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  1. #1
    Join Date
    Dec 2009
    Posts
    140

    Parallel Vacuum Pumps

    I have thought of making a fitting to pair two vacuum pumps together with some copper tube.
    Something I could easily connect when I want a really quick good vacuum when I only have 2 places to connect on a system.
    This is what I was thinking..... thoughts?

    This would take my 6CFM pump to a 12CFM pump in seconds... Name:  photo (2).jpg
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  2. #2
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    I think it would be kind of pointless if you only have 2 connection points.
    It may get you down below 5000 microns a little faster, but most likely will have little impact on overall evacuation speed, especially pulling through a refrigerant manifold and service hoses.

    On the other hand, you will get a MASSIVE reduction in evacuation time if you delete the manifold and service hoses, and use a vacuum tree with two 3/8" or 1/2" vacuum hoses between the pump and core removers on the service ports on the unit.

    If you are currently evacuating through a service manifold and hoses, with the valve cores in place in the service ports, you could cut your evacuation times in half just by removing the cores, and using hoses with no core depressors.
    If more government is the answer, then it's a really stupid question.

  3. #3
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    197
    If you only have two quarter inch service valves it is pointless to use two pumps.

  4. #4
    Join Date
    Dec 2009
    Posts
    140
    Quote Originally Posted by mark beiser View Post
    I think it would be kind of pointless if you only have 2 connection points.
    It may get you down below 5000 microns a little faster, but most likely will have little impact on overall evacuation speed, especially pulling through a refrigerant manifold and service hoses.

    On the other hand, you will get a MASSIVE reduction in evacuation time if you delete the manifold and service hoses, and use a vacuum tree with two 3/8" or 1/2" vacuum hoses between the pump and core removers on the service ports on the unit.

    If you are currently evacuating through a service manifold and hoses, with the valve cores in place in the service ports, you could cut your evacuation times in half just by removing the cores, and using hoses with no core depressors.
    Fantastic reply!
    Guys like you are what this trade needs.
    You gave me a clear answer with ways to improve.
    Thanks

  5. #5
    Join Date
    Jan 2004
    Posts
    69
    FWIW I have used 7/8 soft copper to pull vacums on rack with my pumps mighta been a little larger then yours they were some pretty good sized Kinneys

  6. #6
    Join Date
    Dec 2009
    Posts
    140
    Quote Originally Posted by aprophet View Post
    FWIW I have used 7/8 soft copper to pull vacums on rack with my pumps mighta been a little larger then yours they were some pretty good sized Kinneys
    Any pictures of that rig??

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,947

  8. #8
    Why wouldn't you just buy a 12 CFM Vacuum Pump....

  9. #9
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    20,261
    Bigger pumps do not necessarily pump faster... CLEAN oil helps.

    What is noted above about ditching the manifold and using core tools is the key to faster vacuums.

    OTOH: If one can manage their workflow, get the system closed up and let the pump chug along for 45 min to an hour... one will get the deep vacuum they want/need that way.

    Now if you are just determined to use two pumps, you could use a 4 valve manifold and connect one pump each to the 3rd and 4th hose... be an interesting experiment to determine if it really helped. Remember to do it on NEW equipment... as drawing moisture and refrigerant trapped in oil out of a replacement or repair (even the lineset) will taint the test results. Change the oil in the pump before each cycle of the test to get accurate results.
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  10. #10
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,947
    Quote Originally Posted by rizer68 View Post
    Why wouldn't you just buy a 12 CFM Vacuum Pump....
    Kinda like trying to run a firehose through a 1/4" line....


  11. #11
    Join Date
    Aug 2009
    Location
    Maine
    Posts
    2,588
    Got to be careful with that. Vacuum to fast (cfm) and you could freez any moisture. I use a 10cfm, but always use the gas ballast valve for about 5 minutes to slow things down a bit.
    Quote Originally Posted by rizer68 View Post
    Why wouldn't you just buy a 12 CFM Vacuum Pump....
    .

  12. #12
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,947
    Quote Originally Posted by lytning View Post
    Got to be careful with that. Vacuum to fast (cfm) and you could freez any moisture. I use a 10cfm, but always use the gas ballast valve for about 5 minutes to slow things down a bit.


    .
    In many cases, the larger vacuum pumps are severely limited by the size of the hoses used to evacuate with.

    You aren't going to get a full 10 or 12 CFM flow through a 1/4" set of hoses and a normal service manifold.

  13. #13
    Join Date
    Oct 2012
    Location
    Wisconsin
    Posts
    2,664
    Like others have said, eliminating the gauge manifold, taking out the shrader cores, and using larger hoses will really improve things. I used to use a 4-Valve manifold and pull a vacuum through that. Now I use two or three 1/2" hoses hooked directly to a tee on my vacuum pump. It is almost unbelieveable how much faster you can pull a good vacuum.

    If you really want to use two pumps, braze in some access points on the liquid and suction line at the evaporator, then have one pump hooked to the condensing unit, and one hooked to the evaporator. That would be much better than manifolding them together, but would most likely be unnecessary.

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