I have a radiator in a single room that appears to have a heat difference between input and output of around 27 degrees.(Input 55.9 output 28.1)

Input 55.9 degrees


Output 28.1 degrees


The radiator itself is only measuring about 30 degrees and the room is not heating up significantly.

Other radiators in the house are heating up fine, with a difference between 10-15 degrees of input and output.

The radiator has been bled and does not appear to have any trapped air in it.

What could explain this differential in input and output temperature?

  • 1) Water not flowing well, for any of a number of reasons.. 2) Particularly cold room sucking a lot of heat out of the water as it flows through.
    – keshlam
    Commented Oct 8, 2023 at 15:09

1 Answer 1


Partially closed valve, or an obstruction (well, I suppose a partially closed valve is an obstruction) limiting flow.

That could be anywhere on the pipes serving this radiator or it could be inside the radiator.

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