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✅ HelpfulBoiler & Heating System
The Circulation Pump
The circulation pump pushes hot water from the boiler around your radiators and back again. Without it, heat simply doesn't move — the boiler fires but nothing warms up.
🔍 Where to find it
On modern combi boilers, the pump is inside the casing. On system and conventional boilers it's often located separately — a cylindrical body on pipework near the boiler, usually with a bleed screw on the front and electrical connections.
⚙️ Signs the pump has seized
Boiler fires normally but no radiators heat up. A strained hum rather than a quiet flow sound. The pump body is warm to the touch but no water is moving.
Pumps often seize after summer inactivity — the impeller locks solid with limescale or corrosion.
🛠 Prevention tip
Run your heating briefly in summer — even 15 minutes in June and July. This keeps the pump impeller moving and prevents corrosion. One of the most effective maintenance habits you can build.
The screwdriver trick: External pumps have a bleed screw on the front. With the power off, a plumber can manually turn the impeller to free it — this works surprisingly often and saves the cost of replacement (£150–£350).
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General guidance only — not a substitute for professional advice. Always consult a qualified engineer if you are unsure. Gas work must only be carried out by a Gas Safe registered engineer. Unvented (pressurised) hot water systems must be worked on by a G3-qualified engineer. We accept no liability for any loss, damage, or injury arising from the use of this information.