Anyone got an idea how to find this leak?

[Cabinetman]

My local Heritage Centre which I do odd jobs for sometimes has a problem, the building was refurbished about 15 years ago and underfloor polystyrene insulation – lots of it with underfloor water heating running through it, was installed, on top of that there is an oak faced engineered floor. They then built internal stud walls on top of that and all the library bookcases around the walls as well. Not the brightest of things to do!
The heating system has developed a leak – quite a bad one it needs re-pressuring every day.
Anybody any ideas how to find out where the leak may be?
I’m taking my divining rods tomorrow to see if that will help but I’m not overly confident. Ian

 

[Spectric]

They have a big problem, started when they had the refurbishment because of the way things were done. By constantly repressurising the system there is water escaping into the fabric of the building, have you noticed any damp patches? The pipe runs should be continous under the floor, all connections should be above the floor with no joints within the bed. Are you sure the leak is within the floor, the main reason they leak within is because someone has drilled a hole or something similar and most leaks occur within the pump and manifold assembly, or where the pipes enter the manifold. Have you tried isolating each loop to see which one is your potential culprit. Going by the way the refurb was done I would bet that no one actually did a sketch to show the pipe layout within the floor if the leak is there.

 

[Jamesc]

I agree with everything Spectric has put above, just one thought that may help. Have a look on the underfloor heating around the controls or manifold for a company that may have installed the underfloor heating (as opposed to the rest of the plumbing). The companies I deal with all do detailed designs and provide accurate drawings for the system to be installed to. You never know they may still have them on file.

 

[Dee J]

As above. A leak in the underfloor pipework is a worst case scenario and everything else needs checking first. What's the heat source? Heat exchangers in boilers can be a source of loss yet give no direct evidence of a leak. Is there a means of isolating the underfloor loops from the the rest of the system and seeing if the leak remains?

 

[Geoff_S]

Is a central heating leak sealant worth a try? It solved a problem in mine albeit a radiator system.

 

[Richard_C]

Curious timing, it being summer.

Have they been running the system even though its warm weather or has it been losing pressure even when its switched off? Not sure how helpful that is, but it might give you some more clues.

Is it powered by a boiler with an expansion vessel in it like a sealed circuit combi boiler? They can fail and give the same symptoms, my understanding is system starts and warms up, water expands, no capacity in expansion vessel because its "gone flat", pressure relief valve operates, system cools, volume drops, needs to be re pressurised. No leak as such.

I was convinced I had a leak in a combi boiler system, need repressurising every few days, took days of not finding a leak, new expansion vessel cured the symptoms.

 

[Cabinetman]

Thanks everyone that’s great information for us to be going on with, I’m sure they will have the plans but the leak only came to my attention this morning, I was brought in to help with the floor which had risen up in places – I think I know why now! From what I can gather they have been repressuring for a long time but of course it has been shut for months and months in between. I will check the expansion tank angle thank you. Also obviously get a plumber in to the gas boiler etc.
I hadn’t thought about there being a manifold that will be good to find and hopefully we might be able to isolate parts of the system. Anyway thanks all. Ian

 

[jimmy_s]

If its UFH installed in routed polystyrene boards with engineered timber on top the flooring will be cupping like hell where the leak is. If its been leaking for ages then I would think the UFH loops are probably ok. 1st thing I'd check is the expansion vessel. Stick something under the safety valve to see if its lifting when the system heats up - could be the exp vessel lost its charge or the diaphragm gone. Press in Schrader valve on top if you get water its gone if not it may just need pumped back up. If its the UFH then find the manifold and isolate it (should have IV's) and see if the boiler keeps pressure need to turn off any pump serving UFH system. If the system holds pressure then no luck its one of the UFH loops. Shut them off one at a time and find the culprit. you will be able to get a straight fitting to suit the UFH pipe and repair it. Giacomini make a lot of adapters and are worth contacting if stuck.

