Zone valve not opening — no heating in one area
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →⚠️ Zone valves contain electrical actuators — isolate the boiler and zone valve wiring before removing the actuator head.
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Most likely cause & what to check
A zone valve (also called a motorised valve) is an electrically operated valve that opens and closes to direct hot water to different circuits — typically upstairs/downstairs, or heating/hot water. If one zone has no heat, a stuck or failed zone valve is often the cause.
Locate the zone valves — they are typically in the airing cupboard, fitted to the pipework. Each valve has a cylindrical actuator (the electrical motor) clipped or screwed onto the valve body.
Check the manual override: most Honeywell and Drayton zone valves have a small lever on the actuator (a white or grey tab) that can be slid to manually open the valve. If sliding the override restores heat to the zone, the valve mechanism is okay but the electrical signal or actuator is faulty.
Check the wiring: confirm the thermostat for that zone is calling for heat (turn it up above room temperature) and the timer is in a heating period. If the thermostat is calling but the valve is not opening, use a multimeter to check that 230V is reaching the actuator terminals.
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Frequently asked questions
How do I know if a zone valve has failed rather than just being stuck?
Remove the zone valve motor head (usually held by a clip or screws). The manual lever on the valve body should move freely when operated by hand — if it does, the valve itself is fine and the motor head is faulty. If the lever is seized, the valve body needs replacement.
Can I use my heating while the zone valve is broken?
Sometimes — if the zone valve has a manual override position (usually a lever on the motor head that holds the valve open), you can operate the system temporarily. This bypasses the automatic control, so the boiler will fire whenever there is a thermostat call — you lose zone control but maintain basic heating.
How much does a zone valve replacement cost?
A replacement zone valve motor head (the most commonly replaced part) costs £30–£70. A complete valve body replacement (needed if the valve seat or body is faulty) costs £50–£120 in parts. Fitting by a Gas Safe engineer typically adds £80–£150 in labour.