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  1. #1
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    Sep 2002
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    Static Glass Display Case

    I hate these things

    Haven't seen it in person, but a guy who sells used equipment called me up, said he plugged it in, ran for a day at his place, and he sold it

    Customer ran it 2 days , says theres a big ass chunk of ice on the evap, like bigger than it should be

    So when do you determine there is too much ice ??

    I mean , don't these normally have a nice film of ice ?

    And how do you control how thick it gets ….

    Oh … Seller told me someone apparently added a defrost clock of their own to this thing

  2. #2
    Join Date
    Oct 2011
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    Chicagoland Area
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    Static (plate) or gravity (loop or finned coil with no fan)? Gravity should have no ice and use pressure controls to control temp and have a defrost. Static should have an even build up and could use either pressure or temp controls to control temp and have no defrost.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  3. #3
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    Aug 2002
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    Southold, NY
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    If you can control it bu Pressure that works best.

    If not temperature and pump down. Defrost clock set for 1 1/2 - 2 hrs during a closed time!

    Ideally you want some icicles dripping down toward the drain.

  4. #4
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    Large chunk in one spot is probably going to be low on gas or restricted
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  5. #5
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    Thread Starter
    I guess gravity is correct word

    I remember working on one several years ago and recall spending many hours babysitting and tweaking it

  6. #6
    Join Date
    Jul 2000
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    Guayaquil, EC
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    Yep, deli case with a gravity coil. I usually set the LP control to cut out to about 15-20F SST and cut in at around 30F SST to start with.

    The single, 1-2 hr off time defrost that pecmsg posted is need to completely clear the coil every night. Don't expect to see the coil clear during the day on the off cycle because if they're set right, they won't.

    These cases respond verrrry slowly so patience is truly a virtue. After a defrost or off cycle, the TXV will be wide open but you won't see a drop in suction gas temperature and the valve throttling back to control SH for a long time...up to an hour or so. The refrigerant flows in one very long and slow circuit through each coil. Some cases have there coils in series, starting with the bottom coil, a pan chilling coil under the racks and the primary top coil. All are single passes. No distributors.

    I found with a busy store, a thermostat comes in handy as a low limit safety. Place the bulb in the back on a shelve standard and set for 32-35F. This allows you to run a slightly colder coil cut-out temp for faster recovery without freezing product during slower times of the day or at night.

    Also, as a general rule, never set a gravity coil up with pumpdown control with a liquid line solenoid. The thermostat should either shut the compressor off directlt though the contactor or by using a suction stop solenoid valve. These run essentially flooded and hold a lot of refrigerant. Most standard condensing units don't have a big enough receiver to handle the pumpdown charge.

    These cases always run better cycling on the LPC. The only better way is on a rack system with an EPR.

  7. #7
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    Quote Originally Posted by icemeister View Post
    Yep, deli case with a gravity coil. I usually set the LP control to cut out to about 15-20F SST and cut in at around 30F SST to start with.

    The single, 1-2 hr off time defrost that pecmsg posted is need to completely clear the coil every night. Don't expect to see the coil clear during the day on the off cycle because if they're set right, they won't.

    These cases respond verrrry slowly so patience is truly a virtue. After a defrost or off cycle, the TXV will be wide open but you won't see a drop in suction gas temperature and the valve throttling back to control SH for a long time...up to an hour or so. The refrigerant flows in one very long and slow circuit through each coil. Some cases have there coils in series, starting with the bottom coil, a pan chilling coil under the racks and the primary top coil. All are single passes. No distributors.

    I found with a busy store, a thermostat comes in handy as a low limit safety. Place the bulb in the back on a shelve standard and set for 32-35F. This allows you to run a slightly colder coil cut-out temp for faster recovery without freezing product during slower times of the day or at night.

    Also, as a general rule, never set a gravity coil up with pumpdown control with a liquid line solenoid. The thermostat should either shut the compressor off directlt though the contactor or by using a suction stop solenoid valve. These run essentially flooded and hold a lot of refrigerant. Most standard condensing units don't have a big enough receiver to handle the pumpdown charge.

    These cases always run better cycling on the LPC. The only better way is on a rack system with an EPR.
    Interesting on the No Pump-down.

    Cant say I've seen that issue but will look on the next one!

  8. #8
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    One i worked on yesterday. Stopped by today to check.
    36F
    Attached Images Attached Images  

  9. #9
    Join Date
    Dec 2014
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    Quote Originally Posted by icemeister View Post
    Yep, deli case with a gravity coil. I usually set the LP control to cut out to about 15-20F SST and cut in at around 30F SST to start with.

    The single, 1-2 hr off time defrost that pecmsg posted is need to completely clear the coil every night. Don't expect to see the coil clear during the day on the off cycle because if they're set right, they won't.

    These cases respond verrrry slowly so patience is truly a virtue. After a defrost or off cycle, the TXV will be wide open but you won't see a drop in suction gas temperature and the valve throttling back to control SH for a long time...up to an hour or so. The refrigerant flows in one very long and slow circuit through each coil. Some cases have there coils in series, starting with the bottom coil, a pan chilling coil under the racks and the primary top coil. All are single passes. No distributors.

    I found with a busy store, a thermostat comes in handy as a low limit safety. Place the bulb in the back on a shelve standard and set for 32-35F. This allows you to run a slightly colder coil cut-out temp for faster recovery without freezing product during slower times of the day or at night.

    Also, as a general rule, never set a gravity coil up with pumpdown control with a liquid line solenoid. The thermostat should either shut the compressor off directlt though the contactor or by using a suction stop solenoid valve. These run essentially flooded and hold a lot of refrigerant. Most standard condensing units don't have a big enough receiver to handle the pumpdown charge.

    These cases always run better cycling on the LPC. The only better way is on a rack system with an EPR.
    Thats some good info there Ice.
    Im not following the tstat tho. If in series with the LP control, the warmer one will open the circuit. If in parallel then the colder one will run the show. Or is the tstat CUT-IN allowing a colder case?
    Guess I'm confused

    Sent from my SM-G950U using Tapatalk

  10. #10
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    Quote Originally Posted by icy78 View Post
    Thats some good info there Ice.
    Im not following the tstat tho. If in series with the LP control, the warmer one will open the circuit. If in parallel then the colder one will run the show. Or is the tstat CUT-IN allowing a colder case?
    Guess I'm confused

    Sent from my SM-G950U using Tapatalk
    The thermostat should be in series with the LP so either can cycle the compressor off. When one control opens the other will remain closed. The control that cuts out will be the one to cut in and restart the compressor, so both should have the same differential. I found this useful in a busy market scenario.

  11. Likes icy78 liked this post
  12. #11
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    Thread Starter
    So the defrost should be set 1.5 hours at night

    How long during day ?

    How many times ?

  13. #12
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    Quote Originally Posted by Snapperhead View Post
    So the defrost should be set 1.5 hours at night

    How long during day ?

    How many times ?
    1-2 hours, once per day during non-business hours, like midnight.

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