[Help] Flushing a heating system

[Barham's tash]

Resident plumbers of NSC does flushing a heating system actually work?

I’ve got a mixture of old and new plumbing/rads in a 4 bed semi detached house with two rads not working very efficiently and the rest fine. Bleeding the system doesn’t do anything - v limited air comes out and the water that does isn’t muddy/dirty.

So the question is should I go to the expense of having the system flushed and would it make any difference to the performance?

System runs off a combi boiler that has sufficient output to efficiently heat the loft conversion which is further away than the underperforming rads so I don’t think that’s the issue.

Yes I’m aware it’s a 5 minute job etc etc so just want some helpful advice before engaging a plumber around my way and getting taken for a ride!

 

[Bold Seagull]

Are there plumbers on NSC? Who knew.

 

[jackanada]

Well there are other answers possible.
The two rads you are talking about could be at end of a long wiggly run off undersized pipes. Valves could have failed. Hard to make any guesses without seeing.
As an experiment turn all the rads except the two you're talking about right down and see if that gets them toasty.
Could just be a poorly planned installation that needs careful balancing.

 

[Acker79]

Well, first you need to get a really big toilet...

 

[WATFORD zero]

Fancy asking a plumber that question at tea time

 

[Uncle C]

Power flushing, in my mind, is to be avoided as in an old system you are taking a gamble on exposing joints or radiators that might leak.

Having radiators that work at a greater distance from the pump could indicate that the system needs balancing. Check out this possibility by turning off the rads that are working fine and see if the hot water diverts to the cold rads. Let me know what happens.

 

[Wardy's twin]

are the ones that underperform (not sure how you measure that) older ones which might be clogged or might not be as efficient at heat transference...

 

[ConfusedGloryHunter]

Have you tried turning them off and on again?

 

[Mr Bridger]

Try balancing the system.
The 2 x rads in question are they the furthest from the boiler?
If so, shut the lockshield valves ( not TRV's) down on the rads nearest the boiler and then quarter turn back on, so you are slowing the flow down to these rads. Open the lockshields fully on the rads in question.
Check to see if the rads in question get hotter. If an old boiler the pump might not be working as efficiently as it was when installed.
Gradually keep doing this until you have all the rads hot.

 

[Questions]

Does the whole rad feel cool or only at the bottom ?

 

[moggy]

Yep, sounds like a balancing issue as mr bridger has stated

 

[Deleted member 2719]

As we are on the subject of radiators and pipes, we appear to be losing 1.25 bar a day in pressure, 99% sure in ain't the combi.
I have one piece of copper pipe that is about 1.5 metres long that got set in concrete in what was the garage, but it was covered in the foam insulation stuff.


The guy that installed it was old school and I saw him as very thorough in all he did.

So what are the chances that this pipe has corroded in 15 years

My instinct is no chance, but what do the pros think?


I see no leaks in my house anywhere.

 

[Wrong-Direction]

Some good initial advise above ^

Sent from my SM-A326B using Tapatalk

 

[Wrong-Direction]

As we are on the subject of radiators and pipes, we appear to be losing 1.25 bar a day in pressure, 99% sure in ain't the combi.
I have one piece of copper pipe that is about 1.5 metres long that got set in concrete in what was the garage, but it was covered in the foam insulation stuff.


The guy that installed it was old school and I saw him as very thorough in all he did.

So what are the chances that this pipe has corroded in 15 years

My instinct is no chance, but what do the pros think?


I see no leaks in my house anywhere.

Are all the pipes on the surface apart from the bit in the garage?

Sent from my SM-A326B using Tapatalk

 

[Papak]

As we are on the subject of radiators and pipes, we appear to be losing 1.25 bar a day in pressure, 99% sure in ain't the combi.
I have one piece of copper pipe that is about 1.5 metres long that got set in concrete in what was the garage, but it was covered in the foam insulation stuff.


The guy that installed it was old school and I saw him as very thorough in all he did.

So what are the chances that this pipe has corroded in 15 years

My instinct is no chance, but what do the pros think?


I see no leaks in my house anywhere.

What are you setting the system pressure to initially? Mine is at 1 bar cold and rises slightly as the temp increases.

It could be a fault in the boiler e.g. a cracked heat exchanger etc. and the amount of water lost isn't that much and could be unnoticeable depending on where it is.

Do you have a PRV and is it showing signs of water loss?

