1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)

Mini-Split heating/cooling units

Post in 'The Green Room' started by fossil, Aug 24, 2012.

  1. fossil

    fossil Accidental Moderator Staff Member

    Joined:
    Sep 30, 2007
    Messages:
    10,323
    Loc:
    Bend, OR
    I'm beginning to seriously consider this as a solution to the summer heat in both my house and my guest apartment. House has electric forced air furnace, which is very effective at heating, but no A/C. I could have A/C retroed into the existing system, but I think it would be very expensive, and I don't want to cool the whole house...just my bedroom. The apartment is in-wall electric heaters, and again, no A/C. Both spaces have a lot of westward-facing glass, much of it up high with no window covering at all. There are days in the summers here when both those spaces get really uncomfortably warm. The heat load on the room (it's a one-room apartment) is horrendous when the sun gets down to where it's beating directly in through those high windows. My bedroom in the house is similar. Gonna start, I think, by looking into the Mitsubishis...open to all suggestions. Thanks, Rick

    Helpful Sponsor Ads!





  2. fossil

    fossil Accidental Moderator Staff Member

    Joined:
    Sep 30, 2007
    Messages:
    10,323
    Loc:
    Bend, OR
    Pic of the west face of the building where the one-room guest apartment is (second floor). The offending windows are the high three. In mid-summer when the sun gets down to where it can blast right in through those windows, that room can get to be really way too hot to be comfortable, and then stay that way right up through an average bedtime. Not good. <> Over in the house, my bedroom is similarly configured and situated, and has the same problem. Rick

    garaj-mahal.jpg
  3. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    29,095
    Loc:
    Northern Virginia
    Got the same sun angle problems here fossil. But not as classy a house. So the 5,000 Btu window units from Target on closeout at $30 each have kept me from jumping on the mini-splits.

    But the heating side of the mini-splits have me thinking...
  4. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,711
    Loc:
    South Puget Sound, WA
    The first line of defense is to reduce the solar gain. That will make it an easier job to cool for the heat pump. Otherwise it's like trying to improve gas mileage with 500# of cement blocks in the trunk. Look into blinds, solar film, or other options.
    PapaDave likes this.
  5. fossil

    fossil Accidental Moderator Staff Member

    Joined:
    Sep 30, 2007
    Messages:
    10,323
    Loc:
    Bend, OR
    Yeah, BB, I don't have the right kind of windows in either application to mount a traditional window unit. Had one that I built right into my shop in Virginia, and it worked like a charm...but I just have no place for that solution here. In my case, heating's not really the problem (although these little guys might be competitive with what I'm running now)...the big deal for me is cooling, and really only during about 4 months out of the year ( and no appreciable humidity ever...nothing like NOVA!). The fact that these things don't care if you even have windows makes them very flexible so far as locating the two units. I'm liking it more and more the more I think about it. Rick
  6. fossil

    fossil Accidental Moderator Staff Member

    Joined:
    Sep 30, 2007
    Messages:
    10,323
    Loc:
    Bend, OR
    Yeah, BG, you're absolutely right. And I'll have to resume my work on that angle. After the huge remodel of the house, when we moved out of our apartment (having lived up there for ~1 yr) and back across the driveway (2009), I knew we needed to address that west-facing summertime heat load problem in both buildings. I was looking at films, screens, awnings, all those sorts of things, and talking with our window treatment/wood flooring guy about it. Well, then things happened (late 2010) to take my attention away from pretty much everything. I'm just now finding that I'm able to think mostly about today and tomorrow instead of always yesterday. Rest assured I'll somehow turn away all the nasty summer BTU's I can before I set the dogs loose on the ones that make it through my defenses. Rick
    PapaDave likes this.
  7. woodgeek

    woodgeek Minister of Fire

    Joined:
    Jan 27, 2008
    Messages:
    2,856
    Loc:
    SE PA
    As BG noted, solar film works great on E/W facing glass for just this problem, and any shape of window. Most cut visible light transmission by ~50%, but the human eye doesn't notice the change.
  8. ROVERT

    ROVERT Member

    Joined:
    Aug 7, 2012
    Messages:
    120
    Ductless units should work nicely for you. I don't have any experience with Mitsubishi units, but I imagine they are on par with the likes of LG and Sanyo (now Panasonic) which I've had good experiences with. I think they will be more than competitive with your current heat. I would say these will save you a considerable amount over straight electric heat. The fact that you want to install AC anyway means the cheaper heat is pure bonus.

