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  1. #27
    With the technology today, and for best product temp control, its a simple solution. Thermostat, solenoid, and defrost clock. Defrosts are totally dependent on climate, but 4 times a day, at 45 minutes apiece will ensure a 100 percent clear coil, but not warm up enough that the customer will notice. If anyone asks you to anything different, they are cutting corners, and trying to save money on the install. If you're not going to do it properly on the install, don't bother. You seem like you have the right attitude. Keep up the good work, and don't listen to the guys wanting to save the customer $10, and cutting corners.

  2. #28
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,769
    Quote Originally Posted by traviscmatthews View Post
    With the technology today, and for best product temp control, its a simple solution. Thermostat, solenoid, and defrost clock. Defrosts are totally dependent on climate, but 4 times a day, at 45 minutes apiece will ensure a 100 percent clear coil, but not warm up enough that the customer will notice. If anyone asks you to anything different, they are cutting corners, and trying to save money on the install. If you're not going to do it properly on the install, don't bother. You seem like you have the right attitude. Keep up the good work, and don't listen to the guys wanting to save the customer $10, and cutting corners.
    Way too much.
    Officially, Down for the count

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    Liberalism-Ideas so good they mandate them

  3. #29
    Join Date
    Dec 2004
    Posts
    509
    Did not read through entire thread so my apologies if this has been covered. I always prefer controlling temp with a lpc for a few reasons.

    1. Offers compressor protection
    2. Kiss timeclock can't fail if it's not there
    3. Customers can crank stat down but I control how low it will go
    4. Saves nuisance calls from iced up coils due to door being left open or fans turned off because it's self regulated.
    5. Maintains better product integrity
    6. Better energy efficiency
    7. Compressor life extended because it cycles better


    Sidenote regarding blends

    They are a bit trickier what you need to member is that they enter as a liquid and exit as a vapor and only in the center are they a true saturated state.

    For example say you are looking for a co evaporation temp of 15degrees and your refrigerant has a corresponding bubble point of 10lbs and a dew point of 20lbs the correct co pressure is 15lbs.

    What that does is compensates for the glide and should produce 15 degrees at the center point in your coil. It sounds more confusing then it is but it does work.

  4. #30
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    471
    Johnson Controls A419 works well. Solved two different icing issues without timers. Both older systems with high user activity.

  5. #31
    Join Date
    Nov 2010
    Posts
    50
    Quote Originally Posted by Eadam1985 View Post
    i just started doing work at this resturant and had a walk in freezer that was icing up i couldnt figure out why defrost work and pressures were fine long story short the manager would shut off the fans and leave the door open when they would load the freezer.
    The defrost fans have to be interlocked with the thermostat and the liquid line solenoid valve. Any time the switch is off the freezer pumps down. I can't imagine anyone with a brain wiring it without this simple protection.

  6. #32
    Join Date
    Nov 2010
    Posts
    50
    Quote Originally Posted by gas_n_go View Post
    Did not read through entire thread so my apologies if this has been covered. I always prefer controlling temp with a lpc for a few reasons.

    1. Offers compressor protection
    2. Kiss timeclock can't fail if it's not there
    3. Customers can crank stat down but I control how low it will go
    4. Saves nuisance calls from iced up coils due to door being left open or fans turned off because it's self regulated.
    5. Maintains better product integrity
    6. Better energy efficiency
    7. Compressor life extended because it cycles better


    Sidenote regarding blends

    They are a bit trickier what you need to member is that they enter as a liquid and exit as a vapor and only in the center are they a true saturated state.

    For example say you are looking for a co evaporation temp of 15degrees and your refrigerant has a corresponding bubble point of 10lbs and a dew point of 20lbs the correct co pressure is 15lbs.

    What that does is compensates for the glide and should produce 15 degrees at the center point in your coil. It sounds more confusing then it is but it does work.
    If the condensers are outside then your LPC is being used in the pump down. In my AO the cut out is set for 1lb and the cut in is about 15lbs. When it's -30 outside the LPC still has to be able to make.

  7. #33
    Join Date
    Jan 2010
    Posts
    6,624
    Quote Originally Posted by smurphy View Post
    I use a constsant cut in t-stat on walk in coolers all the time.Been able to maintain a 34 degree box temp with out any icing problems.
    I don't believe the johnson a19abc-24c is a constant cut-in control (your post #15) Correct me if I'm wrong. Now a Ranco a12-700 would be.

  8. #34
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    19,320
    JP turned me on to the Ranco A12-1506. It has worked very well on two occasions where there was a control failure.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  9. #35
    Join Date
    Mar 2002
    Location
    fort walton beach fl.
    Posts
    790
    Quote Originally Posted by VTP99 View Post
    I don't believe the johnson a19abc-24c is a constant cut-in control (your post #15) Correct me if I'm wrong. Now a Ranco a12-700 would be.
    I started reading this thread this morning till I got to my original posts. Then I realized this was from 2005, LOL. Anyways, I actually quit using this setup. I don't know why. Maybe at the time I was working for someone, and now I'm a owner. I do remember I had good results at the time. Mostly used it on walk in beer coolers. Nowadays, I just add a defrost timer, four defrosts a day, air defrost for 45 minutes.

    I use the Ranco A12-701 (constant cut in @41) for reach in coolers.
    http://acfwb.com/

    "The best preparation for good work tomorrow is to do good work today"

  10. #36
    Join Date
    Mar 2002
    Location
    fort walton beach fl.
    Posts
    790
    Double post
    http://acfwb.com/

    "The best preparation for good work tomorrow is to do good work today"

  11. #37
    Join Date
    Jan 2010
    Posts
    6,624
    Quote Originally Posted by smurphy View Post
    I started reading this thread this morning till I got to my original posts. Then I realized this was from 2005, LOL. Anyways, I actually quit using this setup. I don't know why. Maybe at the time I was working for someone, and now I'm a owner. I do remember I had good results at the time. Mostly used it on walk in beer coolers. Nowadays, I just add a defrost timer, four defrosts a day, air defrost for 45 minutes.

    I use the Ranco A12-701 (constant cut in @41) for reach in coolers.
    Wow !! 2005 how is it that these old post get revived ? I never even looked at the date. on the Ranco A12-701. I'll have to check out the Ranco A12-1506 that timebuilder mentioned.

  12. #38
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    19,320
    Quote Originally Posted by VTP99 View Post
    Wow !! 2005 how is it that these old post get revived ? I never even looked at the date. on the Ranco A12-701. I'll have to check out the Ranco A12-1506 that timebuilder mentioned.
    Here is a Ranco page that shows how the controls compare for temperature range.

    http://www.uni-line.com/images/docs/...erence-pg3.jpg
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  13. #39
    Join Date
    Jan 2010
    Posts
    6,624
    Quote Originally Posted by timebuilder View Post
    Here is a Ranco page that shows how the controls compare for temperature range.

    http://www.uni-line.com/images/docs/...erence-pg3.jpg
    Looks like jp's A12-1506 only varies slightly from the A12-700 by a few degrees cut-in. Does it do anything special ?

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