Number of cold radiators

[Deryck Tintagel]

I have a repeated problem with cold radiators. I had a local company to look at the system a couple of years ago which seemed to sort he problem for a while but we are back to cold radiators again.

I have a conventional boiler / HW tank system. All piping is plastic and I think that there may be a manifold under the en-suite floor just above the boiler.

The main problem is the bathroom, hall and downstairs loo radiators. The bathroom and hall are stone cold, and the loo is warm but not too hot. These three radiators are close together - bathroom is above the loo and the loo is pretty much back to back with the hall.

The en-suite radiator is warm, but again not too hot and is directly above the boiler. Other radiators seem OK.

Is the system unbalanced or could there be a blockage somewhere causing the issues? If unbalanced would I shut off all radiators (bar the hall) to see what effect that has and then adjust the lockshields in turn. I am not sure which might the last on the ciruit

 

[denso13]

Turn off all of the radiators and turn on only the problem ones, one at a time. Just to check if they heat up.

 

[Harry Bloomfield]

Is the system unbalanced or could there be a blockage somewhere causing the issues?

It could be either problem, or an airlock..

If unbalanced would I shut off all radiators (bar the hall) to see what effect that has and then adjust the lockshields in turn. I am not sure which might the last on the ciruit

Yes, closing down the valves on the first radiators to get hot, will increase the flow to areas where it doesn't. There is a complex procedure, to fully balance a system.

 

[Deryck Tintagel]

Turn off all of the radiators and turn on only the problem ones, one at a time. Just to check if they heat up.

I have just ried all radiators off except hall, bathroom and loo. The boiler runs for a while and then stops. I assume some sort of overheat?

I have lost my bleed key so will have to grab one on my travels, but I did manage to release two of the bleed nipples with a screwdriver. Just get a dribble of water

 

[denso13]

I have just ried all radiators off except hall, bathroom and loo. The boiler runs for a while and then stops. I assume some sort of overheat?

If they still don't heat then it isn't a balancing issue. Probably pipework/valve blockage. Did they ever work?

 

[Harry Bloomfield]

I have just ried all radiators off except hall, bathroom and loo. The boiler runs for a while and then stops. I assume some sort of overheat?

That suggests no flow through the boiler, it could be the pump, or...

I have lost my bleed key so will have to grab one on my travels, but I did manage to release two of the bleed nipples with a screwdriver. Just get a dribble of water

That needs more investigation, but points to blocked pipework.

 

[accelerator]

Could be a blockage, could just be a balancing issue. With a manifold, it may be the case that the system has been designed poorly so it's relatively difficult for water to flow to some of the radiators.

I would agree with above that a blockage is the most likely.

Have you been using inhibitor in the system?

 

[Deryck Tintagel]

If they still don't heat then it isn't a balancing issue. Probably pipework/valve blockage. Did they ever work?

Yes, they worked then I had the plumbers look at it and they seemed to clear a blockage in the hall radiator. I suspect a blockage as the loo radiator used to be much hotter

 

[Deryck Tintagel]

Could be a blockage, could just be a balancing issue. With a manifold, it may be the case that the system has been designed poorly so it's relatively difficult for water to flow to some of the radiators.

I would agree with above that a blockage is the most likely.

Have you been using inhibitor in the system?

I am guessing at a manifold due to the warmth of the floor in the en-suite although ot could be just the 22mm pipes and joins in that area.

I have not put inhibitor in but I did have some that they put in when they changed a few radiators for me. That said they had problems then so they may have lost much of it in their fiddling

What's the way forward on a blockage? Power flush?

 

[accelerator]

What's the way forward on a blockage? Power flush?

I'm not a huge fan of the power flush, as it's expensive and won't necessarily work.

Personally, before I did anything I would try fiddling around with the lockshield and flow valves in various combinations, to see if there was any way I could get heat into the radiators.

After that, I might take off the radiators and flush them out, and add some inhibitor into the system.

 

[Deryck Tintagel]

Some years ago I had the same problem and had the hall radiator off and opened one lockshield. That seemed to clear the lack of heat for a while. Might be worth another go

 

[denso13]

You could disconnect a problem one and run water through the valves into a bucket to check they are opening ok. Just a case of systematically checking things, to rule in, or out, possible causes.

 

[Deryck Tintagel]

You could disconnect a problem one and run water through the valves into a bucket to check they are opening ok. Just a case of systematically checking things, to rule in, or out, possible causes.

I think that is what I did last time. Job for the weekend

 

[Deryck Tintagel]

Well, just an update and request for thoughts.

I had a plumbing company out yesterday to flush the system. I requested a quote for a power flush but the guys doing it did a Magnacleanse flush - not what I was expecting. They did get some sludge and metallic debris out and I saw bits passing trhough the clear filter pipes. I suspect there was not inhibitor in the system following the last plumber to work on the system, although I cannot be sure.

Rads seemed OK last night but I turned the heating off as it had been running all day and the house was like a sauna! This morning the heating came on but the problem with a cold lounge rad is back and two others that were cold are just warm. The loo which is close to the warm rads, however, is hot. So a partial success.We now have a magnetic filer on the system so I am hoping that might collect more debris from the water.

I suspect that debris has now migrated and blocked a pipe or two. I will try forcing the water around the poor rads to see if that helps. Would an actual power flush do any good at this point, or would it be better to lift the floor in certain areas to locate the potentially blocked pipes ?

 

[denso13]

Would an actual power flush do any good at this point

Possibly yes, if done correctly, but there would be no guarantees.

would it be better to lift the floor in certain areas to locate the potentially blocked pipes ?

Depends on how easy access is and length of pipework etc, you'd be mostly guessing where the problem is. Are the problem ones far from the main/good pipework? Can you DIY some re-piping?