Thermostatic Radiator Valve Not Working
A room that overheats regardless of the number on the valve, or a radiator that never comes on..
A room that overheats regardless of the number on the valve, or a radiator that never comes on.
What is actually going on
A room that overheats regardless of the number on the valve, or a radiator that never comes on.
The realistic causes, in order
A seized pin under the head, the most common cause by a wide margin A failed wax capsule inside the head that no longer expands with temperature A valve fitted on the wrong side or in a position where it senses radiator heat rather than room air
What we test on site
Pin travel and free movement Head response when warmed and cooled by hand Whether at least one radiator is left without a thermostatic valve as a bypass, as good practice requires
Get a thermostatic radiator valve that won't control diagnosed properly
Heads and inserts are inexpensive; replacing them across the house is a genuinely worthwhile efficiency job.
Questions we get asked
Is a thermostatic radiator valve that won't control a controls fault or a boiler fault?
A seized pin under the head, the most common cause by a wide margin
What normally puts a thermostatic radiator valve that won't control right?
Heads and inserts are inexpensive; replacing them across the house is a genuinely worthwhile efficiency job.
Is it safe to keep using the system with a thermostatic radiator valve that won't control?
At least one radiator, usually in the same room as the room thermostat, should be left uncontrolled so the system always has a heat path.