Pipe from oil tank to boiler is leaking somewhere under a few feet of industrial strength concrete

[john.smith1979]

The pipe that goes between the oil tank and the boiler (in my Aunts house) is leaking. Well, no oil is getting through to the boiler and oil is leaking from the pipe close to the tank. The plumber who has looked at it says that the copper pipe is encased in a plastic sheath beneath the concrete and the oil is leaking through the copper and flowing back between the copper and plastic and emerging from the pipe near the oil tank. Is this likely or possible? (I haven't actually seen it myself so i'm only relaying a secondhand account).

The tank is situated about 10 or 15 yards from the house in a secluded spot and ideally she doesn't want to have to move the tank adjacent to the house as it would be unsightly.

How difficult would it be to cut a groove in the concrete with some sort of grinder and relay it? How deep would it have to go as cutting through 2/3 feet of concrete sounds unrealistic?

[Michael Chare]

That is a bit surprising. I would look for obvious damage to the pipe, and investigate whether there is no some other cause of a blockage, such as filter that needs changing.

There is a leaflet on the Oftec web site that says that the pipes should be

450 mm deep.

[Dave Liquorice]

There is oil in the tank? Don't rely on a remote electronic gauge and remember the sight tube will need it's valve opening at the bottom (push button or a small tap) to read correctly. Failing that dip the tank.

Water in a low point of the feed that has frozen. Blocked fire valve. Blocked filter.

Why a "plumber" and not a OFTEC registered heating engineer?

Well it's possible but not likely IMHO. As others has said what would cause the failure? Has the pipe route been driven over by a heavy vehicle recently? Have there been really hard prolonged frosts? I'm thinking of heave due to the ground freezing but the pipe would have to be quite shallow.

The regulation depth of the pipe is 18" but I wouldn't expect anything like that depth of concrete. See if you can prove where the oil is coming from as others have suggested and go from there.