Oh no, a plumbing Q!
Discussion
Chap came in yesterday to change the bathrooom rad, and of course the system had to be largely drained.
All the rads are now working again except the kitchen one, which is also the drain point. It remains stubbornly cold, even though both pipes to it are hot.
If I try draining some water off from the bottom, hot water just goes straight out of the catflap and leaves the rad cold.
Do I have to bleed a radfull of cold water out of the bleed screw? It will take ages!
All the rads are now working again except the kitchen one, which is also the drain point. It remains stubbornly cold, even though both pipes to it are hot.
If I try draining some water off from the bottom, hot water just goes straight out of the catflap and leaves the rad cold.
Do I have to bleed a radfull of cold water out of the bleed screw? It will take ages!
simpo two said:
Chap came in yesterday to change the bathrooom rad, and of course the system had to be largely drained.
All the rads are now working again except the kitchen one, which is also the drain point. It remains stubbornly cold, even though both pipes to it are hot.
If I try draining some water off from the bottom, hot water just goes straight out of the catflap and leaves the rad cold.
Do I have to bleed a radfull of cold water out of the bleed screw? It will take ages!
Sounds like the rad valves haven't been opened, if there's hot water in the pipes and none in the rad it's not getting into the rad.
sleep envy said:
Chap came in yesterday to change the bathrooom rad, and of course the system had to be largely drained.
All the rads are now working again except the kitchen one, which is also the drain point. It remains stubbornly cold, even though both pipes to it are hot.
If I try draining some water off from the bottom, hot water just goes straight out of the catflap and leaves the rad cold.
Do I have to bleed a radfull of cold water out of the bleed screw? It will take ages!
Sounds like the rad valves haven't been opened, if there's hot water in the pipes and none in the rad it's not getting into the rad.
This is what I was gonna say, I've had this before.
simpo two said:
I thought that if a rad was cold it indicated that it had air in it? Could that be the cause?
Caveat: I know sweet FA about CH systems
Usually, but in this case I'm getting cold water out of the bleed valave, not air, so it must be full.
It could be that the valves are shut, but you mentioned that you opened the valve at the bottom. I hope that this is me being stupid, but you won't get any air out of the bottom. The bleed valves are at the top of the radiator.
dilbert said:
It could be that the valves are shut, but you mentioned that you opened the valve at the bottom. I hope that this is me being stupid, but you won't get any air out of the bottom. The bleed valves are at the top of the radiator.
Drain valve/vent at bottom, bleed valve at top. Both pass water freely.
I don't quite understand how both pipes can be hot and yet you're sure it's full of water - surely the fact the pipes are hot shows that there is some form of circulation through the rad, which would look like an air problem... have you tried both air valves (should be one of each side)?
Try turning off the valves to all the other radiators. This should aid flow through the affected rad and help clear air from the system. When the radiator has warmed up, open the other rad valves. The problem rad should stay warm.
If it doesn't, you may need to 'balance' the system by reducing flow through the other radiators (This is done by closing the valves that you don't normally adjust - at the opposite ends of the radiators to the valves you usually open / close to adjust the heat of the rad)
Let me know if this works - this was the advice given to me by a plumber mate to deal wuth the same problem at my house - I'll be trying it tonight!
If it doesn't, you may need to 'balance' the system by reducing flow through the other radiators (This is done by closing the valves that you don't normally adjust - at the opposite ends of the radiators to the valves you usually open / close to adjust the heat of the rad)
Let me know if this works - this was the advice given to me by a plumber mate to deal wuth the same problem at my house - I'll be trying it tonight!
You don't say if it's a gravity or a pumped system. The thing to look out for is the number of pipes. If you can see a flow and return, i.e. the radiator is "connected in parallel" then you probably have a pumped system. If the actual radiator valves are open (don't forget that thermostatic valves have a mind of their own) it does seem a bit odd.
If it's a single feed gravity system, i.e. both sides of the radiator are connected to the same pipe, then it's not at all uncommon for the radiator to become silted up. The other thing that is very important with a gravity system is that the "spare valve", is properly adjusted.
The spare valve is the one under the protective cap that can't be adjusted without a screwdriver. With a pumped system this valve is often wide open, although that's not ideal, it will work. with a gravity system, that adjustment is critical.
Edited to add;
Don't ask me.... no really. It's me dad that's the heating engineer.
>> Edited by dilbert on Wednesday 30th November 13:15
If it's a single feed gravity system, i.e. both sides of the radiator are connected to the same pipe, then it's not at all uncommon for the radiator to become silted up. The other thing that is very important with a gravity system is that the "spare valve", is properly adjusted.
The spare valve is the one under the protective cap that can't be adjusted without a screwdriver. With a pumped system this valve is often wide open, although that's not ideal, it will work. with a gravity system, that adjustment is critical.
Edited to add;
Don't ask me.... no really. It's me dad that's the heating engineer.
>> Edited by dilbert on Wednesday 30th November 13:15
Thanks all, esp. DarkSide and Dilbert. I eventually found what the problem was...
My kitchen radiator is always left in the 'on' position. When I was playing with the drain and bleed valves I also tried turning the main valve but it was stuck fast - I assumed it had just seized up through lack of use and jammed open.
Anyway, with no other options to try, I eventually got some mole grips and forced the bugger - guess what? It was closed
Plumber man must have closed it and forgot to open it again. Bingo, one rad full of piping hot water 
My kitchen radiator is always left in the 'on' position. When I was playing with the drain and bleed valves I also tried turning the main valve but it was stuck fast - I assumed it had just seized up through lack of use and jammed open.
Anyway, with no other options to try, I eventually got some mole grips and forced the bugger - guess what? It was closed
Plumber man must have closed it and forgot to open it again. Bingo, one rad full of piping hot water Gassing Station | The Pie & Piston Archive | Top of Page | What's New | My Stuff