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  1. #1
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    Masterbilt W/I Freezer

    I don't have model or serial number handy at the moment, but I have a problem child at a monthly PM customer's location. A Masterbilt W/I freezer with the electronic control (Master Controller?) simular to Heatcraft's Beacon II system.

    The top 1/3 of the evaporator frosts up WAY before the bottom 2/3s of the coil does. HEAVY. Within an hour of operating from being a frost free coil (thanks to MY de-icing efforts), that area will look like a freezer coil that's looking like an entire, typical, normally functioning freezer coil's time to enter into a defrost mode.

    It frosts up in a very distinctive formation. You can draw a straight line between the area of the coil that DOES frost and where it hasn't yet. You can virtually lay a straight edge along the frostline of the entire length of the four-fan evap coil (8 ft long maybe).


    On my next monthly visit, the backside's ice has grown to hug the ceiling.
    I return and it looks like this:
     


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    I called Masterbilt several times. A year ago or so they suggested redirecting the EEV for more uniformed distribution of refrigerant (!?). Attempted that by fiddling with it like bending a TXV around, using a calibrated eyeball...ya know. Another suggestion was to check the location of the termination sensor and relocate it if necessary. Did that.

    The last call I made they suggested that, in my DE-ICING efforts (with the defrost heaters and my water) the resulting STEAM...or ANY moisture for that matter entering the space, sends that moisture WHERE? YUP! UP! To the ceiling. Where's my ice formation? NEAR THE CEILING! With that, he suggested I check and adjust the termination setting in the controller. Although I thought I'd done that already awhile back, I didn't get that far because I encountered a frozen condensate drain line I need to go fix (RAYCHEM is my friend. Never had to replace one of those).

    So...thus far, every few months when I think it's time, when I'm doing my monthly PM visit and I had let it pass last month, I spend a few hours removing fanblades, de-icing there. Then, go to the back of the coils and contrive some means to capture these big ole logs of ice as they fall from the ceiling so they don't smash to the ground in a jillion little pieces.

    This is getting old.

    What's happening isn't right. Defrost is NOT the problem. There's something not right in those runs of refrigerant through the coils. The refrigerant isn't distributing properly. I have not opened the system to explore it.

    Could the distributor be the problem? An error in manufacturing? Some errant blob of Silflos...uh -FOS in there? If so, is there something I can try that's a much more expedient method besides replacing the DISTRIBUTOR head? I've heard and read of the horror stories in doing THAT!
     
     
     
     


    "You never know what others don't know." -

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  2. #2
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    What make is that evaporator ? How many distributor lines and how do they feed ? Is it a sweat or sae connection ? If sae pump down and open up to check to make sure there is a nozzle in there. Can also do a visual with nozzle removed to check feeds. Take a copper wire and clear each feed line from inside the distributor.

  3. #3
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    did you check the controller settings? The EEV can be changed to r22 or 404....other settings could affect performance. Here is the manual:
    Last edited by pdrake65; 10-21-2010 at 04:21 PM.

  4. #4
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    Thread Starter
    It's R404A. Thanks for the manual, by the way.

    Some time back I DID go through, check and change the programming parameters with this Masterbilt tech on the phone. On that occasion, my cutting power to the MAC8 ended up erasing some of the programming so had to set it up again. Given the original issues for my doing that, he had me taylor the settings for a more thorough defrost (now that I think about it). The ice problem had occurred before and after that.

    VT, my lead tech had suggested the same thing about the nozzle to me over the phone last month. I don't know why Masterbilt didn't suggest that. I didn't mention it to them yet.

    Before I do ANYTHING, I gotta fix the condensate line freeze-up first so I can commence to de-icing the coils. Ice growth also forms to encapsulate the section at both ends of the coil - especially the EEV and distribution tubes. Last visit that area was a solid block of ice.

    I have yet to actually do a dedicated service call on this thing. My PM requires my giving attention to their entire kitchen and takes all day. The manager plays tight-fisted and resistant to a dedicated service call bill for an ice problem if the freezer is working properly for him and meets his needs. Took them a week and half to approve my estimate to fix the condensate line. Approved nonetheless. I guess they don't like "ice skating" to get something out of the freezer. I hoping I get to that today.


    "You never know what others don't know." -

    If I can't laugh at myself...then I'll laugh at YOU! -

  5. #5
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    Did you by chance get any pressure readings? I see that the suction line is well frosted all the way up....possibly to the compressor? I had a mac8 unit doing something similar to this due to a low charge. Store didn't notice an issue until warm weather hit. i'm assuming that the area where the EEV is located is a big ball of ice?

