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  1. #1
    I have a section of my basement (all below grade, not a walkout) I will be finishing into a home theater. When finished, it will be 19 by 14 with 7 foot ceilings. It will be well insulated.

    I used HVAC-calc (great program!) to figure a heat gain of 6,552 btuh and a heat loss of 2,738 btuh. The room will have seating for 8 but many times only 2-4 people will be using it. I figured my heat gain using the worst-case scenario, 8 people in the room. This heat gain also figures in a ceiling mounted projector.

    I have been looking at using a mini-split to provide heating and cooling. I have looked at two models in the Mitsubishi line:

    Model MSH09TW with 8,880 btuh cooling and 10,500 btuh for heating

    Model MSZ09UN with 8,880 btuh cooling and 12,300 btuh for heating

    This second unit uses Inverter technology to adjust the compressor speed. By varying the compressor speed it can output a variable amount of cooling (2,600-9,700 btuh) and a variable amount of heating (2,300-15,700 btuh). According to the specs it is quieter than the first unit as well.

    I have three questions I am hoping someone can help me with:

    1. I live outside of Rochester, NY. We can get short stretches of 2 or 3 days when the temperature never goes above the teens. There are 6 or 8 nights during the winter when the temperature goes into the single digits. Much of the winter it is in the 20s or 30s. Can the heat pump on this unit keep up with this type of cold? As far as I can discern, these two units are not available with supplemental heat strips.

    2. The unit with the inverter is about $400 more than the one without. Is the unit with the inverter worth paying extra for? It seems like it might be for three reasons it can put out a variable amount of heating and cooling, it is more energy efficient, and it is quieter (important for a home theater). I have not seen any other manufacturer (Sanyo, Samsung, Fujitsu, Daiken, York, etc.) that uses Inverter technology on their mini-splits.

    3. Am I better off purchasing a cooling only mini-split and installing electric baseboard heating? In other words, split the heat and air conditioning into two separate sources.


  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
    Probably 3. Check the output figures of these minis. Very little heating once they drop below freezing if they run at all. Most have little or no backup heat. If you do get a heat pump, you'll want baseboard or some other backup method in a cold climate.

  3. #3
    Can a mini-split be set to provide heat down to a certain temperature, say 40 degrees, and then turn off?

    I could install a mini-split with a heat pump and also a strip of electric baseboard heat. There are several months during the year in Rochester when the temps are in the 40s, 50s, and 60s. The heat pump would provide heat to my home theater in this case. As soon as the temp goes below 40, the heat pump turns off and the electric baseboard kicks in.

  4. #4
    Join Date
    Feb 2003
    They also have a 15K HP unit that has electric strip backup.

  5. #5
    I have scoured the Mistubishi site for this 15K Heat Pump with electric strip backup and cannot find it. Do you have a model number or a link?

  6. #6
    Join Date
    Feb 2003

  7. #7
    Thanks for the link. Wouldn't this unit be overkill for my space given the heat loss and heat gain numbers I show above? This unit does not have inverter technology so I am guessing in my space it would short cycle or just turn on, blow out a large quantity of heat or cooling and turn off after a short period of time

  8. #8
    Join Date
    Feb 2003
    You're probably right. The warm air might be nice to quickly heat up the room if you only want to heat when using the room. Electric baseboard will need to kept on to hold a min temp. I'd go cool only, the mini's do nothing for you in the middle of winter. Why make the condesnser fight to make heat when it's covered with snow. What heats the house now? If you had hydronic heat, I'd just add a zone of BB or do radiant. There's also electric matting for used under an uncarpeted floor.

  9. #9
    Join Date
    Nov 2005
    New York

    Wink Daikin

    The Daikin VRV Heatpump system can operate @ -5 deg F. This might be your best bet.

  10. #10
    I have a forced air gas furnace. Already looked into zoning and that is not a good fit. I will probably end up going the baseboard electric plus cooling only mini split route. Thanks for the help


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