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  1. #1

    Heat pump application question

    Hello: I am new to the forum and have a question I hope someone might be able to answer. I have a well insulated 20ft by 22ft building in which I wish to store case goods (wine). I would like to find a heat pump with a high SEER (to work at low outdoor temperatures) that would keep the building about 50F in the winter and in the high 50's during the summer. All the systems I look at will only cool to about 62-64F and most don't have a low winter temperature setting. Is there something in the market that would allow me to do what I need without going to separate heating and cooling systems? It seems to me that this must be a possible configuration to achieve with a heat pump, but that there is not enough demand in the market?
    Thanks for you help.

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    34,189
    Air conditioning equipment is for keeping the space in temps a body would like. Keeping below the mid 60s would freeze the evaporator coil. You'd need refrigeration equipment designed for space temps colder.

  3. #3

    Another question

    I have another question. If what you say is true, BaldLoonie, why do several manufacturers offer through the wall heat pump air conditioners that will cool to 57F in the 12-15,000 btu range? (I'm looking for 24,000 btu). Also, don't several manufacturers offer heat pumps for cooling electronic/computer control rooms that are generating a lot of heat, and go lower than the usual 62-64F range?

  4. #4
    Join Date
    Jan 2008
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    Dallas ,Texas
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    Quote Originally Posted by baconfry View Post
    I have another question. If what you say is true, BaldLoonie, why do several manufacturers offer through the wall heat pump air conditioners that will cool to 57F in the 12-15,000 btu range? (I'm looking for 24,000 btu). Also, don't several manufacturers offer heat pumps for cooling electronic/computer control rooms that are generating a lot of heat, and go lower than the usual 62-64F range?
    If I were you I would definately go with the equipment that you have been researching and let us know how long it lasts?
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  5. #5
    Join Date
    Mar 2010
    Location
    Va.
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    180
    You can use a heatpump if it's equiped with hot gasbypass and low ambient controls. Serveral of my customers are beer distrabution centers and they both use refrigeration equipment to cool the space. Why are you looking at using heatpumps over refrigeration equipment?

  6. #6
    Phiser, thank you for your information, I appreciate it. I was hoping to use a heat pump to both heat and cool with one unit. With a refridgeration unit (which I can do) I need a separate heating system, right? I can do this too, but I was trying to keep it simpler and less expensive. How difficult/expensive is it to install a gas by-pass and low ambient controls? Or would that just be chasing good money after a bad idea?

  7. #7
    Join Date
    May 2002
    Location
    Madison, Wisconsin
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    430
    Quote Originally Posted by baconfry View Post
    Hello: I am new to the forum and have a question I hope someone might be able to answer. I have a well insulated 20ft by 22ft building in which I wish to store case goods (wine). I would like to find a heat pump with a high SEER (to work at low outdoor temperatures) that would keep the building about 50F in the winter and in the high 50's during the summer. All the systems I look at will only cool to about 62-64F and most don't have a low winter temperature setting. <stuff deleted>
    Thanks for you help.
    I don't believe you let us know whether you are a contractor interested in doing this installation or are looking for equipment and someone to install it. You also don't say anything about what sort of design outdoor ambient conditions it will have to handle.

    It sounds like your problem is that you want something in a nice little ready-made package that is basically a custom installation. You're right that the market [probably] does not make units that do this in their standard form. Controls would have to be subverted, or custom controls would have to be installed.

    Typical comfort cooling equipment runs, say, a 40* evaporator to get 70* space temp with 75* return air. You want 57* space temp. Sliding the evaporator temp down the same amount gets you a 27* evaporator - which means you will make ice. So you have to provide for a defrost cycle of some sort. Or make sure the air is pretty damn dry. [Are you in Arizona?]

    Typically, medium temp refrigeration is designed so that the compressor off-cycle is long enough for the space air to melt any ice that's on the coil. The space air is chilly in this case - so that might take a while. Among other things, this means you need a unit that has more cooling capacity than you'd probably expect. And that your building envelope had better perform as described ... or the off-cycles will be too short.

    A good refrigeration mechanic could install medium-temp refrigeration and configure it as a heat pump. Don't expect it to be cheap.

    I can also imagine a couple of ways to subvert a standard heat pump to work. But you would have to kiss your new-equipment warranty goodbye ... and/or possibly spend some additional money to install low-temp humidity control.

    Low temp humidity control is a problem for the very same reason as above. Your evaporator will be cold enough to make ice, and you or the equipment will have to provide some sort of defrost cycle. Low temp dehumidification can hog a lot of energy if not done correctly - and ready made equipment that does it well is priced accordingly. A standard basement dehumidifier *will not* do the job.

    In addition to all of the above ... if you live in a cold climate, you may need outdoor ambient temp controls, and/or back-up heat when it gets too cold outdoors.

    This is why off-the-shelf, unitary equipment won't likely do the trick.
    Last edited by fixitman; 11-12-2010 at 03:17 PM. Reason: clarification
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  8. #8
    Fixitman:

    Thanks for your lengthy reply, it helps. I have extensive construction experience but am not an HVAC professional. I will have one install whatever will work. I am trying to get information to make an informed decision and to ask the right questions of the HVAC person. And I have been puzzled (or at least I was before your response) about why a system would be difficult to design. Lowest outdoor temperature in our area (Pacific Northwest) is about 15-17F, but humidity is very high. I have a professional dehumidifier that would easily do the space equipped with a humidistat. I would be willing to forego a warranty if a system could be set up that really would work. It sounds like the best thing is to install a gas heating system with separate controls for the winter and a refridgeration unit for the summer. If you (or anyone else reading this thread) have any other ideas pass them along; and thanks again.

  9. #9
    Join Date
    Nov 2010
    Location
    Maryland
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    If you live in a cool enough climate , why not install a package unit with an economizer to bring in outside air ? With that small of a room should be no problem maintaining a 55 deg discharge air with economzer. More expensive start up cost versus a residential split system but will save more money in the long haul. Not sure but isn't wine humidity sensitive? If so , you'd have to add a humidifier to the equasion. Or just keep it underground , that is where the term "wine cellar" came from.

  10. #10
    Join Date
    May 2002
    Location
    Madison, Wisconsin
    Posts
    430
    Quote Originally Posted by normally_closed View Post
    <stuff deleted> ... Not sure but isn't wine humidity sensitive? If so , you'd have to add a humidifier to the equasion. Or just keep it underground , that is where the term "wine cellar" came from.
    The wine is presumably in glass bottles - not known to be moisture permeable. The wine that's in the Gore-Tex (R) bottles might be a problem ... :^/

    The moisture might also cause problems for the corrugated cardboard of the cases, if the humidity is chronically too high. And the labels on the bottles. Let me know when the "Ugly Case SALE" takes place. :^]
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  11. #11
    Join Date
    Apr 2004
    Location
    Rossville, GA
    Posts
    104
    they make wine coolers for this application.They are typically split system installation. I worked on some years ago that were called breeze air out of california. Good luck

  12. #12
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    Feb 2007
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    milford ct
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    161
    breeze airs are pos
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