Results 1 to 12 of 12
  1. #1
    Join Date
    May 2004
    Location
    Plattsburgh NY
    Posts
    176
    If I am charging up small reach in cooler, ambient temp= 70f, add 30= 100f convert to 124 psi which is proposed high side press. for 134a. This is a cap tube sys. What should temp be at condensor outlet? (liquid line)

  2. #2
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,578
    I have never checked that in 12 years of fractional H.P. service. You suction should be 11-17 psig with 10-20 degrees superheat. Put a digital thermometer in it to see the temp dropp.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  3. #3
    Join Date
    Jun 2000
    Location
    Southern States
    Posts
    108
    Originally posted by flangehead
    If I am charging up small reach in cooler, ambient temp= 70f, add 30= 100f convert to 124 psi which is proposed high side press. for 134a. This is a cap tube sys. What should temp be at condensor outlet? (liquid line)

    If all things are equal, clean and good air flow such like new. 25 to 30 deg less than discharge line temp.

  4. #4
    if it was me i would try my hardest to find factory charge & match it but i assume u tried. i normally do the +30 when i need to. it works for me & hopefully as it will for u. providing cond coil & evap are clean & box runs for at leat 15 minutes . but hey thats just me. if there is a better way i would like to know. one tech told me to stick digital therm probe inside evap coil & temp should match up with pressure. thats his way. good luck

  5. #5
    Join Date
    May 2004
    Posts
    11,986
    There is another way and it works OK when the system has been so hacked up that the factory charge will be no where close

    Charge the system with the evap motor off.

    Continue to add 2 oz at a time until it frosts back to the compressor. Stop and start the evap motor again.

    It will be very close.


  6. #6
    Join Date
    Jun 2004
    Posts
    849
    Flangehead If you are just charging the unit you discribe
    then the box temp is very hot.

    At this point your head pressure is probably have a higher
    condenser TD than 30. superheat and subcooling is pointless
    and does not mean squat at this point.


    Also since its a cap tube system then you should be more concern for the superheat not subcooling.

    Cap tube system are critical charge. I suggest you weigh in the charge and if you want to check all the SH and SC then check it when the box is at the proper temp.

    When you first start a Fractinal HP unit. the head pressure are a lot higher due to very high evap load. when the load decrease so does your head pressure.
    Hope this helps.

  7. #7
    Join Date
    Feb 2003
    Location
    NH & Cebu
    Posts
    1,611
    Never in my life have I checked superheat or subcool on a critically charged system. Weigh in the charge and walk away. It doesn't have to be that complicated

  8. #8
    Join Date
    Dec 2004
    Location
    Puyallup,WA.
    Posts
    51
    I agree with lusker, you can charge the system slowly until you see the frost line coming out of the evap then pull some out to take the frost line back to evap.

  9. #9
    Join Date
    Mar 2002
    Location
    fort walton beach fl.
    Posts
    790
    Originally posted by coldmilk
    I agree with lusker, you can charge the system slowly until you see the frost line coming out of the evap then pull some out to take the frost line back to evap.
    Thats not what lusker said,disconnect evap motor till a frost line comes back to compressor, then reconnect motor and charge SHOULD BE CLOSE.Never tried this method butwill try soon.If there is no data plate with the correct weight in charge, i normally charge till my highside reachs about 115 degrees,i watch the box temp come all the way down to temp, when the box temp reachs idea conditions i shoot for a 20 degree suction and between 105 and 120 degree head depending on the superheat.

  10. #10
    Join Date
    May 2004
    Posts
    11,986
    Originally posted by smurphy
    Originally posted by coldmilk
    I agree with lusker, you can charge the system slowly until you see the frost line coming out of the evap then pull some out to take the frost line back to evap.
    Thats not what lusker said,disconnect evap motor till a frost line comes back to compressor, then reconnect motor and charge SHOULD BE CLOSE.Never tried this method butwill try soon.If there is no data plate with the correct weight in charge, i normally charge till my highside reachs about 115 degrees,i watch the box temp come all the way down to temp, when the box temp reachs idea conditions i shoot for a 20 degree suction and between 105 and 120 degree head depending on the superheat.
    smurphy

    You put all of that together, shake it up real good, it is called experiance.

    When you have to fly by the seat of your pants on a cap system the above is where I start and hopefully end.


  11. #11
    Join Date
    May 2000
    Location
    Monmouth Junction-NJ-USA
    Posts
    6,001
    Yep after 5 or 6 u will get the hang of er. Not rocket science.
    If you really know how it works, you have an execellent chance of fixin' er up!

    Tomorrow is promised to no one...

  12. #12
    Join Date
    Mar 2004
    Location
    Connecticut
    Posts
    34
    I agree with coldmilk but will try out what Lusker said.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event