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  1. #27
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,586
    I am a firm believer in adding a sporlan filter drier to all systems at the air handler. That being said i would not expect and non-refer man to think the only way to remove moisture from a system is thru a vac pump. I have had systems so full of water that you had to hammer the pipes to move the ice blockage which you could hear banging down the pipe to the rack. You know the system cleaned up fine and we never put a vac pump on it. I have also had small systems (under 1 h.p) that have had moisture problems (moisture freezing in TXV)which were solved with no micron gauge or the customer having to pull the cooler of all his product. This is all achieved thru filter drier technology. I do believe the most importent thing to do is remove all non-condensables and have a relatively clean system and a good filter drier. I am not saying that a good dry system is not assured using a micron gauge and nitrogen, but good refrigeration practices can be achieved with non of the hype. I have a supco micron gauge i have used a few times on troubled systems that had severe moisture contamination caused by a broken H20 evap loop but thats about it.

    When i talk of small systems I am refering to any system under 5 tons.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  2. #28
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,586
    I have been with this employeer for 9 years so i get to see my work still running in supermarkets in Connecticut. This includes mini-splits ect and i have yet to see a failure of my installs i could point to moisture.

    I do not condone hackery and i always evac a system and do a proper leak check.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  3. #29
    Join Date
    Apr 2005
    Location
    illinois
    Posts
    257
    Beenthere
    One of the contractors I am considering doesn't use nitrogen for brazing and uses the U tube. He has good references and is a comfort specialist for A/S. I don't want to dismiss him from consideration just because his methods are older. If the ash causes problems early on and the eqipment is under warranty I might take the chance. If it will be a long term problem then there is more potential expense for me.
    Assuming that he is pulling a vacuum on the lines would a U tube manometer be able to tell him that the vacuum is strong enough. He say he has been doing it that way for 30 years.

  4. #30
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,120
    Freeze, I think your talking about shell filters, with valves to change out the core. Some thing you don't find on little resi a/c's.

    If we find a sight glass on a chiller showing moisture we keep changin filters till it shows its dry, and no moisture in the oil.
    On rack systems don't you check the oil for moisture on a regular basis?

    I think the general topic is pulling a vacuum on a new system.
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  5. #31
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,120
    Heatseeker, the u tube has been around longer then the micron guage.

    So there should be no problem there.

    Again IMO its a gamble without nitrogen, but I work on stuff thats been running for 30 years and they didn't use nitrogen.

    I would recommend getting an extended warranty though.
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  6. #32
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,586
    I am talking about c163 driers(some flair some not) and i put a 303 on any 1/2 hp or larger unit that i suspect has a moisture problem. I am not much of a believer in suction filters as the pressure drop goes un-noticed and it will eat the compressor.


    And no we do not test rack oil for moisture, i think we would see temp problems before we had oil moisture due to operating at lower temps.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  7. #33
    Join Date
    Apr 2005
    Location
    illinois
    Posts
    257
    Beenthere
    Thanks for your help. I would be getting a 10 year parts and labor agreement so I don't think I am taking too big a risk. From all the talk I have read on this site about nitrogen and micron gauges I lost some faith in this contractor.

  8. #34
    Join Date
    Sep 2003
    Posts
    1,311
    The International Mechanical Code, along with many manufacturers, requires evacuation to at least 500 microns. 500 microns is about .02" mercury above absolute zero. I don't think that the U-tube manometers of today are set up for such a fine measurement. Using a water manometer won't work, not that it would have to be about 34' high, but because the water in the manometer would vaporize before the evacuation is reached.

  9. #35
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    beenthere

    " Black, which came first, 29.6"mercury, or 500 microns."

    I am sure that 29.6" merc came first, only problem is that 29.6" mercury is about 10,000 microns. 500 microns is equal to about 29.97" mercury. Pretty hard to see on a u tube. Truth be told, the boiling temp of water even at 10,000 microns is 53 degrees, A funny thing is that Ford service manuals only call for a vacuum of 25,000 microns which puts the boiling temp at over 80 degrees, wonder why so many vehicle comps fail.



  10. #36
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,295

    Adding

    Originally posted by Black Adder
    beenthere

    " Black, which came first, 29.6"mercury, or 500 microns."

    I am sure that 29.6" merc came first,
    only problem is that 29.6" mercury is about 10,000 microns.

    500 microns is equal to about 29.97" mercury.
    Pretty hard to see on a u tube.

    Truth be told,
    the boiling temp of water even at 10,000 microns is 53 degrees,

    A funny thing is that Ford service manuals only call for a vacuum of 25,000 microns which puts the boiling temp at over 80 degrees, wonder why so many vehicle comps fail.

    Black ADDER, .. Those #s don't seem to ADD up right
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  11. #37
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,120
    sadlier, we're talking a Mercury u tube, not water.
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  12. #38
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,120
    Heatseeker, your welcome.

    And hope everything works out great for you, and you keep us up dated.
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  13. #39
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,295

    Question Vacuuming

    Originally posted by heetseeker
    I asked my contractor if he pulls a vacuum after he charges the system ... Is he correct?
    How do you vacuum AFTER a charge?
    ... Timing might be off just a tad.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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