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  1. #1
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    Nov 2019
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    Trane WSHP R22 Conversion to R407c

    I have a two ton Trane R22 water source heat pump that needs the evap coil replaced. The unit is 12 years old and the entire unit replacement cost is prohibitive because of the remote location. I am going to replace the evap coil, TXV, and compressor. The new compressor will have POE oil and I was going to switch to R407c during this process.

    My question is does it make more sense to just continue using R22 with the new POE oil for maximum capacity and then have the ability to drop in R407c in the future without having to change anything else? The difference in cost between R22 and R407c for this two ton system is not a concern.

  2. #2
    Join Date
    Aug 2002
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    Evap and compressor.

    Why did the compressor fail?

    Change the whole unit you’ve got a 12 year old water cooled condenser that will probably fail sooner then later!

  3. #3
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    Nov 2019
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    Thread Starter
    The issue is that where I am located in the Hawaiian Islands the cost of a new unit is around 3 times that on the mainland with a lead time of 3-4 months. Since the evap coil needs to be replaced now the idea was to go ahead and replace the txv and compressor while the system is apart and possibly switch to R407c. I was told by a Trane tech that the water cooled condensers were very reliable in a closed system with treated water. I can make all of these repairs and still be around a third of the cost of replacing the unit.

  4. #4
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    Sep 2002
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    What is the source of the water?

    Is it a field-loop? A well-loop? Or is it well water used directly?

    The discharge air temperature will trend somewhat cooler with R-407C than it did with R-22. The heating capacity will be reduced but the small amount (7 or 8%) will generally be overcome by longer run times.

    If the units are adequate to the connected heating and cooling loads with a 10-15% over-capacity - which is likely - the R-407C will be satisfactory.

    If I were doing this conversion I would want to give substantial thought to using an R-410 compressor and TXV with the new evaporator.

    All that being said: if the price of new R-22 is not a consideration to you - why even ask the question? R-22 runs well over POE.

    Whichever way you go - install an oversized suction line filter drier.


    PHM
    --------


    Quote Originally Posted by cdubs20 View Post
    I have a two ton Trane R22 water source heat pump that needs the evap coil replaced. The unit is 12 years old and the entire unit replacement cost is prohibitive because of the remote location. I am going to replace the evap coil, TXV, and compressor. The new compressor will have POE oil and I was going to switch to R407c during this process.

    My question is does it make more sense to just continue using R22 with the new POE oil for maximum capacity and then have the ability to drop in R407c in the future without having to change anything else? The difference in cost between R22 and R407c for this two ton system is not a concern.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #5
    Join Date
    May 2014
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    Personally, I would probably just replace what was bad, and stick with 22.

    But I doubt you would notice any capacity loss by switching to 407C.
    I do a triple evac with nitro to remove non condensables.

  6. #6
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    Thread Starter
    Sorry I left out a bit of info that may help it make sense. These little units are very tight to begin with and they are located in a coat closet. With the evap coil, txv, and blower removed the divider plate can be bent up for easy compressor access. Otherwise I feel it would be very hard to replace the compressor alone. This is the reason for proactively replacing the compressor at the same time as the coil. The water source is a closed loop with a cooling tower and treated water. The idea of switching the oil to POE but sticking with R22 for the best performance was a new concept to me. The discussion is always about changing the oil to change the refrigerant type but I like the idea of changing the oil now while convenient for a simple refrigerant change in the future if needed. Thanks for the help.

  7. #7
    Join Date
    May 2018
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    Elizabethtown, PA
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    Isn't the air temp in HI virtually always within 5-10 deg of the groundwater temp? I would not have expected WSHP's to be very common or practical there.

  8. #8
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    Aug 2002
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    Southold, NY
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    So your changing a perfectly good compressor?

    With POE make room for a suction filter.

  9. #9
    Join Date
    Sep 2002
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    Without severe abuse of some kind - a 12 year old compressor is in excellent condition. If it makes you feel better to change it - go ahead. But I doubt that I would.

    You can leave the existing compressor and it's mineral oil and use R-22 or R-407C. For R-407C You can add a few ounces of POE to the mineral oil or a few ounces of Supco 88 if you tend to worry a lot. I like adding Supco 88 in general. It's the Marvel Mystery Oil of refrigeration. <g>

    All that being said: if cost is not a factor - just install all new everything now and be done with it. <g>

    Is the new coil all aluminum?

    PHM
    -------



    Quote Originally Posted by cdubs20 View Post
    Sorry I left out a bit of info that may help it make sense. These little units are very tight to begin with and they are located in a coat closet. With the evap coil, txv, and blower removed the divider plate can be bent up for easy compressor access. Otherwise I feel it would be very hard to replace the compressor alone. This is the reason for proactively replacing the compressor at the same time as the coil. The water source is a closed loop with a cooling tower and treated water. The idea of switching the oil to POE but sticking with R22 for the best performance was a new concept to me. The discussion is always about changing the oil to change the refrigerant type but I like the idea of changing the oil now while convenient for a simple refrigerant change in the future if needed. Thanks for the help.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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