UK trade guideRadiator & Heating 4 min readUpdated 9 July 2026

How to Fit a Lockshield Valve (UK)

Install a lockshield radiator valve on the return side. Angled vs straight, 15 mm compression.

PeglerHoneywellDraytonDanfoss

Function

Lockshield sits on the rad return, capped so end-users can't adjust — set once by engineer to balance flow.

Fit

Same procedure as any rad valve. PTFE 6 turns clockwise on tail. Nut and olive on pipe side. Set position with 4 mm hex key — usually 1.5 turns from closed for a mid-house rad.

Frequently asked questions

Where does the lockshield go — flow or return?
Return side always. TRV on flow.
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