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  1. #14
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,389
    Quote Originally Posted by EugeneTheJeep View Post
    Infiltration and door open usually freezes the coldest part in the box first, the coil, fans wont frost up with no air flow through the coil, frost around the fans means humid air went through the colder coil, or the length of defrost caused vaporization and the vapor went to the next coldest spot near the coil and condensed there?
    I think while it's true that the moist air that goes through the coil will tend to cause frost buildup on that coil, there's also a lot of the air which bypasses the coil through the gap under the coil in the drain pan area. That moisture-laden air will deposit frost on and around the fans and fan guards. The coil frost buildup will usually clear up during the next defrost, but not necessarily so for the rest of it.

  2. #15
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    1,938
    Quote Originally Posted by icemeister View Post
    I think while it's true that the moist air that goes through the coil will tend to cause frost buildup on that coil, there's also a lot of the air which bypasses the coil through the gap under the coil in the drain pan area. That moisture-laden air will deposit frost on and around the fans and fan guards. The coil frost buildup will usually clear up during the next defrost, but not necessarily so for the rest of it.
    I guess that can happen too, but the OP really just needs to check for infiltration and go watch a defrost and see if it terminates on termination, or straight time, and he can check the pan as you suggest, then he can go to the door open problem. The door open problem is usually pretty obvious at least for me the first few minutes on the job watching the employees, and that also leads to a high temperature problem. I have had door open all the time customers where I had to put a pin in every cycle frequency on the Paragon 8145-20 just to keep the coil clear and the ice cream hard, and it worked!

  3. #16
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,638
    Door problems are easy to spot. The untrapped drain which terminates in an unconditioned space or outside is easily overlooked as is the conduit or sealtite run from the condenser to the evaporator bringing in outside air.
    Officially, Down for the count

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  4. #17
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    1,938
    Quote Originally Posted by 2sac View Post
    Door problems are easy to spot. The untrapped drain which terminates in an unconditioned space or outside is easily overlooked as is the conduit or sealtite run from the condenser to the evaporator bringing in outside air.
    That makes good sense too, that would bring the vapor right past the coil.

  5. #18
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Technically speeking its all infiltration of some kind. The frost is a symptom as is the location of the frost or ice. The frost is a symptom of infiltration, which will never be stopped. The location is a symptom of long defrost and fans not delaying after defrost. IMHO.

  6. #19
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    453
    I don't know bout the rest of you guys but my first check involves an amp meter. This type of issue is why I preach electrical skills are mandatory for a tech in the field running service calls.

    Probably the reason why he is seeing uneven ice is due to long defrost times with one or more open heating elements, temps in box rising above 32F and some air defrost going on.

  7. #20
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    1,938
    I usually mark the amps near the timer on every install just for that reason, you have the actual draw when new.

  8. #21
    Join Date
    Jun 2012
    Location
    Tenn
    Posts
    139
    Check the fan delay, but like Ryan and 2sac mentioned, moist air could be entering. Perhaps the door is open all day. Maybe there is an air leak. To be honest, even if you replace the delay, I would check the gaskets, and any thru areas for possible leaks. It's been my experience that when lots of ice builds up on the evap, there is lots of air entering the box. Often it is the resturant crew leaving the door open especially overnight.

  9. #22
    Join Date
    Jul 2011
    Location
    St. Louis
    Posts
    121
    Lot's of guidance here on the source of the moisture. Door openings, leaky seals, etc. but moisture will always get into the box. The solution is to get good, complete defrosts, at the proper time and for the proper duration. Modern controllers with reactive (demand) defrosts will take care of the proper trigger to start a defrost. The next critical factor is when to terminate. If any ice is left on the coil when defrosts terminate, it will build over time. Since the coldest part of the coil is on the fan side, that is where the ice will build and can eventually hit the fans. Once that happens the blades may go out of balance and kill the fan motor or vibrate pieces off the coil.
    Aside from the reactive defrost, placing the defrost terminator IN the coil at the coldest point or where the ice goes away last. Preferably actually in the fins, if defrost continues until that spot is clear, then the entire coil will stay clear and the fans won't get ice damage.
    In an infinite universe, not only are all things possible, all things are necessary

  10. #23
    Join Date
    Mar 2013
    Location
    Central IL
    Posts
    103
    I 've seen this alot at college kitchen were they don't like to close door when doing envitory.........you can't fix stupid.

  11. #24
    Join Date
    Aug 2010
    Location
    Northern Cali
    Posts
    72
    I recently ran into a problem where the customers walk in freezer was having a similar problem.......snow everywhere ....frost on the product ..frost on the ceiling ......The walk in is located in a non air conditioned warehouse.....When the product is delivered they leave the w/i door open while they are stocking. So naturally I blamed it on them leaving the door open for so long.....and after checking everything , defrost clock, heaters, fan delay....all ok. Then one day I was there for something else and I figured while I was there I would take a look at the w/i . I happened to go in right when the the box satisfied on temp. and evap fans turned off. Who ever installed the box . Wired it up so that the evap fans shut off when box makes temp.....and when it kicks on it just makes it mist for just second and of course the mist turns to frost instantly.

  12. #25
    Join Date
    Dec 2012
    Location
    Dodge City Kansas
    Posts
    13
    what size box you have here?

    If you're working on a walk-in that's going to be different than a reach-in or regular freezer.

    If this is a walk-in;
    Plan on spending enough time here and let the unit go through a defrost cycle and see how it goes.

    That's going to give you enough information to see if the defrost needs adjusted or not.

    In winter it might not be so long and need to be lowered. Is the box outside? are you in San Gabriel?

    I'd bet the evap fans aren't shutting off during defrost.

    Is that box situated inside a building? or outside?

    and when you mention "a hole on a evaporator where the fan blades are," how many evap fans?

    It's possible you need to post more info.

  13. #26
    Join Date
    Jan 2007
    Location
    maine
    Posts
    790
    Did ou make sure the drain is trapped

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