A failed relay or receiver, so the demand never reaches the boiler Wiring at the boiler terminal strip disturbed by other work, or a missing link on a switched live
What we test on site
Demand signal measured at the boiler terminals, which proves whether the stat is the problem Receiver pairing and signal strength Whether the programmer and stat are wired to work together correctly
Get a room thermostat that won't call for heat diagnosed properly
Most control faults are a battery, a pairing or a single wire — quick to prove and quick to fix.
Questions we get asked
Is a room thermostat that won't call for heat a controls fault or a boiler fault?
Flat batteries or a lost wireless pairing on an RF thermostat
What normally puts a room thermostat that won't call for heat right?
Most control faults are a battery, a pairing or a single wire — quick to prove and quick to fix.
Is it safe to keep using the system with a room thermostat that won't call for heat?
Rewiring controls incorrectly can leave a boiler running with no safe means of switching off. Control wiring should follow the manufacturer's diagram exactly.