Stud Finder to find metal pipe under concrete floor?

Malpaisian

Hello,

I have a gas CH boiler losing pressure at the rate of 1.5 bar over 10 hours. No leaks above ground. Came to the conclusion that there is a leak somewhere under the ground floor. I pulled up the laminate flooring in the living room, exposing the bare concrete. Floor needed replacing anyway. This revealed a damp patch in one corner of the room (no radiator at this site). I have a thermal imaging thermometer coming tomorrow so that I can ascertain whether this is the leak site or some kind of rising damp problem or damp coming through an external wall.

I suspect there may be a gas pipe running through this area also. I don't think the thermal imager will pick up a gas pipe as it wont give off a heat signature.I don't want to go drilling and digging around in there without first ascertaining where the gas pipe is. I tried using a stud finder today but it won't calibrate when I put it to the concrete floor. Normally you put it to a wall, press and hold a button and the unit produces a continuous tone / beep for a few seconds until it is calibrated. When it stops producing this beep, that tells you that it's calibrated. When I put it to the concrete floor and press the button to calibrate it, the beep does not stop and unit won't calibrate. Works fine on walls though.

Does anyone know if these standard DIY store-bought stud finders are supposed to be able to work with concrete?

antoinolachtnai

I would not expect that type of stud finder to work for your situation but I don't know. There are other more specialised tools you could use.

If you do find that the leak is from the central heating, I think you could consider just running new pipes to your radiators along the walls behind skirting (or relocating them so they are easier to reach with piping). Digging up the floor will be pretty dirty and you may find that the pipe leaks somewhere else underground in a couple of years.

monseiur

It depends on the build up of your floor. Assuming it's screed over insulation, you can easily dig out the damp section area by hand (cold chisel and lump hammer) It's best to remove an area greater than the damp patch in floor for easier access to pipes etc.
Any pipes will be in or under the insulation, non should be in the screed itself. Cut away some of the underfloor insulation and remove the pipe insulation and check for leaks. A leak may not be obvious at first glance/feel, wrap pipes individually with tissue paper and check daily for up to a week as it may be a tiny pin hole leak and it will eventually show on tissue paper.
You may have a more serious leak elsewhere in the house judging by the pressure drop in the system.

Dtp1979

Wo, wo, wo. Dude, chances are, your cylinder coil is leaking.