Hi,
I'm thinking ahead when I go to install my new Combi boiler
pipework.

I obviously have to pressure test the pipework, to ensure the pressure
relief system works.

What test method is best - dry or wet?

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.

Can anyone give an opinion on the better methods, and tools to buy.

Thanks,

W.

In article ,
(wullie) writes:
Hi,
I'm thinking ahead when I go to install my new Combi boiler
pipework.

I obviously have to pressure test the pipework, to ensure the pressure
relief system works.

What test method is best - dry or wet?

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.

--
Andrew Gabriel

(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.

In article ,
(wullie) writes:

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?

If you are doing a wet pressure test, that implies (probably) that the
pipework is all complete. If you have a sealed system, you have the
system's pressure guage anyway. If you have a vented system, you can't
do a pressure test (unless you seal off the pipework to the header
tank). So I can't really picture how you would do a wet pressure test
using a dry pressure test guage in any case.

--
Andrew Gabriel

If you are doing a wet pressure test, that implies (probably) that the
pipework is all complete. If you have a sealed system, you have the
system's pressure guage anyway. If you have a vented system, you can't
do a pressure test (unless you seal off the pipework to the header
tank). So I can't really picture how you would do a wet pressure test
using a dry pressure test guage in any case.

Sorry, probably not explained it very well.

For testing a sealed system, I was thinking of performing a wet
pressure test.

I was originally under the impression that I could use the Screwfix
gauge, until I saw it was a "dry pressure" test tool.

I was therefore wondering if I could still use it, once the system is
filled with water, by using the Schrader value to increase the
pressure - with air.
I.e pressurise the water in the system by pumping air into it.

I suppose the pressure in a wet pressure test *should* really be
provided by either a) mains water pressure or b) a hydraulic pump.

I'm really wondering if I can buy the Screwfix tool to perform wet and
dry testing, or at least use the gauge to indicate the pressure during
a wet test.
(since I may not have the boiler connected at that point).

Anyone, any ideas?