Removed/rehung rad - now its cold

[gareth1]

Removed a rad for decorating.

When I re-hung it and opened the valves both ends, it bled fine, filled up completely and was hot (heating was on when i re-hung it).

However once it cooled down it did not heat up again next time the heating was on and it will no longer re-heat.

The pipe one end becomes hot, but the pipe the other end and the rad itself remains cold. Both valves are open fully, and if I bleed no air just water comes out.
It is the furtherst from the boiler but I left the heating on for a few hours and it still didn't seem to want to warm.

Is it likely the valve has gone one end ??? Or anyone got any other ideas ?

Thanks
- Gareth

 

[masona]

Have you got TRV on the radiator?

 

[MANDATE]

sounds as though there is some blockage at or near the cold end.
Having removed the radiator I'm thinking you may have dislodged some sludge which is now causing the blockage.
What if you try bleeding the radiator again, but instead of having both valves open close the one at the hot end. This will mean you will get no water out if the cold end is blocked.
Did you flush out the radiator when you had it off?

 

[gareth1]

The Valves aren't thermostatic.

But yes I did flush it through when I rehung it. Stood it on each end angled over the outside drain and blasted a hosepipe down it for a few minutes till the water ran as clear as I could get it.

I'd actually removed two rads in the room and last night I noticed the other one doesnt feel as warm as should be either, although its not as bad as the stone cold one (again seeems to be fully bled).

I'll try bleeding it tonight with alternate valves shut and see what happens.

Cheers,

 

[gareth1]

OK... Bled the radiator with alternate valves closed. To my surprise both times it bled - indicating both valves flowing ok.

Scratch my head. Start pondering... was this radiator ever warm as we only moved in 1 year ago. Ask wife... Yes she replies it used to be fine.

Ponder further. We were away on holiday late Sep - early Oct so only just turned the Central Heating properly in mid Oct, the same time we took the radiators off to decorate. Coincidental I wonder ?

Are you sure you havent played with any of the valves anywhere in the house I ask.....? No she replies... Well, except..... over summer the upstairs radiators used to get a bit warm when the hot water was on..... so i turned all the upstairs ones off for the summer.... but ive turned them all back on.....


A quick check reveals all the upstairs radiators on at full - both ends.
Turned 3 of them off and surprise surprise the cold one downstairs warms up a treat...

Moral of the tale....? Ask the wife first !

I guess now I need a crash course in balancing... Assumedly I turn all rads in the house on full, work out which are the hottest and coldest and then start turning the hotter ones down bit by bit until the cool ones warm up ???

Cheers

 

[MANDATE]

The radiator that switches the room stat acts as a datum and controls the pump, so when this one receives hot water so do all the rest and if it is satisfied and receives no hot water then neither do the others.
On the assumption the system has been fuctioning OK I would leave the lockshield valve on this master radiator at its prestent setting while you make any adjustments to the others.
If you find any room too cold because the radiator does not get hot then you can close the master radiator lockshield valve slightly, this restricts the flow slightly and gives more flow to the remainder, now the others can also be turned down slightly except the cool one.
Well thats how I see it!
also see www.diyfixit.co.uk

 

[gareth1]

OK I'm pretty much there - all seems to be going fine now, just a few more tweaks and im there.

Thanks for your help.