 

[Mr Bridger]

As we are on the subject of radiators and pipes, we appear to be losing 1.25 bar a day in pressure, 99% sure in ain't the combi.
I have one piece of copper pipe that is about 1.5 metres long that got set in concrete in what was the garage, but it was covered in the foam insulation stuff.


The guy that installed it was old school and I saw him as very thorough in all he did.

So what are the chances that this pipe has corroded in 15 years

My instinct is no chance, but what do the pros think?


I see no leaks in my house anywhere.

I do a lot of leak detection like this, and would say get the boiler checked out first, expansion vessel is the main one.

Would contact your buildings insurance as you should be covered under ‘Trace & Access’
The cover is usually up to £5k, and will cover the tracing and accessing the leak but they won’t cover the actual repair.
They will also cover any water damage, drying costs and any reinstatement costs.

All you will end up paying is any excess on the policy and the actual repair.

 

[Deleted member 2719]

Are all the pipes on the surface apart from the bit in the garage?

Sent from my SM-A326B using Tapatalk

No, we also have pipework under upstairs bathroom, landing and 2 Bedrooms. But there is no staining on the ceilings below.

What are you setting the system pressure to initially? Mine is at 1 bar cold and rises slightly as the temp increases.

It could be a fault in the boiler e.g. a cracked heat exchanger etc. and the amount of water lost isn't that much and could be unnoticeable depending on where it is.

Do you have a PRV and is it showing signs of water loss?

I set it to just short of 2 bar.
I have had PRV replaced a year ago and I have checked the pipe isn't being used by putting a flora marg tub underneath it. Dry as a bone.

I do a lot of leak detection like this, and would say get the boiler checked out first, expansion vessel is the main one.

Would contact your buildings insurance as you should be covered under ‘Trace & Access’
The cover is usually up to £5k, and will cover the tracing and accessing the leak but they won’t cover the actual repair.
They will also cover any water damage, drying costs and any reinstatement costs.

All you will end up paying is any excess on the policy and the actual repair.

We had a external expansion vessel fitted last year and it doesn't appear to be leaking.
I hadn't realised I might have cover for this I will check it out thanks.

So is it unlikely to have corroded under the concrete then?

 

[Barham's tash]

Too any to quote easily from my phone but thanks to you all for taking the time with sensible replies.

Balancing sounds the best initial course of action - will try that tomorrow.

To answer some specific questions:

[MENTION=5306]Questions[/MENTION] yes both rads feel cold at the bottom and def warmer at the top
[MENTION=1225]Wardy[/MENTION]’s twin underperforming simply by comparable rooms in same house with same rads working/heating the room fine. All rads bar two in the house (in our 2 yr old loft extension) are probably about 15/20 years old so no discernible difference in my head that would explain the differences in the rooms in question.

 

[BN9 BHA]

Resident plumbers of NSC does flushing a heating system actually work?

I’ve got a mixture of old and new plumbing/rads in a 4 bed semi detached house with two rads not working very efficiently and the rest fine. Bleeding the system doesn’t do anything - v limited air comes out and the water that does isn’t muddy/dirty.

So the question is should I go to the expense of having the system flushed and would it make any difference to the performance?

System runs off a combi boiler that has sufficient output to efficiently heat the loft conversion which is further away than the underperforming rads so I don’t think that’s the issue.

Yes I’m aware it’s a 5 minute job etc etc so just want some helpful advice before engaging a plumber around my way and getting taken for a ride!

The rads that are not working-
Have they got thermostatic radiator valves?
Are the radiators on the ground floor with surface pipes feeding them?

 

[Mr Bridger]

No, we also have pipework under upstairs bathroom, landing and 2 Bedrooms. But there is no staining on the ceilings below.


I set it to just short of 2 bar.
I have had PRV replaced a year ago and I have checked the pipe isn't being used by putting a flora marg tub underneath it. Dry as a bone.



We had a external expansion vessel fitted last year and it doesn't appear to be leaking.
I hadn't realised I might have cover for this I will check it out thanks.

So is it unlikely to have corroded under the concrete then?

The expansion vessel won’t be leaking as such, it will be the diaphragm inside the expansion that splits. Your plumber will be able to check this by opening the Schrader valve and testing to see if there’s water in there.
Regards the pipe under the floor, if it’s protected it should be ok, it’s when it’s unprotected the cement in the screed attacks the copper and pinholes it. How long has the copper been in the floor?
You can sometimes detect a leak on a heating system with a thermal camera, if you haven’t got one, order one, have a look, then send it back to get your money back.