[Help] Flushing a heating system

[Deleted member 2719]

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.

I will check out valve, what pressure should this diaphragmm be set to?

The pipe was put in grey pipe insulation and sunk into the concreate 15 years ago.

Divining rods won't work then.

 

[Barham's tash]

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

Yes to TRVs and no they’re on first floor with pipework beneath floorboards

 

[BN9 BHA]

Yes to TRVs and no they’re on first floor with pipework beneath floorboards

Some good replies on page 1 about balancing, worth a try but I’ve known thermostatic radiator valves to stick and not work, especially if they are old.
I would try what [MENTION=2393]Uncle C[/MENTION] post#6 has mentioned in his last sentence, if the rads work the valves will be ok but you will have to balance the system.

There is a way of cleaning the system with chemicals rather than power flushing with a machine.

 

[Rowdey]

Some good replies on page 1 about balancing, worth a try but I’ve known thermostatic radiator valves to stick and not work, especially if they are old.
I would try what [MENTION=2393]Uncle C[/MENTION] post#6 has mentioned in his last sentence, if the rads work the valves will be ok but you will have to balance the system.

There is a way of cleaning the system with chemicals rather than power flushing with a machine.

This - set TRV to max, and take the TRV head off. Little bit of wd40 on the pin, and press/release on the pin.. make sure it's moving (only a few mm).

 

[Questions]

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.

I’d go sludge in those pair then. Whip them off and have a look. It’ll be apparent straight away… If the system brings in air then there is your probable cause…….. but ‘whip em out ‘

 

[Gotsmanov]

I'd throw money at the problem, and buy a new house.

Hope that helps.

Sent from my GM1913 using Tapatalk

 

[Justice]

So does power flushing work or not? Like getting blood out of a stone asking plumbers a question

 

[Barham's tash]

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.

Thanks, this indeed has worked perfectly.

 

[Mr Bridger]

Thanks, this indeed has worked perfectly.

Great stuff

 

[Arthritic Toe]

...
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.

Ah there's your problem. Try an Anchor butter tub.

 

[Deleted member 2719]

Ah there's your problem. Try an Anchor butter tub.

Haha, I may actually go for some Country Life, squire.

https://youtu.be/7mSE-Iy_tFY

 

[BN9 BHA]

Thanks, this indeed has worked perfectly.

Great stuff

It’s good to see that a problem has been solved by advice given on here.