2 of 6 radiators not working. Tried everything I can think of.

[Limster]

Hi,

today I’ve taken 3 radiators outside to flush, as 2 were not working and one cold at the bottom, I appeared to wash a lot of black silt from all; However, it hasn’t helped with the 2 not heating at all.
one I feel is the last rad (6) and the other position 4 or 5 but hard to tell which order they start up when not heating up.
As soon as I refitted them and started to bleed I knew the problem remained, as the pressure from both was very low with the lock shields closed and trv (on one) open. Other rad has std tap style valve.
I have considered the trv might be stuck closed but it doesn’t appear to be, with lock shield closed and trv open, opening the bleed valve does bring some warm water to the valve (with pump running), closing the trv stops the water from coming out the bleed valve.
please note, this is with the boiler running, without the pump going the water stops coming out of the bleed valve after about an inch in small cup, unless the lock shield valve is open then it fires out as the other rads do.
all other rads are very hot, I have balanced all rads using a duel temp meter to 11 degrees inlet to outlet.
property is a small bungalow, 10mm piping is used throughout. Pressured boiler system. Third rad I flushed out ‘not heating at the bottom’ is now working properly.

I have tried bleeding with all other valves closed, makes little difference, nor do they heat when other rads closed off. Just little to no pressure from inlet pipes with system pressured.

hoping someone can help with some advise,

 

[ShaunCorbs]

Sounds like you have a blocked pipe as both of them should be the same pressure when everything is off

 

[Limster]

Thanks for the reply. I feared that might be the case but wasn’t sure if airlock could be the culprit, would air still hiss out even with an airlock, the air hardly came out on both.

how do I clear a blocked pipe, does that require power flush?
Thanks again

 

[ShaunCorbs]

Remove the rad and attach a hose pipe to the end of one pipe you should have decent flow let it run for a minute or two

then move to the next pipe if there’s not much flow you could try attaching the other end of the hose pipe and giving it a quick blast 10-15 seconds and then remove the mains end and let it run for a a minute is the flow better ?

 

[Limster]

Understood. Great, something I can try myself. Thank you

 

[Ben-gee]

Careful. Think where the muck will end up if you blast it with mains? Don’t want it in boiler.
Break into pipework (eg pump, boiler..) and push mains from there towards the open pipe so the rubbish is flushed out.

 

[ShaunCorbs]

Shouldn’t get that far and if you drain it / let it run it should all come out the hosepipe

 

[Limster]

Thanks for the advice.
I intend to remove rad, connect hose to inlet and run the fill loop in the hope it clears the pipe, if it appears to be blocked still I will break at boiler/pump and attach the hose to flush it through.
Please reply if I shouldn’t flush using the fill loop. Thanks a lot

 

[Limster]

I will repeat on both sides of each rad

 

[Limster]

Hi all,
Water is dribbling out inlet side so no need for a hose pipe, I cranked the boiler pressure to 2 bar but it didn’t make any difference. Is there any point breaking at the boiler to attach a hose, will I achieve more pressure than what’s coming from the boiler?
im a bit worried about attaching a hose to the inlet and pushing towards the boiler due to debris, but will if you think it’s ok for short while. tried blowing down it but it’s definitely blocked. Any other ideas I could try.

 

[ShaunCorbs]

Is it plastic pipe to the radiator or copper ?

 

[Limster]

It’s copper pipe 10mm. There appears to be plastic L connectors about 200mm away from the rad as the pipes disappear up into the walls. There present in all rads

 

[ShaunCorbs]

I would have a look at them first as normally with plastic they block at inserts eg joint locations

 

[Limster]

They were covered in paint. What I have is copper compression elbows, copper pipe to radiator, looks like plastic piping going into the wall which appears to go up

 

[ShaunCorbs]

I would drain down and strip the elbows poking out of the wall and hope your lucky and find the blockage there

 

[Limster]

Hi Shaun, thanks for all the pointers. I stripped down the elbows and although dirty along with the pipes it wasn’t blocked, I ran a wire up the pipe and got pretty far, it came out dirty but no blockage.
I assume the pipe runs into the loft so that would be my next port of call to check any elbows up there. I’ve rebuilt it now and added some x400, I’m not expecting it unblock the pipe but the whole system is filthy (jet black oil behind the bleed valve when I removed) that I thought it can’t do any harm.