Results 1 to 10 of 10
  1. #1
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    720

    Old federal deli case

    Worked a really old r12 federal deli case today. Now 414. Several signs i need to add charge, but head pressure as high as i think I should go. (Worth saying condenser is so old it has no fins, just tubing).
    Sight glass bubbling alot, sub cool 0 with no receiver. Suction pressure 18 with a 42 degree box. Suction line 53. Frost after txv for about 15 inches of line, but none on evap coil. Unit slowly pulled down from 51 to 41 as i added some gas. However still have above conditions with 160 head at 80 ambient.
    So I have several signs i need to add gas, but feel head pressure is already high enough. I know sh is way high?
    Is it normal for these old deli cases to pull down real slow? I'm guessing so. Should I attempt to add anymore?
    Would love to clear glass, but think head will go to high. Maybe this old ass coil design wont remove enough heat. K body semi hermetic compressor also

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,265
    You stated that the condenser has no fins. Have the fins corroded away or is this actually a bare-tube condenser?

    If t originally had fins, there's no point in going any further until you replace it. If it's a bare-tube design, I have found they work quite well as along as they're clean and have decent airflow across them.

    Is there a data plate on this box with a stated charge? These cases are critically charged...especially those with no receivers. Also, if it's a gravity coil design (no evap fans), there are usually multiple evaporator sections piped in series...three for double-duty cases with bottom storage or two without bottom storage.

    The TXV feeds the bottom coil first, then it goes to a holding coil just beneath the main shelf and then on to the top coil. The TXV sensing bulb is located after the top coil. So yes, they are slow. It's important to be patient and charge slowly as the box comes down to temperature. You may only get a clear SG once it's at temperature and the TXV starts to control.

    If you overcharge, when the TXV starts to throttle down the extra refrigerant will start to stack up in the condenser and cause the discharge pressure to skyrocket.

    At 160 psig with R414b, your condensing temp is only about 110ΊF. I wouldn't be too concerned about going a bit higher.

  3. #3
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    720
    thanks for the reply. It does have two fans in the cooler. they are along back, and coil is along front. It is an original bare tube condensor, not rotted out. No data plate or model #'s left for cooler. compressor is a kam2-0050-1aa semi hermetic. I believe from the sight glass bubbling, almost 0 subcooling, 30 sh, and the frost pattern i'm still low. I stopped adding because of head pressure, but it sounds like i should try a little more.
    I also thought about opening txv a little, but without a full liquid line that probably wont help. Maybe add a small reciever so i can get more charge without head going to high?

    What's the max high side you like to see with 414 around 80-82 ambient then? O ya- only 1 long evap coil in case bottom-2 fans

  4. #4
    Join Date
    Sep 2002
    Posts
    12,195
    Charge that guy up. A 190 lb. head pressure wouldn't scare me. Do it slow but keep adding - those old bare (painted right?) coils tended to run a little high even with R-12.

    BTW: While you are there clean it really well with soap, hot water, and a bottle brush. Simple Green will also work well.

    Check the oil level in that compressor too. With good oil in it - it might out live you. <g>

    PHM
    ------




    Quote Originally Posted by kklobas View Post
    Worked a really old r12 federal deli case today. Now 414. Several signs i need to add charge, but head pressure as high as i think I should go. (Worth saying condenser is so old it has no fins, just tubing).
    Sight glass bubbling alot, sub cool 0 with no receiver. Suction pressure 18 with a 42 degree box. Suction line 53. Frost after txv for about 15 inches of line, but none on evap coil. Unit slowly pulled down from 51 to 41 as i added some gas. However still have above conditions with 160 head at 80 ambient.
    So I have several signs i need to add gas, but feel head pressure is already high enough. I know sh is way high?
    Is it normal for these old deli cases to pull down real slow? I'm guessing so. Should I attempt to add anymore?
    Would love to clear glass, but think head will go to high. Maybe this old ass coil design wont remove enough heat. K body semi hermetic compressor also
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #5
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    720
    ok- sounds like a little more charge is the plan.
    yes painted black. i think it is already older than me, i'm only 34 lol.

  6. #6
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    720
    Just getting done with a prep table, so I will have to make it back to this gem tomorrow.

    I noticed yesterday the temp control bulb was under trays, but in the air. I'm thinking in the coil with a 38-40 degree cut in would be better. Any preferences for an ancient deli case?

  7. #7
    Join Date
    Sep 2002
    Posts
    12,195
    In general terms:

    Adjust the cut-in to a pressure equal the desired space temperature

    Adjust the cut-out to a pressure equal to a temperature corresponding to the desired temperature of the space MINUS 20 degrees.

    PHM
    -----


    Quote Originally Posted by kklobas View Post
    Just getting done with a prep table, so I will have to make it back to this gem tomorrow.

    I noticed yesterday the temp control bulb was under trays, but in the air. I'm thinking in the coil with a 38-40 degree cut in would be better. Any preferences for an ancient deli case?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  8. #8
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    720
    Sure, but it's just an air sensing stat like a white orders 16-901 but of a course a bit different /older

  9. #9
    Join Date
    Sep 2002
    Posts
    12,195

    Sorry - I was confused

    Somehow I had the idea that the space temperature was being controlled with a pressure control.

    PHM
    ------



    Quote Originally Posted by kklobas View Post
    Sure, but it's just an air sensing stat like a white orders 16-901 but of a course a bit different /older
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  10. #10
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    720
    Just got back from the old deli case. Was able to add a little more charge now that we're not in a hot pull down. It actually cooled off a little to well and slightly froze some stuff. Amazing considering how old this is. Anyhow suction pressure seems to hold well in off cycle so i think I will suggest a lp control and run off that. About 32 cut in 15 cut out (psi). I think that will be the best temp control for this. I really appreciate the help. It's amazing this is still running. I'm talking couple attic air cooled, r12 now hotshot, old ,old deli case. I guess they don't make em like this any more.

    No way a 134 cap tub
    E would run 35 years right? I know this is that old. Thanks again

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