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(Andrew Gabriel) wrote in message ...

Dry is best for checking for leaks in the system -- it doesn't
damage anything, air leaks much faster that water (even at much
lower pressure) so it is easy to find using gas leak detector spray,
and the pipework isn't wet if you do need to resolder a joint.
Also, you can easily test small completed sections as you go, so
you can reinstate flooring etc having tested the inaccessible
pipework beforehand even if it will be some time before you are
in a position to complete all the pipework and fill with water.

You should test the pressure relief system wet -- I think that
was specified as part of the boiler commissioning procedure in
the manuals for several of the boilers I looked at.

I've noticed Screwfix sell a "dry pressure test gauge" with a Shrader
valve.
Obviously this will only allow to test using pressurised air.

I've noticed some posts on the newsgroup about the dangers of dry
pressure testing.

I think I posted a warning once about the amount of energy you
end up storing when dry pressure testing. Do it in small sections
as you go, one or two radiators at a time. When all the pipework
is finished, you can shut off the radiator valves so they are not
included for the final test, significantly reducing the stored
energy, as you already tested them and their attached pipework.

Thanks for the info.

I am thinking of doing a wet pressure test, and I was thinking of
using the "dry pressure test gauge" to measure the pressure by pumping
air into the wet system - I take it from your reply that this gauge
won't be suitable for this form of testing?

W.