Does the Pegler Terrier II i-temp suit an open-vented system?

Yes — Pegler TRVs work on both sealed and open-vented UK heating systems up to 110 °C.

Factory calibrated to 20 °C at setting '3' on the Pegler Terrier II i-temp. Re-check with a room thermometer after 24 h.

Should I fit a bypass?

Yes — always fit an ABV or a designated bypass loop to prevent pump dead-heading when all TRVs close.

How to Fit a Pegler Terrier II i-temp TRV (UK)

The valve

The Pegler Terrier II i-temp is a UK-standard 15 mm TRV with a removable sensor head. Confirm the valve body (angled or straight) matches your existing pipework before ordering.

Drain the radiator

Close the lockshield and old TRV. Loosen the radiator union at the tail. Drain 1–2 L into a shallow tray. Fit the Pegler Terrier II i-temp body with new PTFE (10 turns) and torque to 20 Nm.

Fit the head

Push the Pegler Terrier II i-temp head onto the valve pin with the digits facing outward. Rotate to '*' frost setting first to seat the wax element.

Bidirectional flow — the Pegler Terrier II i-temp accepts flow in either direction.
Horizontal head orientation — never mount vertically or wax response is skewed.
Balance the system after fitting all TRVs — set lockshields for 11 °C DT.

Frequently asked questions

Does the Pegler Terrier II i-temp suit an open-vented system?: Yes — Pegler TRVs work on both sealed and open-vented UK heating systems up to 110 °C.
Head calibration?: Factory calibrated to 20 °C at setting '3' on the Pegler Terrier II i-temp. Re-check with a room thermometer after 24 h.
Should I fit a bypass?: Yes — always fit an ABV or a designated bypass loop to prevent pump dead-heading when all TRVs close.