Results 1 to 11 of 11
  1. #1
    Join Date
    Jun 2005
    Posts
    19
    Can anyone please explain this method to me. I have been reading in all three of the leading hvacr texts and cannot find a good explanation of this method of liquid recovery in any of them. It's all the hose hookup locations that I need to see more clearly. For example,I understand that the recovery unit's inlet valve connects to the vapour valve of the cylinder (and is my understanding thus far correct?), but I loose all further understanding of how the recovery unit is connected to the ac unit (again, for liquid refrigerant recovery- the push/pull method)?
    Any help is appreciated.

  2. #2
    Join Date
    Jul 2005
    Posts
    38
    A push-pull method of removing refrigerant is accomplished by connecting the liquid line fitting on
    the system to the liquid line fitting on the recovery tank. The suction line of the recovery unit is
    connected to the vapor fitting on the recovery tank, and a connection is then made from the
    discharge (outlet) of the recovery unit, back to the system. When the unit is started, vapor is drawn
    out of the recovery tank from the vapor port of the tank and condensed in the recovery unit. A very
    small amount of liquid is then pushed back into the system where it flashes to a vapor to build
    pressure and push more liquid from the system into the recovery tank. A sight glass in the liquid line
    between the system and liquid-connection of recovery tank is useful for monitoring the liquid
    recovery. When no more liquid is being recovered, the recovery unit is reconnected for direct
    vapor recovery. Hope this helps.

  3. #3
    Join Date
    Feb 2005
    Location
    Barrie, Ontario
    Posts
    4,622
    I like to use a scale on my recovery tank. When it stops climbing, it's time to go to vapour recovery.
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  4. #4
    Join Date
    Jul 2003
    Location
    Orange County N.Y.
    Posts
    1,176
    Originally posted by gruntly
    I like to use a scale on my recovery tank. When it stops climbing, it's time to go to vapour recovery.
    I'm not sure that I'm thinking the same thing that you are when I hear the phrase push/pull recovery. Most of the jobs I get to use this process on have transfer tanks
    on site that are capable of holding anywhere from a few hundred pound of refrigerant to a few tons of refrigerant depending on the size of the equiptment of course.

    ...Ron

  5. #5
    Join Date
    Apr 2002
    Location
    Omaha, NE
    Posts
    1,561
    Originally posted by jimkim
    Can anyone please explain this method to me. I have been reading in all three of the leading hvacr texts and cannot find a good explanation of this method of liquid recovery in any of them. It's all the hose hookup locations that I need to see more clearly. For example,I understand that the recovery unit's inlet valve connects to the vapour valve of the cylinder (and is my understanding thus far correct?), but I loose all further understanding of how the recovery unit is connected to the ac unit (again, for liquid refrigerant recovery- the push/pull method)?
    Any help is appreciated.
    Some links with explanation of push/pull refrig. recovery

    http://www.bacharach-inc.com/PDF/Ins.../2079-1130.pdf

    http://www.actoolsource.com/pdf/R-41...W4COLD_COM.pdf

  6. #6
    Join Date
    Feb 2005
    Location
    Barrie, Ontario
    Posts
    4,622
    Yup..That's 'er

    For the Yellow Jacket one I have a better use for the ice though

    Best part about push/pull is there is very little pressure increase therefore the liquid moves faster and when you change over to vapour recovery, it draws down quicker as well.

    I've used ice or a hose in a five gallon pail to keep the recovery tank pressure as low as I could.

    Do yourself a favour. Take some time in the garage and practice transfering refrig from one recovery tank to another with a recovery unit, liquid and vapour. This'll give you a better picture in your head as to what you want to happen when you connect the hoses. I use a scale instead of a sight glass. Basically does the same thing. Just tells you when the liquid is out and all you've got left is vapour.



    [Edited by gruntly on 07-09-2005 at 04:09 PM]
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  7. #7
    Here is my method of recovery.


    Stick a pebble underneath the schrader valve cap on the system and come back later.

  8. #8
    No .. jus kidding.



    Seriously though ... here is what I recomend for the best times in recovery.


    Do it in the morning whenever possible so it's cool.

    Next ... submerge the recovery cylinder inside a container mixed with ice and salt.
    The cylinder temp will drop so low the refrigerant will RUSH into the recovery cylinder!

    If your servicing RTU's, shade of any kind also does wonders to speed recovery.


    "PUSH-PULL" .... sounds kinda like a tug of war to me...

  9. #9
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    Why not just get a decent unit whcih sucks liquid. Hook it up and wait till it's done. Much easier. Mine sucks a pound of liquid a minute.

  10. #10
    Join Date
    May 2002
    Location
    Baton Rouge, Louisiana
    Posts
    3,959
    If your recovering freon on a decent size system and using the 100# tanks, get a piece of 12" joval, put it together, put over the tank and fill with ice, works really good.
    Quote Originally Posted by MatrixTransform View Post
    very soon it is you that will be pwned

  11. #11
    Join Date
    Jun 2005
    Posts
    19

    Thanks for the info.

    Thanks for the info everyone -and thanks snewman for hte internet links.

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