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  1. #1
    Join Date
    Jan 2007
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    maine
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    792

    freezer conversion

    hey guys was doing a pm at a new store today, they have a walk in with 2 condensing units and 1 evap per unit.. One of the units used to be a walk in freezer and was converted to a cooler.. they changed the gas and that looks to be it.. Forgot to check the txv for numbers.. Is converting a unit that ran r 502 to r 507 the way to go?? this unit seems way oversized for even the freezer application.. The unit has 1 3/8 in suction and 1/2 liquid line feeding the coil.. The coil wasnt re wired, so the fans shut off and heaters come on in defrost..

    Never done a change over like that and just seemed out of the ordinary to use the heaters and kill the fans.. Not sure how that pump is running and if the suction gas is keeping it cool enough or if this pump is running out side it envelope, and if 507 is a good change..

    condensing unit is a hussmann
    model-gcol0505rk
    serial-91g03428-639

    evap numbers i cant read

    compressor is copeland
    model-mra2-0500-tfc
    serial-96g76213

  2. #2
    Join Date
    Nov 2007
    Posts
    162
    What size box is it, how far is the cond. unit from evap. I would sure think sizing would be off since application has totally changed. R-507 is fine for the gas but you may have alot of other issues.

  3. #3
    Join Date
    Jan 2007
    Location
    maine
    Posts
    792
    unit is about 40 ft from evap.. the old freezer box is aprox 8 x 12 and cooler section is 8 x 25.. they left the wall in between the cooler and freezer and just removed the door... I see many problems that will arise from this thats why im trying to get some info before it all goes down LOL

  4. #4
    Join Date
    Sep 2005
    Location
    florida
    Posts
    5,514
    Quote Originally Posted by yotaman16 View Post
    hey guys was doing a pm at a new store today, they have a walk in with 2 condensing units and 1 evap per unit.. One of the units used to be a walk in freezer and was converted to a cooler.. they changed the gas and that looks to be it.. Forgot to check the txv for numbers.. Is converting a unit that ran r 502 to r 507 the way to go?? this unit seems way oversized for even the freezer application.. The unit has 1 3/8 in suction and 1/2 liquid line feeding the coil.. The coil wasnt re wired, so the fans shut off and heaters come on in defrost..

    Never done a change over like that and just seemed out of the ordinary to use the heaters and kill the fans.. Not sure how that pump is running and if the suction gas is keeping it cool enough or if this pump is running out side it envelope, and if 507 is a good change..

    condensing unit is a hussmann
    model-gcol0505rk
    serial-91g03428-639

    evap numbers i cant read

    compressor is copeland
    model-mra2-0500-tfc
    serial-96g76213
    You have said it. use to be a frz no evap rewire frz fans will shut down when
    in defrost.
    I love the smell of phosgene first thing in the morning:

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  5. #5
    Join Date
    Jan 2007
    Location
    maine
    Posts
    792
    Quote Originally Posted by crackertech View Post
    You have said it. use to be a frz no evap rewire frz fans will shut down when
    in defrost.
    Yea but is that the proper way to have the now cooler evap wired??

  6. #6
    Join Date
    Apr 2007
    Location
    Loris SC
    Posts
    208

    ?????

    Freezer, Electric defrost, timed controls, FAN, CYCLE and delay and defrost Termination


    Cooler???? Contioues FANS

  7. #7
    Join Date
    Dec 2007
    Posts
    50
    These types of jobs crack me up. There's a lot of re-engineering out there. Usually done by the business owner that thinks you can 'just change a thermostat' to make a freezer a cooler. Explain to the customer that equipment is designed for specific applications. Oil return is one of the biggest concerns when sizing equipment. Oh sure ...some re-engineered equipment may run for a while...just like a car will move ...as it falls off a cliff.
    My advice for what it's worth.. get the right equipment or run like hell from this job.

    Best o luck

  8. #8
    Join Date
    Jun 2005
    Location
    Las Vegas NV
    Posts
    1,152
    Quote Originally Posted by yotaman16 View Post
    Is converting a unit that ran r 502 to r 507 the way to go??

    condensing unit is a hussmann
    model-gcol0505rk
    serial-91g03428-639

    evap numbers i cant read

    compressor is copeland
    model-mra2-0500-tfc
    serial-96g76213
    yotaman,

    The Copeland MRA2-0500-TFC is rated for two, applications:
    Low temp R-502 28,400 BTUH @ -10 SST (approx)
    High temp R-12 35,600 BTUH @ +25 SST (approx)

    I'll assume the original low temp evap was rated around 30,000 BTUH and has 6 fans. If you raise the SST to +25 on this evap, it would be rated for about 33,800 BTUH.

    So, stay with a low pressure gas, R-12, R409, Hot-Shot etc. Change the TEV to a 2.8 ton balance port R-12 valve. The TD across the evap would be about 10.6 which is fine for a cooler.

