leak in heating system

Hi,

We have had a suspected leak for about 2 years in our heating system. Seemed to lose pressure once or twice a week, wasn't a problem just topped up when needed.

In the past month this has got a lot worse and now lose pressure within hours. Seems to lose pressure when heating turns off.

We have a circa 1870 victorian, no foundations to speak of really just two foot of space below floorboards. No sign of a leak from upstairs i.e. no dampness anywhere visible.

So far any plumber we have talked to runs a mile. We called leakfinders and the guy was helpful but not very hopeful Their system of finding leaks seems to rely on the fact that most pipes are embedded in concrete and they listen for resonances while putting high pressure in pipes. This is unlikely to work in our case.

So short of pulling up our nice oak wood floors, which are glued, we are not sure how to proceed. Any advice would be much appreciated.

Thank you.

First would be to check the usual suspects. Safety valve discharging, automatic air vents weeping, radiator valve glands weeping, low pressure or split expansion vessel diaphragm.

If that does not show up anything, I usually have the system as hot as possible, then use thermal image camera to try & source the leak. This can prove very precise but only sometimes. It really depends on where the leak is.
If that does not work, then the system should be isolated into sectors & pressure tested with compressed air. This does not have to be done at high pressure, it is just to determine the section of pipework that the leak exists in, narrowing down the area. I would also use snake head camera to search under floor boards but not having to lift them/or sections of flooring.

Thanks Shane for your detailed reply, much appreciated.

You could have a leak in your coil in the hot water cylinder.

Thanks burmo.

We did try to isolate it but found it lost pressure regardless of whether the hot water was on or not. Could it still be the coil?