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Flow Pipe Hotter Than Radiator on Radiator Furthest From Boiler

Postby Nick56789 » Sun Jan 04, 2015 7:42 pm


The radiator that is furthest from my boiler struggles to heat up to the temperatures of the other radiators. I use an infrared thermometer to measure the temperatures and it is consistently 10 degrees cooler than the others.

The flow pipe is fitted with a two-way TRV. As I type the room thermostat is calling for heat, the boiler is on, the flow pipe on this radiator is 55 degrees Celcius, while the hottest part of the radiator is 44 degrees C. The TRV is set to 5, its highest setting. The lockshield valve is fully open.

Is this symptomatic of a blocked TRV?

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Postby htg engineer » Sun Jan 04, 2015 8:23 pm

No, the TRV controls the temperature of the room not the radiator.

Water will always take the easiest route, the furthest radiator has more restrictions in pipework. Try closing the lockshield valves on all pother radiators then only open them up 2/3 turns. The restricted flow through these will increase the flow to the problem radiator.
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