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Valves Leaking By

My house has two air conditioning systems, one on the first floor that I installed DYI this spring, and it's working great. The second is a hi-velocity system in my attic which has a bunch of issues, the computer boards died this was a common issue with this unit and was the hvac equivalent of recalled. But since the unit is out of warranty and the replacement part costs more than a standard air handler delivered. Additionally it never kept up on hot days even after having the refrigerant levels checked by two different professionals. To add to that, it was always loud and then a racoon got into my attic and pulled out all the ducts anyway.

I've finally gotten around to redoing all this duct work with standard duct work, and replacing the indoor air handler with a standard air handler. The existing condenser unit is running perfectly and is only about 10 years old, factory charged with 410A so not an old unit.

I started this project this morning by pumping down the refrigerant into the condenser it took a lot less time than I expected. But there seems to be an issue with the valves keeping the charge in the unit.

I expected to find standard king valves to close instead I found these:

I think they are refrigerant ball valves? They are both leaking from the packing, when I took the covers off both released a little puff of gas. The bigger issue is that I was able to pump this system down to dead 0 with the compressor by shutting the high side and leaving the low side open, then shutting the low side valve when the gauge hit 0.

But after leaving the system to sit for about an hour I'm seeing that one or both of them are leaking by the pressure has gone up from 0 on both sides to about 10PSI.

If I were a pro, I would likely just fully recover, but not being one I don't have a recovery machine and i was hoping to avoid buying one, as the compressor could do that for me. My question is at this point is there anything I could do to help these seal up? Are there any temporary caps I could put on the lines or something like that? I still need to re-do the duct work and was hoping that I could get the AHU out of the way before starting that work. But clearly if I removed it now, I'd likely end up loosing a good amount of charge before I got the new AHU installed. Additionally with it like this, I'm not sure I could sliver up the new unit without leaks. And even if I could I don't know how I could pull a good vacuum with these leaking.

Any suggestions would be appreciated.


    EBEBRATT-Ed Member Posts: 15,633
    Even though you pumped it down it could be the valves leaking or it could be residual refrigerant boiling off. Open the suction and pump it down again. You won't get it to 0 under any circumstances.

    Putting the caps on the valves should stop the stem leakage. They can leak slightly, check with soap bubbles.

    If the valves are leaking by slightly you could you could cut the lines and solder caps on. You will have to bleed the pressure out through the service tappings so you can solder.

    You really need a recovery machine. shouldn't be doing this without one.

    Why not get a tech to recover the charge and recharge when you are done. Replace the valves if needed
  • johncharles
    johncharles Member Posts: 50
    Thanks @EBEBRATT-Ed I tried that and it worked.

    In answer to your first question I wasn't sure I could get a tech out who wouldn't insist doing the whole job not just the recovery.

    Second, I noticed from 0 to 1 hour the pressure rose to around 10PSI but from 1 to 2 hours the pressure stayed at 10PSI. So I think you are right about stuff boiling off. I tried again, and its now been sitting for almost 2 hours at zero.

  • mattmia2
    mattmia2 Member Posts: 9,750
    Tht was going to be my suggestion, see if it continued to rise as you waited longer. Probably just refrigerant heating and expanding or evaporating in parts of the system that got cold as you pumped it down.