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  1. #1
    Join Date
    Feb 2007
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    Bellingham, WA
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    115

    How long should a vacuum be pulled?

    The installed indicated that he will have to take out the freon and repair the pressure sensor and then put back the freon. How long should the installer pull a vacuum before filling up the freon? Are you allowed to reuse the same R-410 freon?

  2. #2
    Join Date
    Feb 2007
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    It isn't the amount of time, it's how clean he gets the system when doing it. It can take a lot longer to clean a large system than a small system.

    Did he tell you how long he thought it would take? Did he tell you he could use the old refrigerant over? Did he tell you he'd put new refrigerant in?

  3. #3
    Join Date
    Jan 2004
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    PA
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    So he found the reason your HP wasn't running.

    Is he going to replace the filter drier, he should, its required.
    He should run the vacuum pump long enough to pull a 500 micron vacuum.

    He can reuse it. I wouldn't.
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  4. #4
    Join Date
    Aug 2002
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    Southold.calm
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    6,336
    Quote Originally Posted by beenthere View Post
    So he found the reason your HP wasn't running.

    Is he going to replace the filter drier, he should, its required.
    He should run the vacuum pump long enough to pull a 500 micron vacuum.
    And hold 500 for a while

  5. #5
    Join Date
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    Quote Originally Posted by pecmsg View Post
    And hold 500 for a while
    Why not break the 500 with nitrogen and pull it down again?

  6. #6
    Join Date
    Feb 2007
    Location
    Bellingham, WA
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    Quote Originally Posted by beenthere View Post
    So he found the reason your HP wasn't running.

    Is he going to replace the filter drier, he should, its required.
    He should run the vacuum pump long enough to pull a 500 micron vacuum.

    He can reuse it. I wouldn't.

    Yah, he determined that the pressure sensor was not working correctly. Thanks for your prior information Beenthere.

    Is there anything else he should IDEALY replace besides the filter and the freon?

  7. #7
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    That about covers it.
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  8. #8
    Join Date
    Jul 2005
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    5,576
    500 microns or lower, however long that takes. The dryer must be replaced, or one installed if there isn't one. The vacuum will not remove all the moisture from a 410a system. That's why the dryer is required. The refrigerant "can" be reused in the system that it was taken out of if the right proceedures are used. On smaller systems the added labor can cut into any potential savings in reusing the old refrigerant. I've reused the old refrigerant several times. I don't know of any valid objections to doing this when it's done right. It can cut into profits, but then so can lost business. On most smaller systems the savings aren't going to be great enough to warrant the extra effort involved in reusing the old refrigerant. On larger systems the savings can be tremendous.

  9. #9
    Join Date
    Jul 2006
    Location
    MN
    Posts
    173
    "It isn't the amount of time, it's how clean he gets the system when doing it. It can take a lot longer to clean a large system than a small system"

    Sorry I just went through this with a tech today again when he wanted to leave a pump on overnight and felt a need to clarify this.
    Not dissing on anyone but The vacuum pump doesnt clean a system it only removes air and moisture or non condensables. The filter/drier filters (cleans) the refrigerant and oil and catches dirt and debris.
    It doesnt take too long to pull a proper vacuum it may depend somewhat on the size of the pump but most resi systems just are not that big.

  10. #10
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    PA
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    Shouldn't use a big vacuum pump on resi systems.
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  11. #11
    Join Date
    Feb 2007
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    Other than a burn out, how would you get dirt in a system. Most of the time it's just moisture. I never leave a pump on overnight. I bring it down and break the vacuum with nitrogen. Do that 3 times, and it can do a better job than leaving a pump on overnight.

  12. #12
    Join Date
    Jan 2004
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    PA
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    I've left a pump on over night more then once.

    Those dang 40 ton condensers with barrels and 180' linesets just take time to get down.
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  13. #13
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    Never worked on a 40 ton system, but I have worked on 28gph 4M btu boilers. Know what a Bimba valve is?

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