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  1. #53
    Join Date
    Jun 2013
    Location
    Montana
    Posts
    73
    PHM you are correct that R417C is Hot-Shot 2, a R12 drop-in.

  2. #54
    Join Date
    May 2010
    Location
    Oxford, UK
    Posts
    338
    If its short cycling because the compressor head valves are letting by and customers got no money, fit a check valve in the suction line just before the compressor and fit the LP switch before the check valve so it will still maintain the correct evaporator pressure. No need to change the refrigerant or fit solenoids, stats etc.

    Sometimes you gotta do what you gotta do even if its not ideal.

  3. #55
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    727
    this sounds like a perfect bandaid idea. I like it. I reset controls as PHM suggested, went a little higher to compensate- i believe 40-20 psi, and it has been running a few days i assume or they would have called. I'll be back there tonight for a different cooler, and will check. this could be good though. It was actually cooling ok, just had suction rising to fast. thanks for another idea

  4. #56
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    1,299
    Quote Originally Posted by monkeyspanners View Post
    If its short cycling because the compressor head valves are letting by and customers got no money, fit a check valve in the suction line just before the compressor and fit the LP switch before the check valve so it will still maintain the correct evaporator pressure. No need to change the refrigerant or fit solenoids, stats etc.
    I don't think a check valve will work, since you aren't trying to pump down the system. I don't think you ever diagnosed that the valves were actually not holding. If the valves are holding, and you add a check valve, it will still work exactly the same. It seems to me that the system is shutting off and the pressures might just be naturally rising because the condensing unit is in a warm place.

    If you really want to, you could replace the low pressure control with a conventional thermostat. No need to cut the system open and add a pump down solenoid, just run the system like it is, but with a thermostat instead of the pressure control.

    If you do this, it would probably be a good idea to also add a defrost timer to it. Another option might be to leave the l.p. control in there wired in series with the thermostat and set it so it will open up and act like a defrost control if the pressure gets too low.

    Another option, is to go with the time delay relay as mentioned before, along with a contactor or something like this RIB relay (that is good for 20 amps) to control the compressor...
    http://www.grainger.com/Grainger/wwg...rue&sst=subset

  5. #57
    Join Date
    Sep 2002
    Posts
    12,569

    R-417 is a drop-in for R-12, R-134, etc.

    You may be thinking of R-417A - which is a replacement for R-22 - comes in a light green cylinder.

    But what I am trying to draw your attention to is R-417 - which is a drop-in for R-12 and the other medium pressure refrigerants. And it is presently available at lower costs than the other substitutes. Icor calls it: HotShot2

    PHM
    ------



    Quote Originally Posted by lytning View Post
    Ahh, I must be thinking of 416. Light green can?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  6. #58
    Join Date
    Sep 2002
    Posts
    12,569
    The more standard and less expensive repair option would be to install a constant cut-in thermostat sensing evaporator temperature to control the box temperature - use 37 or so and on each cycle the evap coil has to de-frost before the compressor will come back on. Much easier and less expensive than redesigning the whole machine.

    Any dam fool can get complicated - it's Simplicity that is Genius. <g>

    PHM
    ------




    Quote Originally Posted by ammoniadog View Post
    I don't think a check valve will work, since you aren't trying to pump down the system. I don't think you ever diagnosed that the valves were actually not holding. If the valves are holding, and you add a check valve, it will still work exactly the same. It seems to me that the system is shutting off and the pressures might just be naturally rising because the condensing unit is in a warm place.

    If you really want to, you could replace the low pressure control with a conventional thermostat. No need to cut the system open and add a pump down solenoid, just run the system like it is, but with a thermostat instead of the pressure control.

    If you do this, it would probably be a good idea to also add a defrost timer to it. Another option might be to leave the l.p. control in there wired in series with the thermostat and set it so it will open up and act like a defrost control if the pressure gets too low.