 

[Valhalla]

I think I've found it!

 

[Bristol_Rob]

https://www.specialistleakdetection...uO7YEnrt4sW1jyV1QBGQfhEZ9uFeq83EaAiDaEALw_wcB

Consider a specialist leak detection company

 

[flh801978]

Try and borrow a flir camera or a infra red camera that will pinpoint your leak whilst the heating is on

 

[Doug B]

Drain down, disconnect both ends of each leg from the manifold one at a time, cap one end after bleeding through with the other end connected to a pressure pump & test it for soundness, I use one of these
https://www.tradecounterdirect.com/...a9kl8-i6dxxdqc6EPEdSGMBTzSJNkk0IaAtf0EALw_wcBDon’t do it with compressed air as it can give false readings if there are joints.

 

[spanner48]

To trace the leak, try filling the system with a fluorescent die [Fluorescein/Uraneine, or Rhodanine]; pressurise; wait for the pressure to drop; then, at night, search with an ultra-violet torch. It will glow brightly.

Messy, but effective.

 

[DiyAddict]

Another common problem on condensing boilers is the reservoir that holds all the crud that hasn't been allowed through the filter. If this reservoir isn't cleaned regularly and gets full of crud, this causes the boiler's pressure relief valve to operate, thus reducing the system pressure. Worth checking if you suspect the boiler hasn't had a regular service.

 

[JAW911]

Worcester-Bosch engineers tell me they use heat-sensing meters which apparently work well. Not sure how they sense the difference between a hot pipe and free-running hot water though? We had a leak after a newly installed combi but you could hear it under the floor fortunately!

 

[Beanwood]

All well informed and sensible ideas above, but if it turns put to be an underfloor leak, how about a good old fashioned listening stick? We're a wood working forum, so could probably turn up something with nice bit of decoration on the ear piece ? 5ft Metal Listening Stick with wooden head
(Perhaps it would work with an earth rod if you're doing it 'on the cheap')

 

[Cabinetman]

All well informed and sensible ideas above, but if it turns put to be an underfloor leak, how about a good old fashioned listening stick? We're a wood working forum, so could probably turn up something with nice bit of decoration on the ear piece ? 5ft Metal Listening Stick with wooden head
(Perhaps it would work with an earth rod if you're doing it 'on the cheap')

Would you be able to hear a drip onto polystyrene?
Found the manifold and Plumber is engaged thank you very much everybody. Will try the plumber out with all your suggestions!
The divining rods found one or two areas, two of us found the same areas, let’s just hope that isn’t where the leak is. But I suppose once we have established which line out of the 12 is leaking it would be easy enough just to decommission that one. Thanks again Ian

 

[Valhalla]

Would it not be best to identify the offending heating loop using some sort of pressure tester? Once the loop has been identified - isolate it so:
a) the rest of the system can still run
b) you're not continually pressurising the system thereby pumping more water into the building structure and potentially causing more damage
c) In the absence of construction drawings - start identifying those areas of the system that no longer work......

 

[Beanwood]

Would you be able to hear a drip onto polystyrene?

It won't be a drip though will it? It would be a constant flow of liquid. Although I take the point - it may be at such a low volume it'd be tricky to hear.

 

[Lons]

There's no easy fix if it is under the floor, there are a number of houses locally with floating chipboard floors over polystyrene insulation laid on concrete and I've come across 2 of those leaks on I managed to fix in a 15mm cold water supply pipe but it was expensive as it meant removal of kitchen cupboards and floor, luckily it was obvious where it was and turned out to be a badly soldered joint, the other was much more serious and I was called in to investigate damp walls in a bedroom of a bungalow, I found all the internal walls bordering the hallway to be very damp up to a good 600mm, I was too busy to undertake the work but it turned out to be an insurance job, they had to move out for 4 months and I believe the total cost was in excess of £50k. All caused by a pinhole in a 15mm mains water pipe feeding the bathroom.