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  1. #66
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    727
    So are you guys replacing hot shot and 409 with hot shot 2 now since its so much cheaper. Any issues going to HFCs or are you literally evacuating hot shot, change schraders and re charge with hot shot 2? Any txv setting changes? I see it is about half the price.

  2. #67
    Join Date
    Jun 2013
    Location
    Montana
    Posts
    73
    Never used hotshot2 just 416a. No adjustments needed. Works great on txv and captube.

  3. #68
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,179
    Quote Originally Posted by Poodle Head Mikey View Post
    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
    ------
    i would think this kind of setup would cure almost any walkin cooler with icing issues.

    I've seen the thermostats called constant cut-in , but never bought one. Like the a12-701 , or 700

    Dont they only have one adjustment ?

    On a cooler you wouldnt want the coil getting any colder than 20 correct ??

    Isnt the "cut out" the only adjustable control on it ....

  4. #69
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    447
    The A12-700 cuts in at 37F, the A12-701 cuts in at 41F. On a R12 or r134 evap, you would be at like #2 or #3 max on the adjustment. And then some clown comes along and sets the adjuster knob to 8 or 9 and the compressor never shuts off. That works.

  5. #70
    Join Date
    Sep 2002
    Posts
    12,549
    I always thought that was the point of the constant cut-in controls - to ensure that the coil got above freezing during every off cycle so that no timed defrost control was required.

    The space temperature is controlled by the run time which is controlled by you adjusting the differential of the control. I've never never given much thought to exactly how cold the evaporator actually gets but the cut-out is adjustable from 15 to 30. So if the highest setting cut-out the compressor at 30 and the lowest setting does it at 15 - then the middle of the range would have the compressor off at a 22.5 evaporator temperature. Which is where I always set them initially. Then I tell the customer to adjust them only one number per day in the direction they want the temperature to go.

    PHM
    ------



    Quote Originally Posted by Snapperhead View Post
    i would think this kind of setup would cure almost any walkin cooler with icing issues.

    I've seen the thermostats called constant cut-in , but never bought one. Like the a12-701 , or 700

    Dont they only have one adjustment ?

    On a cooler you wouldnt want the coil getting any colder than 20 correct ??

    Isnt the "cut out" the only adjustable control on it ....
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  6. #71
    Join Date
    Apr 2010
    Location
    San Diego, CA
    Posts
    218
    I always thought that was the point of the constant cut-in controls - to ensure that the coil got above freezing during every off cycle so that no timed defrost control was required.
    That and it's an easy way to keep the food storage units under the FDA mandated temp limit.

  7. #72
    Join Date
    Aug 2009
    Location
    Maine
    Posts
    3,334
    Guess I have been doing it wrong for the last 40 or so years. Always install defrost timer, always measure the air temp. Try not to use a pump down with an out side condenser. Gets cold in the winter, don't like to over engineer things. Life is complicated enough.

  8. #73
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    447
    The Ranco constant cut in lowest temp set point ( dial setting #9 ) is 11F. R404 commercial temp apps run down to about 15F +/-2F using TEV's. Randell uses constant cut in's on their newer model pizza make tables & pizza retarders. I've tested and followed the temperature range with my Fluke 52. It's neat to test and follow the cycle.

    I've installed two constant cut in on older R12 units. They are working but in my case the temp controllers are hidden to prevent the user from adjusting and both set between #2 & #3.

  9. #74
    Join Date
    Feb 2009
    Location
    Wisconsin
    Posts
    311
    I carry the A12-701 and A12-1506. When installing, I take the first 12" of sensing cap and wind it around my pocket screwdriver creating a sensing bulb. Wedge it between the fins in the evap. and you are done. Like PHM, I set it midpoint initially. Most of the time that setting is good.
    You have to fight through some bad days to earn the best days of your life.

  10. #75
    Join Date
    Sep 2002
    Posts
    12,549

    No problem with that radius ?

    I have always been reluctant to coil the sensing tube that small. To avoid it I wind the tube around the evap - pulling the loops down into the fins.

    But you wind the sensing tube around a 1/8" diameter screwdriver? I'll have to try that next time as it sure seems like it would be easier. <g>

    PHM
    -----



    Quote Originally Posted by thermofridge View Post
    I carry the A12-701 and A12-1506. When installing, I take the first 12" of sensing cap and wind it around my pocket screwdriver creating a sensing bulb. Wedge it between the fins in the evap. and you are done. Like PHM, I set it midpoint initially. Most of the time that setting is good.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  11. #76
    Join Date
    Sep 2002
    Posts
    12,549
    I know what you mean - I used to do it wrong all those years too. But one day I thought about what I was trying to accomplish and the light went on in my head: I have to use a thermostat anyway - so why not accomplish both missions with one component? Easier, simpler, and cheaper. <g>

    Plus; I think the induced off cycle timing is better for the equipment as there is no chance of short cycling. With air sensing as soon as somebody opens the door warm air rushes in and the stat brings the compressor on. If the compressor has just shut off before they open the door the compressor tries to start too quickly. With a constant cut-in stat sensing evap coil temperature that cannot happen.

    PHM
    ------





    Quote Originally Posted by lytning View Post
    Guess I have been doing it wrong for the last 40 or so years. Always install defrost timer, always measure the air temp. Try not to use a pump down with an out side condenser. Gets cold in the winter, don't like to over engineer things. Life is complicated enough.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  12. #77
    Join Date
    Jun 2013
    Location
    Montana
    Posts
    73
    They say to make it like a paper clip andstick in the fins..but I see that mostly on freezer cases. Or the the cold control for freezers already pigtailed. They do make a tool to wind it up so you don't crack the tube.

  13. #78
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    727
    i just did one an hour ago and wrapped around an ink pen several times to make a bulb. fit perfect in evap.
    lots of great ideas on controlling temp in this thread. if you had to choose either a tstat sensing coil temp, or a pressure control only for temp control which is preferred?
    it seems like both are basically the same idea and will control defrost as well. stat maybe gets the upper hand because it wont short cycle if pressure rises from bad valves,ambient etc...
    i like both though

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