Cold Radiator, TRV problem ???

9 Dec 2011
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United Kingdom
Hi, I have one raditator that is cold within the central heating system. The other rads are all very hot. The cold rad is the last one, and the pipes going to it from the one before are cold. It seems to go in the rad before the last one hot and return cold ? Im told its a possible problem with the TRV on the last rad which is a tower. That would make sense to me if the pipes coming downt to it were hot. I thought there may have been an air lock in the 2nd to last rad so i opened the filling loop and the drain off point (which is on the last rad) and let the water run through for a while) closed it, toped up the pressure bled all the rads still the same. PPlleaassee help!
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Turn the working rads off and see if the problem one heats up.
Its warming up! Thanks! what now? wait till its fully hot and turn the others on ?
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Are the two "backbone" pipes accessible? (They are the pipes that the rad connections tee off) If so, feel them in the section between the last hot rad and the cold rad. Are they hot warm or what? What are they like immediately before the "good" rad?

Is there a marked difference in temperature (by feel) between the two branch pipes directly connected to each rad? Is the difference similar for all rads?
So far so good all seem to have stayed on! Do you think it will come on with the others next time ? how did that work ?

Thanks again!
Now the others are on the problem one seems to be cooling. Guessing i need to get a plumber out to balance the system after reading other threads ? OR is it something i can do myself?
Try turning all the working ones off at the side opposite the TRVs and then back on half a turn. As it worked with all the others off it sounds like a balancing issue. Turning them almost completely off restricts the flow to them and "forces" it to the one that isn't working.

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