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  1. #1
    Join Date
    Dec 2011
    Location
    Hiram, Ohio
    Posts
    214

    is this strange? (checking on my install guy again)

    My installation guy came by early yesterday afternoon to evac and hopefully release the charge on my new HP. The 150# of nitrogen that he left in the system from Sunday morning was still there..(this is what he left in it after it held 300psi overnight) He "triple evacuated" the system then pulled it down to under 250 microns, closed the valve on the pump and let it sit. He said it bounced up quickly about 90 microns, then stopped rising....sort of. I grabbed him a beer (he is a friend of my neighbor, so I have gotten to know him quite well over the years) and we proceeded to watch it very slowly continue to rise. (at least it seemed slow to me - maybe 5 microns every 90 seconds) 3 hours later the micron gauge read 1150. My guy kinda shrugged it off and said "We'll tackle it Saturday"... So my question is: Could this be a small leak in my system? Small leak in HIS system? Condensibles? Normal? thanks, Mike.

  2. #2
    Join Date
    Aug 2012
    Posts
    2,650
    moisture in system will cause microns to rise but sincre it is new ??? MAy be a leak I would pressure test a few days. Being this is new equipment all he has to do is chreck his welds, do they look good or shotty.
    My name is TooCoolforschool and I am a chronic over charger.

  3. #3
    Join Date
    Aug 2012
    Posts
    2,650
    Did he change everything? Or just the condenser?
    My name is TooCoolforschool and I am a chronic over charger.

  4. #4
    Join Date
    Dec 2011
    Location
    Hiram, Ohio
    Posts
    214
    Entire system is new, he put in a propane furnace last spring, now replacing an old AC with a HP. Welds look great to me, was flowing nitrogen when he welded, when he first charged with nitrogen had a leak where the TXV attached to the suction line in the evaporator, but tightened that and then had no more bubbles... Also, no bubbles at the two locations where the TXV attach to the liquid line at the evap., no bubbles at the welds either. This was last Saturday, he charged with nitrogen to 300psi and it held perfectly all night long. Reduced it to 150 when he pulled his guage set off, and it was still at 150 when he hooked up yesterday. Could it leak vacuum and not high pressure nitrogen? The evap has been in the plenum for weeks, but was still under pressure when he did the final install of the lineset, but the evap and lines were open for a few hours during that time, so air got in there for sure, but neither the linest nor the evap sat for days without the caps off, as far as I know. Mike

  5. #5
    Join Date
    Aug 2012
    Posts
    2,650
    He pulled his gauges off and lost 150 psi, thats strange. If its holding pressures steady over three days I would not worry, are you looking over his shoulder every minute or what? Is this the same guy that hacked in your neibors unit?
    My name is TooCoolforschool and I am a chronic over charger.

  6. #6
    Join Date
    Sep 2012
    Location
    Hebderson Ky
    Posts
    55
    I agree with the other guys. But it could also be possible that his hoses on his gauges do not have a good seal or could be leaking.

  7. #7
    Join Date
    Dec 2011
    Location
    Hiram, Ohio
    Posts
    214
    LOL, don't get the wrong idea.. this has become a laid back installation, had a few beers last night while we watched the gauge rise. He likes the conversation, we've known each other for quite some time. Anyway, after it held 300psi overnight last Saturday into Sunday, he was going to evacuate it that day but the weather was calling for rain so he refilled it to 150 and left. It didn't loose that pressure by accident, it was a change of plans. So from Sunday morning to Thursday afternoon it held 150. And no, not that same guy who hacked-in my neigbor!

  8. #8
    Join Date
    Aug 2012
    Posts
    2,650
    Good to hear. It sounded as if he lost the pressure when removing his gauges, my reading comprehension is still around tenth grade so sounds like you should be good to go.
    My name is TooCoolforschool and I am a chronic over charger.

  9. #9
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,060
    Quote Originally Posted by troyport View Post
    LOL, don't get the wrong idea.. this has become a laid back installation, had a few beers last night while we watched the gauge rise. He likes the conversation, we've known each other for quite some time. Anyway, after it held 300psi overnight last Saturday into Sunday, he was going to evacuate it that day but the weather was calling for rain so he refilled it to 150 and left. It didn't loose that pressure by accident, it was a change of plans. So from Sunday morning to Thursday afternoon it held 150. And no, not that same guy who hacked-in my neigbor!
    Let the charge loose, your readings exceed industry standards and with non-vacuum rated equipment the slight increase is to be expected.

  10. #10
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    3 hours is a long time to leave a micron gauge on even the tiniest of leaks in ANY connection could account for the rise. As for pressure testing at 150 or 300, it's ok for primary testing but a super tiny leak won't show up as a pressure drop for weeks.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  11. #11
    Join Date
    Dec 2011
    Location
    Hiram, Ohio
    Posts
    214
    Okay, I think his thoughts were maybe there is a tiny leak that didn't show up with the pressure test, or his gauges.. but I don't know. But assuming there is a leak that small, would I expect a low charge problem next month? Next year? Either way, when he pulled his gauges I would assume he lost more vacuum, and he said he will come tomorrow and pull another vacuum.. We'll see what happens. Mike.

  12. #12
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    If he's not sure, he can break the vacuum with nitrogen, change his vacuum pump oil and pull it down again but I doubt there's a problem. This round will probably pull down even further than 250 provided all of his connections are tight.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,925
    Vacuum again, and see if it holds for 15 minutes.
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