Circulating Pumps and Why Radiators Go Cold at the Far End
The circulating pump pushes water round the heating circuit so every radiator gets its share.
The circulating pump pushes water round the heating circuit so every radiator gets its share. A pump that's failing, seized, or set to too low a speed often shows up as radiators that are cold at the far end of the system rather than a boiler that won't fire.
What it does
An electric impeller pump, usually built into or bolted directly onto the boiler, keeps water moving continuously round the sealed heating circuit while there's a demand for heat.
How it fails
Bearings wear and the pump gets noisy, the impeller seizes after standing idle (common after summer), or debris in the system jams it.
Repair or replace
A seized pump can sometimes be freed by manually turning the shaft, a fix worth trying before assuming failure. A worn or electrically faulty pump is replaced rather than repaired.
Get a sluggish heating system checked
Tell us which radiators are cold and where they sit relative to the boiler, and we'll check the pump alongside balancing and any blockages.
Questions we get asked
Is pump work Gas Safe-only?
Where the pump is integral to a gas boiler, yes; a standalone pump elsewhere in the heating circuit is a heating-circuit job rather than gas work.
Can I try freeing a seized pump myself?
Only if you're comfortable isolating power and the system first — otherwise this is best left to an engineer.
Does pump speed matter?
Yes, a pump set too low for the system's resistance leaves distant radiators starved of flow even when the pump itself is working fine.