Thermostatic Radiator Valves (TRVs) Explained
A TRV lets you set an individual radiator's temperature rather than relying only on the room thermostat, using a wax or liquid-filled sensing head that expands and contracts with room temperature.
A TRV lets you set an individual radiator's temperature rather than relying only on the room thermostat, using a wax or liquid-filled sensing head that expands and contracts with room temperature. Stuck TRVs are one of the most common reasons a single radiator won't heat up.
What it does
The head senses air temperature and pushes a pin in the valve body open or closed, restricting flow through that radiator as the room approaches the set temperature.
How it fails
The pin seizes in one position, most often stuck closed after standing unused over summer, or the head's internal mechanism wears and stops responding to temperature.
Repair or replace
A seized pin can often be freed by hand or with pliers on the exposed shaft — worth trying before condemning the valve. A worn head or damaged body is replaced.
Fix a stuck or unresponsive radiator
Tell us which radiator is affected and whether it's stuck hot or cold, and we'll check the valve and pin before assuming a bigger fault.
Questions we get asked
Can I free a stuck TRV myself?
Gently working the exposed pin with fingers or pliers, with the system off, is something many people manage themselves; if it won't budge, that's when to call us.
Do all radiators need a TRV?
Not the one in the same room as the main room thermostat, which is usually left as a fixed valve so the two controls don't fight each other.
Is TRV replacement Gas Safe-only work?
No, this is a plumbing and heating-circuit task rather than gas work.