my central heating is a gravity fed condencing boiler.had been still for around 6 monthes. however ! up on restarting have found several problems of which i have cured most. there seems to be the large radiator down stairs thats still not getting hot, the feed pipe its hot but the return pipe is cold.rad only luke warm where as all others are very hot. have replaced the pump! replaced rad valves. checked 3 way actuator valve and re-cleaned that.flushed out rads still need to replace a gate valve to copper tank(hot water) would a power flush help . or is there another problem i have'nt spotted, has any one got any other ideas, unless your a plumber please dont make a comment. contact me at ****.****@ntlworld.com
central heating problem
- Thread starter petewg
- Start date
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it just gets luke warm! i have tried balancing all rads! have switched all but this rad off, have tried opening all rads. but stlll the same. i think the salution is power flush, as i said earlier the flow pipe to rad is hot up to rad! the return pipe is cold, the rad has been removed and flushed out today, with new valves fitted, hence the return pipe might be blocked or narrowed stopping the flow returning in system!! however if you have more ideas it would most certainly help!!
my first thought was a balancing problem, but if you have turned off ALL the other radiators and this one does not get hot, then either the flow is obstructed, or it is bypassing the rad, either through a bypass (is there one, and is it hot?) or through the cylinder (are the cylinder primary pipes getting hot even when they should be turned off?)
I would look next for a seized TRV or closed lockshield. However you say you have changed the valves, so next I would look for a blockage, assuming this is not one of those tall column rads, which have to be installed in a special way as they have internal flow diverters.
Have you disconnected the rad valves from this rad and let them flow into a bucket? Do they both have good flow or does one seem choked? Do you find any sludge or sediment coming out? What colour is it?
What cleaning and inhibiting chemicals have been used? was there evidence of gas or air when you bled the rads? What has happened since it last worked correctly (or did it never?)?
When you say Gravity, do you mean it has a Feed & Expansion tank in the loft? Is it full? Is there mud in it? Are there any signs of pumping over?
I would look next for a seized TRV or closed lockshield. However you say you have changed the valves, so next I would look for a blockage, assuming this is not one of those tall column rads, which have to be installed in a special way as they have internal flow diverters.
Have you disconnected the rad valves from this rad and let them flow into a bucket? Do they both have good flow or does one seem choked? Do you find any sludge or sediment coming out? What colour is it?
What cleaning and inhibiting chemicals have been used? was there evidence of gas or air when you bled the rads? What has happened since it last worked correctly (or did it never?)?
When you say Gravity, do you mean it has a Feed & Expansion tank in the loft? Is it full? Is there mud in it? Are there any signs of pumping over?
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your quote!!
have you disconnected the rad valves from this rad and let them flow into a bucket? Do they both have good flow or does one seem choked? Do you find any sludge or sediment coming out? What colour is it?
This i have'nt tried yet!! thanks i will do this!!
the system has had fx 2-3-4. after removing old pump ,inspection found that lime scale had built up so much it reduced the flow, this makes me beleave your stament that possable returned pipe blocked in this area!!
yes this system has a header tank.
the large rad did have black water and sludge in.but has been removed and flushed out.
summing up!! return pipe problem!! will flush with rad return off next job. then whole system. many thanks to you for advice..
have you disconnected the rad valves from this rad and let them flow into a bucket? Do they both have good flow or does one seem choked? Do you find any sludge or sediment coming out? What colour is it?
This i have'nt tried yet!! thanks i will do this!!
the system has had fx 2-3-4. after removing old pump ,inspection found that lime scale had built up so much it reduced the flow, this makes me beleave your stament that possable returned pipe blocked in this area!!
yes this system has a header tank.
the large rad did have black water and sludge in.but has been removed and flushed out.
summing up!! return pipe problem!! will flush with rad return off next job. then whole system. many thanks to you for advice..
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