Advice needed - central heating issues

vacheron

If the small bore piping runs to all the problematic radiators there may be a manifold buried in the fabric of the house somewhere, often under floorboards. These can easily block with limescale etc. but the guys doing the power flush should have noticed this immediately (providing they were doing the job thoroughly).

Example of what they can often look like after a few decades tucked away!

Dicentra

We had a similar issue where some radiators were cold, the plumber did a power flush for about 4 hours and replaced the pump, solved the problem. Has the pump been replaced?

ThisIsWeird

Hi dryjoy.
Type of boiler? Sealed, pressurised, system with a gauge?
When was the original installation - how old are the pipes and rads?
When you say, "We've bled them many times", what do you mean - that you actually released gas many times, or just tried to no avail?
Where are the 'microbore' rads on the circuit? Could you show us the house layout (say from your sales partics) and add where all the rads are, indicating the faulty ones?
This may have to be a process of elimination; if, for example, turning off all the functioning rads still leaves the problem ones cold, you can effectively rule out it being a 'balancing' issue.
If so, the next step would be to check the valves at each end of a cold rad. Is there a smallish, manageable rad amongst them? If so, closing off both valves and disconnecting them from the rad (obviously carefully draining the rad's contents into a shallow dish - with lots of towels...) should allow you to remove that rad (it just lifts off), and that would almost certainly give you some very clear answers to;
1) is the rad full of sediment?
2) when you open each valve in turn, does water spurt out?
and this would almost certainly get you much closer to the cause. Are you up for trying this?
Powerflushing, whilst important to do, isn't always going to work; if a pipe is actually blocked, then cleaner ain't going to get around it in the first place.
Could you answer some of these Q's, please?

Rdwill

Hi.

I had a similar issue.

1. Turn off all the radiators that are working using the trv.

2. Take the trv off the ones that aren't working and ensure the pin springs up when pushed down.

3. Run the heating (and pump) at full power.

This will mean that the flow in the radiator system is only sent to the non working radiators.

4. Cross fingers and wait for the non working rads to get hot.

It worked for me.

dryjoy

Dicentra said:

We had a similar issue where some radiators were cold, the plumber did a power flush for about 4 hours and replaced the pump, solved the problem. Has the pump been replaced?

Yes it has. I believe the new pump is part of the boiler. 

dryjoy

vacheron said:

If the small bore piping runs to all the problematic radiators there may be a manifold buried in the fabric of the house somewhere, often under floorboards. These can easily block with limescale etc. but the guys doing the power flush should have noticed this immediately (providing they were doing the job thoroughly).

Example of what they can often look like after a few decades tucked away!

It’s possible. If this is the case, is it possible to unblock these without digging it out? Or would it just be a case of having to get in there to unblock or replace?

dryjoy

ThisIsWeird said:

Hi dryjoy.
Type of boiler? Sealed, pressurised, system with a gauge?
When was the original installation - how old are the pipes and rads?
When you say, "We've bled them many times", what do you mean - that you actually released gas many times, or just tried to no avail?
Where are the 'microbore' rads on the circuit? Could you show us the house layout (say from your sales partics) and add where all the rads are, indicating the faulty ones?
This may have to be a process of elimination; if, for example, turning off all the functioning rads still leaves the problem ones cold, you can effectively rule out it being a 'balancing' issue.
If so, the next step would be to check the valves at each end of a cold rad. Is there a smallish, manageable rad amongst them? If so, closing off both valves and disconnecting them from the rad (obviously carefully draining the rad's contents into a shallow dish - with lots of towels...) should allow you to remove that rad (it just lifts off), and that would almost certainly give you some very clear answers to;
1) is the rad full of sediment?
2) when you open each valve in turn, does water spurt out?
and this would almost certainly get you much closer to the cause. Are you up for trying this?
Powerflushing, whilst important to do, isn't always going to work; if a pipe is actually blocked, then cleaner ain't going to get around it in the first place.
Can you answer some of these Q's, please?

Yes it’s a pressurised system with a gauge. The new boiler is a Worcester Greenstar 8000 Life. 

I don’t know how old the original installation is, but we’ve been here 11 years and I’m sure it wasn’t that new then. We did have two new rads put in shortly after we moved here - one of the problematic ones is one of the new ones, the others are not. 

In saying we bled them several times, I meant we have tried bleeding the rads but no air comes out, just water - which usually looks pretty clean and clear. 

If a diagram of the system and locations of the rads/the ones with the microbore would be helpful, I should be able to do that. I might have to get my wife to help me draw a diagram and post back when she’s managed to do that. 

Yes we’d be up for trying taking one of the rads off to see if it’s blocked and/or test the valves etc. we discussed that yesterday and one of the problem ones is small, and it’s in the utility room so would be relatively easy to deal with any mess etc, so I think we’ll give that a go. 

Thanks for your help. 

dryjoy

Rdwill said:

Hi.

I had a similar issue.

1. Turn off all the radiators that are working using the trv.

2. Take the trv off the ones that aren't working and ensure the pin springs up when pushed down.

3. Run the heating (and pump) at full power.

This will mean that the flow in the radiator system is only sent to the non working radiators.

4. Cross fingers and wait for the non working rads to get hot.

It worked for me.

Thanks. Do you mean that once working, you turned the other rads back on, but the TRVs back on the problematic ones and all of them were ok after that? 

daveyjp

OP paid BG to install a new boiler and leave the system working.  They haven't done this so all the OP should  be doing is calling BG and telling them they have failed in their duty to carry out the work they were paid to do.  Messing with the install may not be wise.

My now retired has engineer had been called to many properties with issues and quite often he'd see something had been done incorrectly at install which he fixed within minutes.

Rdwill

Yes. Once I'd forced the water through the unworking ones, I turned the working ones back on and all was good.

So the reason you're doing 'my exercise' is to concentrate the pump on the unworking radiators, so if there is a small blockage the pump concentrating on it may push it though.

If you have two not working, then turn off one of the unworking ones also to 'double' the pump effort on the one you are working on.

Chances are there is just a small piece of crud in the radiator / pipe leading to it, that just needs pushing through.