Central Heating

[davidk65]

Whilst visiting my daughter, I found that all the radiators are hot (very), but one radiator in hall on the ground floor is stone cold.The house has four bed rooms.
On checking I found that both valves on the radiator had been turned off. I opened them fully and bled the radiator. At first there was a lot of air which eventually stopped and cold water flowed from the bleed nipple. I kept repeating this process and warm/hot water started to flow.The radiator warmed up but not to the same degree as the other radiators in the house. About an hour later, heating still, on the radiator started to cool. Each time I bled the radiator, no air came out, the radiator heated up as before only to cool off again
Any suggestions?

[The Builder]

Possibly sludge settlement David, through lack of use (no water circulating), or, if one valve is aThermostatic Rad Valve ................. they can get stuck, again due to lack of use. Unscrew the control head and take it off (water doesn't come out of here) .......... then look at the little "pin" on the valve body ............ it should spring up into action (to open up the flow)

[davidk65]

Thank you for the quick response.
The valves on the rad are not thermostatic.
It seems reasonable to assume, like you suggest, the rad is blocked. Since reading the reply, I have checked and it is only the top of the rad that is getting hot, almost in a straight line across the width of the radiator . A high percentage of the bottom of the rad remains cold.
When I bleed the radiator, the top gets hot and the connections to both valves the also heat up. Would this indicate that the valves are OK and the problem is the radiator?
If it is; I guess I will need to remove the rad and flush it through?
Thanks again.

[The Builder]

Certainly worth a shot David. If there is a build-up in there, it would be reassuring to know that it wasn't finding its way around the rest of the system.

[terence7556]

take the rad off the wall, take it into the garden and flush it out with a hosepipe

[davidk65]

Have removed the rad and flushed as suggested. Lots of black muck came out kept flushing until it ran clear. Refitted rad and all appeared to be well However, although the rad is warmer than previously it does not reach the surface temperature of the other rads on the system. Can anybody suggest what might be wrong?
I wondered if it is a problem of the radiators not being balanced i.e. the other rads are taking all the heat? If it is, what is correct procedure for balancing?

Thank you.
David.

[The Builder]

............. simple enough job David .......... just takes a bit of explaining ...... this link should save me a bit of typing.
"Pukka" balancing makes use of rad thermometers ........... this link is easier.........

http://www.lovekin.net/radiator-balancing.html

[AlBags]

18C temp drop across inlet and outlet .. you can judge by hand with a little experience.
Use the lockshield valves to damp down all the rads starting with the nearest to pump first .. to achieve the approximate drop.
You need to run that rad for a while .. as you may have some crusty sediment restricting the inlet/outlet valve.

[davidk65]

Thank you again for advice.
Followed the link to the site recommended, gives all that I want.

Thanks.

David