How to Fit a Pegler Terrier TRV (UK)
Fit a T31 head onto a UK radiator. Drain, isolate, PTFE, refill and balance.
Pegler
Part
Pegler Terrier — T31 head. Confirm 15 mm or 22 mm tail before ordering.
Drain and remove
Isolate boiler. Drain enough to drop the affected rad — usually 2–3 L per rad below flow level. Undo old valve with two spanners to prevent copper twist.
Fit and balance
4–5 wraps PTFE clockwise on the tail. Nip up the union. Refill, add inhibitor, bleed. Balance by closing the lockshield to give an 11 °C ΔT across the rad at design flow.
Frequently asked questions
- Can I fit a Pegler Terrier on the flow or return?
- Bi-directional TRVs (most modern) fit either way. Legacy uni-directional valves must be on the flow — check the arrow on the body.
- TRV in bedrooms?
- Building Regs Part L requires TRVs on all rads except the room with the room stat.
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