How to balance your radiators for even heating
Check the steps below first — if you're not confident, get it fixed safely today.
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Most likely cause & what to check
Balancing adjusts the flow rate to each radiator so hot water is distributed evenly around the system. Radiators closest to the boiler tend to get most of the flow — rooms at the far end of the circuit stay cold.
Every radiator has two valves: a TRV (thermostatic) or wheelhead valve to control temperature, and a lockshield valve (usually hidden under a plastic cap) to control flow rate. Balancing adjusts the lockshield valves.
Start by opening ALL lockshield valves fully: use an adjustable spanner to turn them anticlockwise until they stop. This gives you a baseline.
Turn on the heating with all TRVs set to maximum. Wait 20–30 minutes for the system to reach full temperature.
Identify which radiator heats up first — this is the "easiest" radiator, closest to the boiler. Attach a thermometer clip to the pipework on the flow (inlet) side.
Work around the system, closing each lockshield slightly to reduce flow to the fastest-heating radiators. The target is a 12°C drop between the flow and return pipework on each radiator.
It takes several iterations to get right. Re-check the slowest radiators after adjusting the fastest ones — the system is interconnected and changes one radiator affects others.
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