Pressure testing and leak help

chippy2 · August 22

hi.
I just added 3 radiant zones w/manifold and pressure tested that section with 40psi overnight and all good.

Separately I had to replumb and create a primary/secondary loop for baseboard zones. I pressure tested that section separately with 25psi incl boiler and it didn’t hold over night. I used soapy water every joint and nothing! Wondering if relief valve or air escape valve (closed) could be the culprit?

Also did find/fix one threaded leak at the new 3 way mixing valve I added and retested. Do you usually pressure test older systems after adding plumbing upgrades?

Any ideas on locating air loss/leak before I fill it?

PC7060 · August 22

assume you have the boiler air vent and other vents capped?

How fast does the pressure drop? Are the expansion tanks isolated from system during the test?

pecmsg · August 22

can you isolate the boiler from the systems

hot_rod · August 22

the gauge block is always a suspect. The Schrader valve, and sometimes up inside the gauge itself

Inert gas is another option, or a water test

EBEBRATT-Ed · August 22

If you can isolate the boiler it will probably be easier to just fill it with water if you can drain it easily if need be.

chippy2 · August 22

https://forum.heatinghelp.com/discussion/comment/1902478#Comment_1902478

I did not isolate the expansion tank. I left it pressurized with 20 psi for 8 hrs and it dropped to zero

chippy2 · August 22

https://forum.heatinghelp.com/discussion/comment/1902478#Comment_1902478

boiler air vent has a shutoff valve below it which I had off also

chippy2 · August 22

https://forum.heatinghelp.com/discussion/comment/1902479#Comment_1902479

unfortunately I cannot isolate the boiler

pecmsg · August 22

so no shuttle valves on the inlet and outlet of that boiler

mattmia2 · August 22

if you use water it may be easier to see water coming out somewhere.

chippy2 · August 22

https://forum.heatinghelp.com/discussion/comment/1902502#Comment_1902502

unfortunately when I moved the circulator to after the boiler to “pump away” , I replaced the flange valves with straight pipe on the inlet side 😱

pecmsg · August 23

down the road you will regret that decision.

hot_rod · August 23

https://forum.heatinghelp.com/discussion/comment/1902510#Comment_1902510

A good, healthy living circ can run 10, 15 years or more. In many cases the iso valves are seized after that many years and you drain down anyways. Those screw slot type iso valves were mostly useless after a few years. IF they did turn off and back on, they leaked around the screw anyways.

Nice to have iso if you swap or remove circs constantly, like a test wall, or you keep getting circ samples :)

pecmsg · August 23

and

It happens so isolation is needed or drain the entire system.
as the OP found out he could have isolated the boiler

hot_rod · August 24

It depends on where isolation valves are located. A valve at each side of a circulator may not isolate the boiler for draining or replacement.

I like a full port Webstone purge ball valve at the boiler return. Then with pump isolation on the boiler supply side you have isolation.

Here is a nice purge detail both boiler side and distribution side. As well as pump isolation

Pressure testing and leak help

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