cold rad.

[Mixter]

I have one rad that has gradual virtualy shut shut down. The rad is clear inside and bleeds freely. the feed side gets as hot as ever but the water just will not circulate thru it. Today we have back-flushed the return pipe from it- which flowed freely. The room has a second rad - which gets HOT! This problem rad is like the next inline.
If the feed to the rad gets as hot as it does....and the return flushes so freely, why the hell wont it circulate? Also, it is by no means 'furthest away' from the boiler (which is only three years old Sealed System, and well up to the job size-wise)...there is one right over in an upstairs corner that gets as hot as you want.

Mick.

 

[twgas]

does the cold rad have a TRV? if so the pin is probably stuck.

 

[bengasman]

All rads are virtually same distance from boiler, there is no first or last.
What do you mean by: back-flushed? Return flowed freely?

 

[Mixter]

does the cold rad have a TRV? if so the pin is probably stuck.

theres no trv on it. and the valves are open....BUT, they dont open as much as i expected, which is 'wide open'. spare ones ive looked at arent much different!

What do you mean by: back-flushed? Return flowed freely?

like ive said, the 'feed' side valve gets hot....so we flushed thru the other side return leg - which showed no sign of blockage. My thinking was that if one side had a blockage in the system, the waters not going to circulate round the rad. This room they are in is an extension, so both rads/pipework have been installed as add ons when it was built. Theyve been in situ a good number of years now - and worked fine until very recently. ill just add that the problem rad was in fact new only last year - so it cant be made up inside.
hope this lot makes sense.

 

[gas4you]

Have you tried back flushing the flow?

Don't assume this is not blocked because the pipe is hot. It may be getting hot so slowly that there is not enough force to circulate through the rad.

Is this microbore pipe or 15mm pipe? Is this rad teed off the other lounge rad or on a seperate drop perhaps?

 

[Mixter]

The bore is 15ml plastic (so im assuming there isnt going to be a lot of heat transfer thru the body of the pipe). The rad has started to operate - not so's you'd take the skin off your hand...but what youd term as very warm. While i take onboard the flushing of the feed side for restrictions, i am wondering if it isnt a combination of things behind the original problem? ....length of pipe run away from where it tee's off (6m??)....valves not opening 'all the way'....double rad....AND a small blockage in the return? - hence the rad has now upped its game considerably.
Thanks for the replies.

 

[twgas]

system probably needs balancing