    Do not convert to R-507. R507 is a high pressure gas such as R502 or R404A which in this case would be for low temp. Even if you were keeping this unit as a low temp R507 would not be recommended due to an oil change required to POE and this compressor is not rated for the higher pressures and temperatures that R507 produces versus R502 / R404A.

    I would disconnect all the electric defrost controls and wire the fan to run all the time, just like a cooler. You might leave the timer for off cycle defrost. Wire it to cycle the system on the pump down solenoid valve.

    This system converted to R-12 or an alternate would be good for a box about 20 x 24 x 8 (approx using quick selection)

    Powell

  9. #9
    Join Date
    Jan 2007
    Location
    maine
    Posts
    792
    Quote Originally Posted by powell View Post
    yotaman,

    The Copeland MRA2-0500-TFC is rated for two, applications:
    Low temp R-502 28,400 BTUH @ -10 SST (approx)
    High temp R-12 35,600 BTUH @ +25 SST (approx)

    I'll assume the original low temp evap was rated around 30,000 BTUH and has 6 fans. If you raise the SST to +25 on this evap, it would be rated for about 33,800 BTUH.

    So, stay with a low pressure gas, R-12, R409, Hot-Shot etc. Change the TEV to a 2.8 ton balance port R-12 valve. The TD across the evap would be about 10.6 which is fine for a cooler.

    Do not convert to R-507. R507 is a high pressure gas such as R502 or R404A which in this case would be for low temp. Even if you were keeping this unit as a low temp R507 would not be recommended due to an oil change required to POE and this compressor is not rated for the higher pressures and temperatures that R507 produces versus R502 / R404A.

    I would disconnect all the electric defrost controls and wire the fan to run all the time, just like a cooler. You might leave the timer for off cycle defrost. Wire it to cycle the system on the pump down solenoid valve.

    This system converted to R-12 or an alternate would be good for a box about 20 x 24 x 8 (approx using quick selection)

    Powell

    thanks powel.. The evap has 4 fans.. not sure of what they did before at this account but its got 507 in its now.. not sure if they actually did a oil change when doing this conversion.. The unit ran on R 502 before it was converted to a cooler... Its a hack job just from poking around for the short time i was doing the pm.. I just want to know the best way to have this unit running so when it ****s the bed i can do what i want.. These accounts r GREAT with letting me do what needs to be done and dont usually complain about any bill i put through.. So i wanna have all my ducks in a row when this system crashes and burns, so i can go in there and do all repairs that i need to and get this running the proper way.. My main concern is oil return as was stated earlier.. the line sets are 1/2 and 1 3/8 no traps, riser of 5 ft out of evap then 25 horizontal and 5 drop to compressor out side..

  10. #10
    Join Date
    Jun 2005
    Location
    Las Vegas NV
    Posts
    1,152
    Quote Originally Posted by yotaman16 View Post
    I just want to know the best way to have this unit running so when it ****s the bed i can do what i want.

    My main concern is oil return as was stated earlier.. the line sets are 1/2 and 1 3/8 no traps, riser of 5 ft out of evap then 25 horizontal and 5 drop to compressor out side..
    yotaman,

    If it's already been converted to R507 and that's all, then it's just a freezer with the temperature turned up. We've discussed this in other threads recently, it's not a good idea. If you don't want to make the change at this time to a low pressure gas, just leave it alone and it will destroy itself. Then you can replace the equipment.

    The line sizes are ok. If you want to add traps in the suction line that would be good, and slope the suction line toward the compressor. But, this may slow down the impending doom of the compressor that you are waiting for.
    Last edited by powell; 12-11-2007 at 11:17 PM.

  11. #11
    Join Date
    Jan 2007
    Location
    maine
    Posts
    792
    Quote Originally Posted by powell View Post
    yotaman,

    If it's already been converted to R507 and that's all, then it's just a freezer with the temperature turned up. We've discussed this in other threads recently, it's not a good idea. If you don't want to make the change at this time to a low pressure gas, just leave it alone and it will destory itself. Then you can replace the equipment.

    The line sizes are ok. If you want to add traps in suction line that would be good, and slope the suction line toward the compressor. But, this may slow down the impending doom of the compressor that you are waiting for.
    At this time i cant change anything but the first time it goes down that gas will be gone, ill put an r12 txv like u said in and charge with some 409a, repipe the dryer and glass the way it should be, and rewire the system and put a new ETC and get rid of that junk stat thats on the wall.. I wrote the unit up on the pm as a hack of a conversion, bad defrost clock and being low on gas.. Even tho they wont aprove fixing that stuff it will die soon as im sure that pump is running way out side its parameters with that gas in it, and im sure the superheat at the comp is through the roof.. And with the size u gave for that capacity that should cool the box without the other system in there and then i can just stage the stats

    However thanks a ton for the info cuase thats what i will do to the system when i get my first workorder on it.. Im not gonna leave a system all hacked up like that and put my name on it

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