Room Thermostats and What They Actually Control
The room thermostat measures air temperature in one location and tells the boiler when to stop and start heating, but its placement and calibration matter as much as its condition.
The room thermostat measures air temperature in one location and tells the boiler when to stop and start heating, but its placement and calibration matter as much as its condition. A perfectly working thermostat in the wrong spot can still make heating feel inconsistent.
What it does
It reads ambient temperature and switches the demand signal to the boiler on or off around a set target, either through a simple switch or, on smart models, a more gradual modulating signal.
How it fails
The internal sensor drifts with age, batteries fail on wireless models, or its position — near a radiator, in direct sun, or in a draught — gives it a reading that doesn't reflect the rest of the house.
Repair or replace
A drifting or unresponsive thermostat is replaced rather than recalibrated in most cases, since modern units are inexpensive relative to the labour of adjusting old mechanical ones.
Questions we get asked
Is thermostat replacement Gas Safe-only work?
No, this is electrical and controls work, not gas work, though we're happy to check it as part of a boiler service.
Can I move my thermostat myself?
Wireless thermostats can often be relocated easily; wired ones need new cabling run, which is more involved.
Are smart thermostats worth fitting?
They offer more control and scheduling flexibility, but a well-placed basic thermostat and a working programmer can heat a home just as effectively.