moved radiator - now its not getting hot?

[croz1977]

Hi,

I hate plumbing. I just moved a radiator to the other side of our bedroom. I replaced 15mm copper pipe with speedfit and now the radiator is not getting hot? The inlet pipe is really hot but it doesnt seem to be flowing through the radiator as the outlet pipe is cold.

I noticed when i moved the radiator that it appears to be plumbed as a one pipe system as both the inlet and outlet pipes connect to the same main pipe in the hallway. However it worked before so i just left it as it was. Any ideas???? is it cause the speedfit is too narrow at the inserts? or maybe because it is a one piple system and now the water has to flow an extra 2 metres to get to the radiator?

Croz

 

[carlramsay]

hi , I am not a real plumber, but did plumb my own house. And do dabble
A one pipe system, never seen before normally a flow and return. ?
But one suggestion is do you have a TRV valve? . if the pipe is getting hot up to the valve the pin maybe stuck down. unscrew the head and have a look. I take it you have bleed the rad and the boiler pressure is ok.

 

[moggridgeplumbing]

Urrrrr!

Check that both valves are fully open first, and check if air in rad.

 

[croz1977]

Yeah checked all of that..its defintiely to do with the pipework somehow but I cant understand why

 

[hansthebear]

maybe its not a one pipe system and you have piped it as one

 

[moggridgeplumbing]

Turn off one valve - bleed rad until no air spurts out. Open valve again then repeat with other valve.

It can only be air holding the circulation back.

 

[croz1977]

ive tried all of that...im reasonably experience in plumbing but this has stumped me - hot water is flowing freely with a good pressure from both inlet and outlet valves when disconnected form the radiator. Its a new radiator with new valves. The problem is the pipework configuration does not seem to be letting the water flow through the radiator.

By a one pipe system I mean there is no separate feed and return pipes. There is a 22mm pipe in the hallway and both the outlet and inlet pipes from my radiator connect to this. However it has always been this way and used to work. What I have changed form before is a) from copper 15mm to speedfit 15mm b) the distance from the main pipe to the radiator has increased fomr 1 ft to 10ft.

 

[Boilerman2]

If yours is a TRUE single pipe circuit, the pump will only circulate water around the loop, it will take GRAVITY to circulate hot water around the rad, if your new pipework does not rise continuously towards the rad this could be the reason it no longer works!!

 

[moggridgeplumbing]

If you have piped it up exactly the same, circulation should still not be a problem. The problem is as you have used speedfit, then you will have peaks and troughs in the run which will hold air. If by just opening the bleed valve doesn't clear the 'air lock' then turn the valves off, drain rad, open valves individually into a bucket to force the air out. Reconnect rad and bleed.

Plus what boilerman2 says.

 

[croz1977]

OK...Have just tried that suggestion of switching both valves off etc. I filled a bucket form each pipe, couldnt see any evidence of air and the radiator is still not getting hot now it is back on again! This is dirving me mad....

 

[moggridgeplumbing]

Is the top of the rad getting hot or warm?

 

[croz1977]

OK am thinking it must be the pipework and maybe it was just luck that it used to work! Not sure I have a TRUE one pipe system as the house is from the 70's has a c/h pump. However the pipework looks the diagram below in the below link. Does a spur like this work? now i think about it there would be equal pressure both ends so that would explain why the water is not flowing through the radiator?

Thoughts...?

http://www.gas-news.co.uk/discus/messages/18/2997.jpg

 

[croz1977]

The top is getting luke warm

 

[moggridgeplumbing]

It will eventually circulate but it will be sluggish. Did you fit full bore rad valve, if not they may help.

 

[croz1977]

yeah it is actually getting hotter now after 30 minutes so i suspect you are right. It was probably a bit sluggish before but is now more noticable...what's a full bore rad valve? I just picked up a standard one from wickes

BTW..before i lay a new woooden floor do you think I should I consider re-plumbing this? I dont know what the rest of the house looks like but I suspect this is a huge job thats best avoided unless absoloutely necessary?