Cold Radiators Conundrum

25 Apr 2009
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United Kingdom
Hi All,

With the arrival of the cold weather we've just fired up the heating in the old house we moved into in the summer, but there's a problem - most of the radiators upstairs don't get warm at all. Here are some hopefully relevant points:

- all the radiators have TRVs
- 7 radiators downstairs, all get hot
- 6 radiators upstairs, only 2 get hot the others are stone cold
- pipes leading to the cold radiators get warm
- I've bled all the radiators
- I've checked that both valves are open on the cold radiators
- turning off all of the radiators except one cold one still doesn't make it get hot

I'd be grateful for any tips on what I can investigate next!

Thanks a lot,
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Adam are you sure the rads are turned on?
Do the upstairs rads have thermostatic valves?
If so try taking the heads off by unscrewing the metal collar. Push the pins in and out with the flat of a spanner.
Give the side of the valve a sharp tap or if you are really brave put a towel on the floor around the valve then try to ease the pin out gently with a pair of pliers till you get some flow.
Be careful the pin may come all the way out and you will have to push it back in.
Thanks, I think you're right. I tried closing the return valve on one of the cold radiators and the water stopped coming out of the bleed valve, which suggests to me that the TRV is jammed.

However, I can't work out how to take off the head of the Danfoss TRV. Other posts about fixing TRVs suggest it should be straightforward, but I can't seem to find any easily moveable collar on this one:

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Fantastic :) I loosened the screw and the TRV head came off easily. After a bit of fiddling/tapping of the pin it freed up and the radiator started working. The same for all the other cold ones :D

Thanks past3bar and kev!


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