  6. #6
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    It looks like the evaporator is starving, could be low on freon, could be a bad EEV, could be a dirty condensor causing low capacity, could be a bad suction line thermistor giving bad superheat readings. Check the sight glass first. The McD's that I work for would not put up with ice hanging from the ceiling of their walkin. That is some kind of a violation with the corp standards I'm sure.
    We do it nice cause we do it twice!

  7. #7
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    Any update on this??

  8. #8
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    Thread Starter
    Quote Originally Posted by pdrake65 View Post
    Any update on this??
    Haven't been back yet. Schedule's been too heavy with other's crisises. I'm scheduled to return tomorrow to construct a 12' section of a properly functioning condensate drain line. That's gonna be messy. With new Raychem heat tape and Armaflex, they'll never have that problem again.

    THEN I can de-ice the coils and proceed. Great suggestions here I will take with me to consider.

    A bit more on the history:
    1. This problem has existed for the two years that I've been visiting the place and isn't seasonal (summer vs winter).
    2. I don't think the store manager ever sees the ice until I take him back behind the evaporator to show him. Since his product is still frozen, I don't think he's concerned.
    3. It's a 404A system; the sight glass has always shown clear once in cycle.
    4. I've never put my gages to it for pressures, primarily due to the sightglass indication.
    5. Again, after I experienced that inadvertent "erasure of the programming" about a year ago, I did a walk-though of the controller's settings and readings with a pretty savvy Masterbilt tech on the phone. He had me tweak a few settings with the ice buildup problem in mind, but otherwise the readings were as he expected.

    I'm gonna start from there though after I de-ice it. Connect the gages and thermometer, take readings, then proceed methodically. Will have that manual with me to check settings, compare it's sensor readings to my gage and line temp readings, etc.

    I hope it IS something other than the distributor head or nozzle. I have a suspicion though that THAT'S the problem and probably has done this since it was first fired up after installation about three years ago. I HOPE I everything is flare connecte instead of brazed...I don't know yet though.

    I appreciate everyone's help and will update with what I find out.


    "You never know what others don't know." -

    If I can't laugh at myself...then I'll laugh at YOU! -

  9. #9
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    MasterBilt Evap Issue

    I'm new here, and if my two cents isn't welcome, please say so. If you're suction line is frozen (and appears it is) and you have a uniform frost pattern on half the evap (and it appears you do), and you have proper sub-cooling and a full sight glass, I would be after the distributor most definitely. If you're distributor tubes are clear, then that only leaves your EEV, but if you have distributor tubes that consistently don't feed, then it's almost got to be a distributor or orifice issue. If the problem didn't exist when the unit was installed, and it does now, it stands to reason something is plugging your distributor up.

  10. #10
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    Quote Originally Posted by zsmillie View Post
    I'm new here, and if my two cents isn't welcome, please say so. If you're suction line is frozen (and appears it is) and you have a uniform frost pattern on half the evap (and it appears you do), and you have proper sub-cooling and a full sight glass, I would be after the distributor most definitely. If you're distributor tubes are clear, then that only leaves your EEV, but if you have distributor tubes that consistently don't feed, then it's almost got to be a distributor or orifice issue. If the problem didn't exist when the unit was installed, and it does now, it stands to reason something is plugging your distributor up.
    That is probably what this issue is coming down to. If you noticed ,we have NO pressure or temp readings to come to this conclusion just yet. Super-heat or sub-cooling has not yet been checked. Stay tuned........

  11. #11
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    We need more info.
    I love the smell of phosgene first thing in the morning:

    To apply for professional membership click here


    Educational forums are open.

    If you would like to submit a link or an article or other related info to the EF. click here

  12. #12
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    Quote Originally Posted by crackertech View Post
    We need more info.
    Yea..like how the distributor circuit is layed out would be great ! 1 more piece to the puzzel please.

  13. #13
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    Quote Originally Posted by pdrake65 View Post
    That is probably what this issue is coming down to. If you noticed ,we have NO pressure or temp readings to come to this conclusion just yet. Super-heat or sub-cooling has not yet been checked. Stay tuned........
    Got a little ahead of the game there....Sorry.
    If You Can't Do The Time.....

    "Life's tough. It's even tougher if you're stupid!" - John Wayne

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