    Another option, is to go with the time delay relay as mentioned before, along with a contactor or something like this RIB relay (that is good for 20 amps) to control the compressor...
    http://www.grainger.com/Grainger/wwg...rue&sst=subset
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  7. #59
    Join Date
    Jun 2013
    Location
    Montana
    Posts
    73
    I was thinking of 417a because you only said 417.

  8. #60
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    727
    Thanks for all the replays.
    As of now i took PHM's suggestion, set a 20 psi differential, and tonight i was back there. Still cooling. Amazing- this is a plywood/2x4 box. Nothing but a fan cycle and lp control for controls...
    The t-stat idea- if i understand right is take the wire out of lp control, run through a stat like a 16901 and back, so both t-stat and lp have to close to run compressor, but if either opens it will shut off? I like the idea. It is funny the effort put into something like a plywood beer walk in. But hey-it's essential to the bar right?.......

  9. #61
    Join Date
    Sep 2002
    Posts
    12,569
    Yes to the wiring - No to the logic.

    You can well control the space temperature with either a LP control or a thermostat. But since you already have it working well on a LP - why add the thermostat?

    Nonetheless; if you do add a thermostat (I would want it sensing evap temp - not air temp) then, yes; you wire the stat in series with the LP control.

    But I wouldn't want both controlling space temperature. The LP would become a safety control and the stat would be the operating control. I would set the LP at about 5 and 15 if the stat was added.

    But, if it were me; I wouldn't add the stat. <g>

    PHM
    ------



    Quote Originally Posted by kklobas View Post
    Thanks for all the replays.
    As of now i took PHM's suggestion, set a 20 psi differential, and tonight i was back there. Still cooling. Amazing- this is a plywood/2x4 box. Nothing but a fan cycle and lp control for controls...
    The t-stat idea- if i understand right is take the wire out of lp control, run through a stat like a 16901 and back, so both t-stat and lp have to close to run compressor, but if either opens it will shut off? I like the idea. It is funny the effort put into something like a plywood beer walk in. But hey-it's essential to the bar right?.......
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  10. #62
    Join Date
    Apr 2010
    Location
    working overtime
    Posts
    848
    maybe i missed it as i skipped through but is yor condenser inside or outside. if its outside using a pressure control for temp may give you some problems.

  11. #63
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,181
    i just tried that on a deli prep table and it didnt work well. My intention was to have the sensing bulb on the Coil to sense case temp , and shut off compressor when desired 36 was reached. What ended up happening was short cycling. When they opened the doors and let the kitchen heat in , the coil was getting really cold of course , trying to lower temp , and the thermostat thought the case was cold so it kept turning off unit , but then under a minute would kick back on. Compressor hated that about the 3rd time.

    I was hoping it would work , because that would have been a great way to prevent icing on the coil.

    Ended up leaving the bulb in the air

  12. #64
    Join Date
    Apr 2010
    Location
    working overtime
    Posts
    848
    I always used a johnson a 419 etc. I put the sensor in the coil I would set for 22 degree with 15 differential also I would give it a decent time delay. I could keep my box temp 35 degrees with a swing of a about 3 degrees +or

  13. #65
    Join Date
    Sep 2002
    Posts
    12,569

    That was improper application and control logic

    To control the space temperature by sensing evaporator temperature you have to inject a long on-cycle with at least a 15 to 20 differential.

    Any adjustable-differential temperature control will work but a constant cut-in control makes it simple. And if the coil has no insertion well you can just wind the long sensing tube around the coil and pull it down into the fins.

    PHM
    ------

    Quote Originally Posted by Snapperhead View Post
    i just tried that on a deli prep table and it didnt work well. My intention was to have the sensing bulb on the Coil to sense case temp , and shut off compressor when desired 36 was reached. What ended up happening was short cycling. When they opened the doors and let the kitchen heat in , the coil was getting really cold of course , trying to lower temp , and the thermostat thought the case was cold so it kept turning off unit , but then under a minute would kick back on. Compressor hated that about the 3rd time.

    I was hoping it would work , because that would have been a great way to prevent icing on the coil.

    Ended up leaving the bulb in the air
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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