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  1. #1

    Need help for small heat/cool application

    I desperately need help trying to find a heat/cool solution for a small space. I have a stand-alone studio next to my house that is approx 160sf, brick contruction, located in Atlanta, GA. Currently it has no heating or cooling in it (just electricity and hot & cold water, and natural gas could be easily extended to it if that made sense to do). It has tons of cellulose insulation in the attic (about 2 feet deep) and fiberglass in the 2x4 walls and 2 normal-sized energy-efficient windows. Bascially, the heat/cool needs are very small (guessing 5-7k btu max). However, I'm having a difficult time trying to figure the best way to heat & cool the space. I have only 110 going to the building, so would like to stay with that (to go with 220 I would have to add a circuit and run about 120 feet of new wire). There is no ductwork and it is only one large room w/ a bathroom in the corner that isn't totally isolated from the rest of the space. I would only use this space occasionally as a work/hobby space, but could be any time of year. Summer temps in the 90's (and humid) and winter lows generally in the 30's and sometimes 20's.

    So given that information, I'm just not sure what type of heating and cooling system I should use. I thought maybe a through-the-window heat pump, but most seem to be sized too large for the space and I've heard they don't heat well when temps fall below maybe 45 degrees or so, but I like the idea of the efficeincy if it would work OK. Another option is through-the-window AC with a heat strip, but because of the lower heating btu's on those units (and what I've heard about them) it seems that it might not heat sufficiently using 110 power (was looking at an LG 7k BTU A/C w/ 3850 heating btu heat strip). I've also considered through-the-window AC only, plus wired in base board units for heat, but not sure how many feet of heating I'd need. I've also heard of ceiling fans that have heat built into them, but not sure how much heat that offers or how efficient. And of course, a small mini-split is an option. I like that idea the most, except the cost seems to be quite high for those units (well over $1,000 plus installation).

    Most of the time I wouldn't be heating/cooling this space to normal "comfort levels." I would mostly want to turn it on and make it comfortable when I plan on using it. However, I occasionally might want to let guests stay there when they visit, so would want them to be able to be comfortable too.

    Is there anything that you could recommend that might best meet those needs? I know there is probably no perfect solution, but I'd like to keep the cost somewhat reasonable, while making sure comfort is possible when needed, which won't be that often in general. Any suggestions you could offer would be much appreciated.

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,095
    If you only have a single 120 volt circuit. Your very limited in what you can do.

    Maybe a direct vent gas space heater. But then you still have the cooling problem.
    Even a 5,000 BTU window unit could dim your lights if its a long electric run from the panel box to this studio.
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  3. #3
    Join Date
    Feb 2003
    Posts
    1,996

    probably cheaper

    to upgrade the electric then to run a gas line out there. Maybe a PTAC, or any wall model would look better then using a window shaker.

  4. #4
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    If you have room in your electrical panel you should easily be able to get 220 in your studio with out any problems the only difference between 220 & 110 is the 220 use the black and white that become hot leads vs. 110 where only one usually blk is hot, and if your less then 40ft from the home using the same gauge wir that is already there is very possible. 160 sq ft. shouldn't be too difficult to heat and cool and I would go with some type of built in thru the wall unit I would think will work just fine for the usage your talking about, I also would look for something that will bring the temps up fairly quick but hold temps without cycling too often. A 6' or 8' electric base bd. should be able to heat that room size and a window shaker unit built in to your wall not a window and thru the wall should be ample to cool. I believe Carrier make several model mini heat pump type windo or wall units.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,095
    Reread his post. He said it would be about 120' to run a new line. Can't always run electric as the crow flies.
    By code a white insulated conduct must be recolor marked if used for a load carrying conductor.

    At 120', he'll have trouble using a 12 gauge wire for a 6 or 8' baseboard.

    If he contacts a smart electrician. He'll be told it needs to be a heavier 3 wire.
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  6. #6
    Join Date
    Sep 2007
    Location
    Panhandle WV
    Posts
    47
    whoa! WHOA!! hold it right there pardner.

    Suggesting exchanging the neutral for a second hot leg is WRONG. period.
    How will this provide for the existing 120V loads? Dont answer.

    The only safe, and I may add permissible way to provide 120V and 240V is
    to provide three wire with ground.

    To OP:
    If you need 240, and it would seem you do, have a competent electrician
    make the correct decisions based on anticipated electrical loads.
    Do it safe, do it right, and do it once.

  7. #7
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    You didn't say what you use the "Studio" for, but if the system being quiet is important, there are a number of 9000 btuh ductless split systems that run off a single 115v circuit.
    If more government is the answer, then it's a really stupid question.

  8. #8
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    I missed the 120' distance to the studio I was thinking it was right next to the home, my mistake !!! As for the wire with that distance you would need like 6 gauge 3 wire with a ground and would be expensive to wire either up in the air or buried !!!

  9. #9
    Join Date
    Jun 2008
    Location
    Surrey, BC, Canada
    Posts
    35
    I think you have answered most of your own questions. I would recommend running more power and possibly putting in a sub panel for future power requirements. Like anything else, this is an investment into your home. You can spend more money and put in the ductless split or go with a window unit. Better is often best over the long run.

  10. #10
    Thanks for all the great input everyone. It seems clear that I need to upgrade the electrical service to the studio, no matter what solution I go with. I was hoping I wouldn't have to do that, because of the additional expense. Unfortunately, my panel box is at one end of the house and the studio is at the other end of the house, over 100 feet away (it's one of those long rambling ranch houses). I was just remembering last time I had an electrician run 240 wire half that distance it cost a boatload of $$$, which is why I was trying to avoid it, and now copper is even more expensive. It would be at least 120 ft required, considering going around stuff, but at least I did put in a 6" under-ground tunnel under the court-yard slab that joins the two buildings when routing the new plumbing, so it'll be easy to string it under there.

    I think you guys have talked me out of the window unit also, but I don't want to cut a big rectancular 2 foot hole through the brick either, so it looks like I may need to go with the mini-split or maybe a ptac. Do ptacs require a huge opening thru the wall, or just a small "pipe" hole, like the mini-split?
    Everything else I've upgraded in the house I've tried to use high-quality, so I guess I shouldn't cut corners here. Appreciate the wise advice.

    Would you have a recommendation toward a particular brand of mini-split or ptac? Or a brand to stay away from? And size-wise, is my estimate of 5-7k btu fairly accurate? Thanks again for all your insight.

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,095
    Most PTACs are 16 x 42

    A ductless split, usually a 3" round hole in the wall.
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