How do I fix leaks in pipes embedded in concrete floors?

[sryley]

I've got a sealed central heating system that slowly loses pressure over a period of a few days. I need to keep adding water to the system otherwise the pump seizes up and my hot water and heating go off. I've tried Fernox leak fix but no joy. I've got wooden floors and tiles on top of the concrete floors, so identifying where the leak might be is almost impossible, with no evidence of damp as a guide.

How can I go about fixing the leak or who could I get in touch with to help? Local plumbers haven't come up with any bright ideas, just a shrug of the shoulders when they replace my pump yet again.

Thanks in advance,

Simon

[Mike Taylor]

almost certainly it is because your copper pipes were poor quality when fitted and were not protected from the corrosion caused by touching the cement in the concrete. You will have a serious if not impossible job of fixing the leak(s) due to the whole pipe will be affected. All you can do is repleace all the heating pipes where buried in concrete. This may be easier and cheaper to replace all the flow and returns to the rads to a more convenient position without being buried within the floor screed. I.E. all within the 1st floor joists then on drops to each rad. I cannot see how any plumber would be interested in "fixing" the leak as it will go again tomorrow, day after or next week and you will then blame him. Best of luck

[Sparks]

...That's assuming the leak IS in the concrete!

Sparks...

[Andrew Gabriel]

We've had a few threads recently where people can see all the pipework, and still can't find the leak, so being unable to immediately see the leak doesn't imply it's out of sight. Look back over those for some tips.

[andrewpreece]

Check the leak is not in fact water being lost out of the overpressure valve ( should vent outside ) when the system fires up. To test, I'd suggest repressurising the system, and watching the vent outlet when the CH comes on. The underlying problem might then be your expansion vessel, which may have lost its air charge. Just a possibility,

Andy.

[sryley]

Thanks for all the replies. Having found and read the plumbing FAQ it does sound like the problem is with the release valve rather than the pipes. I have used it in the past, and when I tried it again recently it did change the rate at which the pressure was dropping. As sometimes its over as little as 1 day but other times it takes a week or more to drop to zero then that would suggest it wasn't the pipes? (he says hopefully)

I saw the pipes go in and there was plenty of insulation around them before concrete was poured. I was a bit worried as a big tree in the back was chopped down which affected the foundations a bit - doorframes started sticking the following year. I thought that might have affected the pipes, or that I caused a leak when I turned the pressure up past 3 bars once, at the time not knowing how much to turn it up to when it had dropped. Could that have caused a leak or should pipes be able to handle that ok? Does the variable rate of pressure dropping suggest the release valve?

Many thanks,

Simon

[sryley]

Thanks for all the replies. Having found and read the plumbing FAQ it does sound like the problem is with the release valve rather than the pipes. I have used it in the past, and when I tried it again recently it did change the rate at which the pressure was dropping. As sometimes its over as little as 1 day but other times it takes a week or more to drop to zero then that would suggest it wasn't the pipes? (he says hopefully)

I saw the pipes go in and there was plenty of insulation around them before concrete was poured. I was a bit worried as a big tree in the back was chopped down which affected the foundations a bit - doorframes started sticking the following year. I thought that might have affected the pipes, or that I caused a leak when I turned the pressure up past 3 bars once, at the time not knowing how much to turn it up to when it had dropped. Could that have caused a leak or should pipes be able to handle that ok? Does the variable rate of pressure dropping suggest the release valve?

Many thanks,

Simon

[andrewpreece]

I think your CH pipes should handle 3 bar with ease, unless faulty. My over- pressure valve blows at 3 bar. If you pressurise your system and note the pressure, then don't use the CH at all for a while ( difficult perhaps in winter ) the pressure should hold unless there is a leaky pipe ( or radiator ). If the system is venting via the blowoff valve due to overpressure, this should only occur when the system's in use and the water in the CH loop gets hot, expands, and finds it has no expansion vessel to expand into, so causing an overpressure and a blow off. If you can't be done with this method, can you stick a balloon or receptacle over the blowoff vent ( whereever it emerges from your wall, presumably very close to the boiler ) and check and see after a few days, or a pressure loss, whether it has vented any water.

Andy.

[Rick Dipper]

I would look at total replcement of the suspected pipes. It might be work bodging in a bit of hose pipe (run over the floor) to test your theory - but this might just turn into its own leak ridden nightmare.

If you are *REALLY" lucky you might be able to get a new small pipe inside the old pipe, but if you have sharp bends you are stuffed. Even if you do this, you will reduce the flow, possibly so much the heating does not work.

Rick

[Jon]

bodging in a bit of hose pipe (run over the floor) to test your theory - but this might just turn into its own leak ridden

the old pipe, but if you have sharp bends you are stuffed. Even if you do this, you will reduce the flow, possibly so much the

I've come into this thread quite late, and haven't read any of it other than the above. See "How does air get into a pressurised system" below. I've got exactly the same problem. So far I've identified most of the leaks (and fixed them). Some tips: Check all pipes for green staining - if it is there clean it off and see if it comes back. Check the ceilings for barely visible staining Check the door frames for rot where they go into the floor. Keep all your doors shut and go away for the weekend (remembering to top the system up first). The smelly rooms have leaks. Slide a piece of paper under the wooden floor and leave it there for a couiple of hours. If it feels damp when it comes out, then you've a leak somewhere in the room. Check any self bleeding valves Finally, set aside a week in the summer to drop down new pipes and box them in.......

Do you live in Surrey? Jon (whose CH pipes have caused more hassle than his Saniflo clone......)

[mike]

Is there a pressure guage on your system ?? If not it is quite easy to have one fitted, this will tell you when to top up the system and will give you a bit more warning as to the pressure level in your system. see link

you order, ask the salesman, for the fitting that goes with it, depends on where you are going to fit it. 15mm or 22mm I have fitted a few of these on systems without guages and they are great.

Finding leaks are a nightmare, they could be anywhere, I suppose all you have to do is trace all pipework, mark everything that you have inspected so as not to go over it twice, look at where the pipes go into walls , they could be rubbing the wall, sprung a small leak, and empties into a cavity.

hope it helps mike

[mike]

flux, left from the installation and soldering of the pipes, this should be cleaned off before it corrodes the pipes. It takes years to corrode, so its probably not going to be your main problem

mike