    You should have them sized properly for the spaces they will condition. Many contractors tend not to run heating/cooling loads. They just size from experience and then add a little bit "to be on the safe side". This is partly the consumers fault because they don't understand how AC is supposed to work. When home owners complain about air conditioners running too long and not cooling down fast enough when they are actually properly sized, contractors are encouraged to oversize units.

    In a climate like we have here in the east, this means systems that do not effectively remove humidity. Around here we have lots of well insulated, 2000 sq ft houses with 3 1/2 and 4 ton heat pumps. They certainly keep the houses cool, but they don't keep them as comfortable as they should. Oversizing shouldn't be as much of a problem in a low humidity climate, but it is still best to have it sized properly for best efficiency.
  9. semipro

    semipro Minister of Fire

    Joined:
    Jan 12, 2009
    Messages:
    2,420
    Loc:
    SW Virginia
    Agreed on what ROVERT said about over-sizing systems. Also, looking for a contractor that uses "Manual J" or at least knows what it is would be a good start finding someone competent.
    I'm wondering how important cooling humidity control will be in Bend though If I recall right its very dry there.
  10. fossil

    fossil Accidental Moderator Staff Member

    Joined:
    Sep 30, 2007
    Messages:
    10,323
    Loc:
    Bend, OR
    It's very dry here (high desert country)...humidity control is not one of my aims. Having lived in Northern Virginia for 12 years, I do know exactly what you're talking about (aside from the fact that I'm a Mechanical Engineer). Cooling is the primary objective, and possibly taking over the winter heating duties from the in-wall mounted electrics up in the apartment. The contractor who built the building shown above in 2007 and remodeled our home in 2008 is a good friend and a long time Bend resident. When I tell him what I'm considering doing, he'll put me in touch with exactly whoever I need to talk to here. He knows everyone anyone needs to know in the building trades around here.

    First I'm going to look into the solar film, plus maybe the retractable awning for the west deck off the house that I was looking at in early 2010. Thanks much for sharing your knowledge & experience, folks...I really appreciate it. Rick
  11. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    29,095
    Loc:
    Northern Virginia
    The mini-splits have had my attention for a couple of years. Replacing the old heat pump isn't attractive because of the duct work loses and the fact that since it isn't zoned to keep the upstairs cool you are paying to freeze to death down stairs because our roof gets full sun while the trees shade the downstairs. What I could never figure out is how many units and where in a typical center hall colonial house. Nine rooms, not counting three bathrooms, with only the kitchen and family room not separated by walls and narrow doorways for air movement. Not many problems setting up a natural convection for heating with wood but a nightmare for figuring out how many and where with mini-splits for cooling. Especially upstairs for the four bedrooms.
  12. fossil

    fossil Accidental Moderator Staff Member

    Joined:
    Sep 30, 2007
    Messages:
    10,323
    Loc:
    Bend, OR
    Yeah, just like my house back there. We had central A/C which was built in with a NG heater. Can't imagine how I would have managed that with little separate units. Out here it's a much more straightforward deal. There are only two rooms I care about...my bedroom in the house, and the apartment in the other building. I can obviously live without doing anything about it, as I've been here 5 years and I'm still breathing. Back in NOVA, I'd have long since been dead by now. ;lol
  13. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    29,095
    Loc:
    Northern Virginia
    I'm still cussing the guy that talked me into transferring here on the promise of it being a 18 to 24 month deal 30 years ago and then moving me back to Texas. He died six months after the move. Yeah, I know he got the worst end of the deal but still...
  14. Hogwildz

    Hogwildz Minister of Fire

    Joined:
    Nov 3, 2006
    Messages:
    7,119
    Loc:
    Next to nuke plant Berwick, PA.
    BB, the mini splits can range from one outside unit for one inside head, to one outside unit to 4 inside heads, and any combination in between. May be just what you are looking for.
    I have ductboard with forced air. And the tape is coming apart on the ducting, also flex branches. The whole system is trash as far as I am concerned. Seriously thinking of mini splits here too. The addition has no basement or ducting, so that will be minis all the way. Might as well get the ones with the heating capabilities also.
    I just recently stumbled on the fact that Home Depot sells mini splits now.

