TRV stuck — radiator won't heat up or won't turn off
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Most likely cause & what to check
A TRV that's stuck closed means the radiator won't heat up. Remove the TRV head (unscrew or unclip it) and look at the pin underneath.
The pin should spring in and out freely. If it's stuck down (pressed in), grip it with pliers and gently pull it up — it may just be seized from lack of use.
Spray a small amount of WD40 around the pin and work it in and out several times.
Refit the TRV head and check the radiator heats up.
If the pin won't free up, or the TRV head itself is faulty, the TRV head can be replaced without draining the system — just unscrew the old head and screw on a new matching one.
TRV heads are universal or brand-specific — check the brand on the body before buying a replacement.
🛠 Tools & materials you may need
Get a vetted local engineer to handle it — no hassle, Gas Safe registered.
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