On 15 Dec, 20:00, " wrote:

However pressure testing is widely used by professional plumbers, and
particularly for UFH.

A suitable gauge for dry air testing with a 15mm push fit on it is now
about 30 quid (http://www.screwfix.com/prods/72940/...ools/Plumbing-
Tools/Pressure-Test-Equipment/Monument-Dry-Pressure-Test-Kit).

I use one along with a car tyre footpump. It's not foolproof. I just
had to tackle an inaccessible joint with a very slow drip on it, that
didn't show under air testing. (My one and only poor solder joint in a
thermal store installation). But it will show most problems.

Only a knob tests systems with air. It goes bang if it fails and bits
of metal & plastic may fly around at terminal velocities, i.e., it
will terminate you if you're in the way.

One of the aims of the test is to force any weak joint to fail, then
it is not a good idea, i.e. a system failure under a pressure test is
a sucessful pressure test. . Since many fittings are made by no-name
manufacturers in far eastern sweat shops with no quality control,
putting such fittings under air pressure really is not a good idea.

The HVCA recommendation is to test with water if at all possible. If
pneumatic testing is unavoidable. then the recommendations are
onerous, e.g., evacuate areas under test, no more than 0.5 bar
pressure, tie down hoses, calibrated pressure gauge, board over
windows, etc.. You deviate from these recommendations at your peril
(and you needlessly endanger anyone in the vicinity).

Water testing will show a leak far quicker than air. A competent
plumber would have no qualms in filling a new system with water
because he should be confident that there will be no leaks.

Helium leak detectors are used but only by leak detection
contractors.