Tracing Central Heating System leak !

[Monkey Wrench]

A new customer of mine moved into a newly refurbished old stone two storey house a year ago. The house had been completely refurbished but the developers had just removed all the old radiators, done whatever
work was necessary to the walls etc and then replaced and painted the old radiators. None of the original gravity fed CH and hot/cold water system pipework was touched or replaced. After moving in, the customer
found the heating and hot water system to be totally inadequate and so had a new Worcester Greenstar 42CDi combi boiler installed by a local RGI (not me).

The new system was a great improvement but after a few months the customer noticed that the system was losing pressure and had to be topped up regularly (virtually every day). He called the RGI that
had installed the new boiler only to told that he (the customer) should contact Worcester directly about the problem (some customer service from the RGI).

At this point, rather than contact Worcester, the customer called me and, after checking the system (incl boiler & PRV) and finding no leaks I put some fernox leak sealer in the system which cured the problem completely.

However, I have recently replaced 12 of the old radiators with new ones (all pipe modifications have been made above floor/ground level) and yesterday re-filled the system. Got the system up to 1 bar where it held but, an hour
after I had left for the evening, it started to drop quickly and, after several attempts to re-pressurise the system, the customer turned the boiler off. Returned this morning and the upstairs radiators all needed re-filling and I could
not get the system up to pressure at all. The leak is definitely down stairs as there are no signs of water damage to any of the downstairs ceilings.

The problem is that the ground floor is all new tongue and groove wooden flooring laid onto an insulation foam directly onto stone/concrete. To make matters worse, the skirting boards have been installed over the floor edges so
there's no easy of lifting the floor for inspection.

Can anyone please recommend a way of tracing the leak without having to remove the whole floor ? I aware of companies that do thermal imaging but does actually it work ?

Thank you for any helpful advice.

 

[chris watkins]

Sounds like a surface re-pipe required, hope qualified the dangers before installing new rads & pipework.
How quickly is it loosing pressure ??

 

[Monkey Wrench]

Thanks for the post Chris.

Yes, I certainly did advise the potential problems before undertaking the work.

The reason why all pipe mods were done above floor level was to ensure minimum disturbance of existing pipework and to keep all new floor coverings intact. I was extremely careful to ensure that pipe work that I couldn't see (below the floor) was not pulled or stressed in any way.

 

[chris watkins]

How quickly is it loosing pressure Monkey ?

 

[Monkey Wrench]

As much as I tried, I couldn't pressurise the system at all this morning. Considering I had it at 1 bar yesterday afternoon (about 4:30pm) this morning, after opening the filling loop for a over a minute, I still wasn't getting any pressure in the system. I'm going to try again tomorrow and ask the customer to fill while I crawl around downstairs listening for any water leakage although I doubt I'll hear anything. Fortunately, I'm on very good terms with the customer as I had already fully explained the potential problems of both pressurising an "open and very old" system as well the risks in disturbing it.

 

[chris watkins]

As a last resort I would try what you are proposing, it may help if you can get a stethoscope to help pick up sounds of leak.
Best of Luck.

 

[Monkey Wrench]

As a last resort I would try what you are proposing, it may help if you can get a stethoscope to help pick up sounds of leak.
Best of Luck.

Fortunately, my wifes a nurse so I do have access to one !

 

[Destroyer2813]

I have a strange feeling its not recommended to put leak sealer into a worcester boiler but may be proved wrong

 

[chris watkins]

Wish I had access to one ! ----- (nurse that is not stethoscope, Oooooo)

 

[Monkey Wrench]

I have a strange feeling its not recommended to put leak sealer into a worcester boiler but may be proved wrong

I think that's Viessman, not Worcester.

 

[Monkey Wrench]

Wish I had access to one ! ----- (nurse that is not stethoscope, Oooooo)

:cheesy:

 

[Centralheatking]

I would turn all the rads off at both ends, isolate the flow and rtns to the boiler and feed in as much mains water as it will take to show where the leak is - it may do some damage but go 4 it.

there is no real clever alternative.

centralheatking

 

[Resolute]

Would it not be better just to re-pipe? If old pipework is under floor and in a bad condition then you might spend a lot of time tracing and repairing a leak only for another leak to appear a month or two down the line.

 

[buckley plumb]

i would never put a combi on anyold pipework thats in a concrete floor without a disclamer it cant be guaranteed - been to many where others have and had problems. as said if its an external filling loop shut flow and rtn at boiler off and turn filling loop on fully this would find any leaks - listen and look for water damage . could you not lift floor inside a cupbord etc and crawl under floor

 

[Monkey Wrench]

Thank you for the posts. The filing loop is within the boiler and one of those stupid white plastic keys which I hate. Re-piping will mean wripping up all of the wooden flooring on the ground floor which will obviously be a right PITA !

The other option would be to re-pipe on drops from upstairs but, apart from all the pipework having to be run on the surface in trunking, it would also mean pulling up all the new upstairs carpets.

 

[WHPES]

break it down into sections and use pressure test pump. Process of elimination.

Check for encrustations on joints. You may not see moisture as it may be evaporating at the rate it comes out.

 

[tamz]

A leak that size will be easy to find. Get a board up somewhere, stick your head in and listen.

 

[stevetheplumber]

you have checked its not going down the condesate pipe? im suprised you cant here it running

 

[Monkey Wrench]

break it down into sections and use pressure test pump. Process of elimination.

Check for encrustations on joints. You may not see moisture as it may be evaporating at the rate it comes out.

The only visible pipework is at the boiler and radiators, all other groundfloor pipework is in the floor.

A leak that size will be easy to find. Get a board up somewhere, stick your head in and listen.

Unfortunately, there's no boards to pull up as its a solid floor underneath the suspended wooden flooring.

you have checked its not going down the condesate pipe? im suprised you cant here it running

No, it's definitely not going down the condensate pipe.

I'm going back this morning with a stethoscope so will post later how I get on.

 

[Monkey Wrench]

Just a quick update. The leak turned out to be a bad solder joint on a 22/22/15 tee on the main ground floor return to the boiler. I had to take up three layes of flooring (wooden floor, chipboard floor, wood covering ducting) in order to access the leak in an awkward corner of a room. A right b*****d but got there in the end.

However, it now seems as though there's a partial blockage in the downstairs flow/return as the upstairs rad's are hot before the downstairs rad's are still barely warm. Apparently it's always been like this but obviously needs sorting. Shutting off the upstairs rad's get's the downstairs rad's hot within about 15 minutes and the boiler doesn't lock out so it's not too bad but could definitely be improved. I've turned the upstair's radiator lockshields down a couple of turns but it hasn't improved things very much so will try locking them down a bit more. I'm certainly not going to power flush the system (who knows what could happen) so I'll probably end up adding a sludge remover to see if I can improve circulation that way.