    Prolly better seer ratings out there but here is a link to HD's stuff:
    http://www.homedepot.com/Building-M...ENT_ID&langId=-1&storeId=10051&searchNav=true
  15. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,711
    Loc:
    South Puget Sound, WA
    Haven't heard of those HD brands. Are they out of China?
  16. peakbagger

    peakbagger Minister of Fire

    Joined:
    Jul 11, 2008
    Messages:
    1,722
    Loc:
    Northern NH
    One thing to keep in mind with Mini Splits in areas with snow is that they dont deal well with snow dropping off a roof or being left full of snow all winter. I have mine mounted on a shelf up on the ground ont he back of my house with a removable pitched roof over the unit. The back roof of the house is a 12/12 pitch and when the snow does let loose, it could trash the outdor unit. I have had a few of these events since the unit went in and the add on roof has protected it.
  17. velvetfoot

    velvetfoot Minister of Fire

    Joined:
    Dec 5, 2005
    Messages:
    6,965
    Loc:
    Sand Lake, NY
    Can a homeowner install one himself? I've seen videos on the web and it doesn't seem that hard. The lines are precharged, or something, and all you have to do is open a valve? Thing is, could you get a service technician to come over to fix things if the install went bad (like a leak), or something breaks in the future? I can see not having a warranty if a professional doesn't install it, but it might be worth a shot to save some money.
  18. ROVERT

    ROVERT Member

    Joined:
    Aug 7, 2012
    Messages:
    120
    The condensing unit is typically pre-charged for up to 25 feet of lineset, but just opening a valve is not all there is to it. You need to evacuate the lines/evap unit prior to charging the system. You also technically need a gauge set to check the system and EPA cert.

    A homeowner could do it, just not correctly or legally without certification and some pricey equipment.
  19. Jags

    Jags Moderate Moderator Staff Member

    Joined:
    Aug 2, 2006
    Messages:
    15,264
    Loc:
    Northern IL
    I am a bit confused about the heating side of the mini-splits. In Rick's case he is using electric wall heaters (at 100% efficient ratings). What tech on the mini-splits, which I assume are electric - will allow for cheaper heating?
  20. ROVERT

    ROVERT Member

    Joined:
    Aug 7, 2012
    Messages:
    120
    It's a heat pump. Down to a certain temperature, depending on the equipment/system, an air to air heat pump is more energy efficient than resistance electric. If it weren't, no one would ever bother with heat pumps, they would just use electric strip heat in the air handler. Typically heat pumps lose their effectiveness in the 25-35 deg ambient temperature range, but newer equipment is improving upon this.
  21. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,711
    Loc:
    South Puget Sound, WA
    It's an air conditioner working in reverse. The unit in heatpump mode extracts heat from the outside air and transfers it via refrigerant to the indoor exchanger. Modern inverter scroll compressors have really improved this technology. It is not uncommon for the best of these units to work fairly well below 10::F. A couple winters ago I visited an old farmhouse that was being heated by a Fujitsu mini-split. It was 14::Foutside and the house was toasty warm.
  22. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,711
    Loc:
    South Puget Sound, WA
    Redirected to the green room with a permanent link to the DIY forum.
  23. Jags

    Jags Moderate Moderator Staff Member

    Joined:
    Aug 2, 2006
    Messages:
    15,264
    Loc:
    Northern IL
    Got it.
  24. Highbeam

    Highbeam Minister of Fire

    Joined:
    Dec 28, 2006
    Messages:
    9,440
    Loc:
    base of Mt. Rainier on the wet side, WA
    Resistance heat is always 100% efficient. Heat pumps are often over 300% efficient. They actually deliver more heat to the space than you provide the unit because the heat pump uses your energy input to extract heat from the air. That's also why they don't work as well in low temps because there isn't much heat to be squeezed out of 2 degree air.

    I'm a fan of minisplits. Great replacement for baseboard heaters since you already have the dedicated 220 volt circuit. Unfortuantely the inside unit looks like something you would see in an RV or a motel room wall heater. It is a challenge to make the indoor unit look acceptable.

    Sounds like a BK eh? Ugly but the ultimate in utility.
    pen likes this.
  25. backpack09

    backpack09 Minister of Fire

    Joined:
    Sep 10, 2007
    Messages:
    554
    Loc:
    Rochester, Mass

Share This Page