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Small Cabin Forum / Cabin Construction / Mini-split system
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FishPCreek
Member
# Posted: 28 Aug 2016 17:57
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I have seen some discussion on AC using mini-splits, and wondered if anyone in central PA is using one, and how successful it is. I am interested also in the heating aspect to take the edge off the cabin before the woodstove really gets things going - like on some 20-degree arrivals in winter! I have three small wall-pack heaters and they help, but not as much as i would have thought. Thanks for any experiences shared.

Shadyacres
Member
# Posted: 28 Aug 2016 19:28
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I've used a sanyo khs1872 for at least 6 -8 years now for AC and it was the best move I ever made. So quiet and much cheaper to run then the window units. Mine is an 18000 BTU. It also is a heat pump but only run it for a few hours for heat. It does work fine for heat , I just don't need it for heat. I installed it myself as they are fairly easy to install but did need to get an HVAC guy to vacuum the lines for me.

MtnDon
Member
# Posted: 28 Aug 2016 19:29
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Grid tie or off grid?

Both can be done, off grid requires a little more thought and a change in use pattern and a unit that can be programmed for partial power use. A friend in CA has been running a mini split for about 8 years now I think. Off grid entirely. Both heat and cool.

DaveBell
Moderator
# Posted: 28 Aug 2016 20:30
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Shady, is there a drain for the A/C?

Shadyacres
Member
# Posted: 28 Aug 2016 21:03 - Edited by: Shadyacres
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Yes , it drains on the outside. Mine , I had to drill a 3 inch diameter hole thru the wall and all the lines went thru there including the drain. The power is to be hooked up outside with a separate electrical cut off box. This is not at my cabin but may put one there some day. I don't really need the AC there much though.

FishPCreek
Member
# Posted: 28 Aug 2016 21:20
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Thanks for the quick replies. Mtndon, I am on grid, and figure the short amount of time I will actually need it for heat (woodstove=3 to 4 hours to get comfy) I will eat the extra electricity bill for it, given we get up there every 3 to 4 weeks. I like the point that the main compressor and drain part are outside. I have no idea how loud the outdoor unit is. I live in NoVA and our heat pump here is loud, but it is for a house, not a small cabin.

jarviscorona
Member
# Posted: 6 Jan 2017 06:48 - Edited by: jarviscorona
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I have been using ductless mini split air conditioner in my commercial space for almost 5 years. These air conditioners are small in size and flexible for heating and cooling rooms. Also these systems are often easier to install than other air conditioners. Like many other air conditioner these systems need to be maintained regularly for enhancing the efficiency. Have a peek here for more details about air conditioner services.

Julie2Oregon
Member
# Posted: 7 Jan 2017 03:48
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I'm very interested in a ductless mini-split to heat and cool my main cabin. (On-grid) I've read that they may be meh for heating in cold climates but they're coming out with models that have improved in that respect. For a small place (about 500 sq. ft.) and one with a pellet stove, would a regular mini-split still make sense in a place like Oregon?

Thoughts and considerations, please!

Notes
Member
# Posted: 7 Jan 2017 09:40
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I install and service ductless mini splits. We use them for cooling server rooms. 2 types, hermetic compressor heat pump will heat down to 20 degrees and inverter driven down to -10 degrees. Both need optional low ambient kits. Low ambient kits consist of controls to modulate condenser fan motor, crankcase heater, low and high pressure switches, and a wind baffle to stop wind from blowing through condeser.

creeky
Member
# Posted: 7 Jan 2017 12:56
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ashp are a no brainer now. the efficiency for small ones in particular is off the charts.

@Notes: how did your hot water boiler work out?

any tips on using say a air to water heat pump? My girlfriend wants to reduce her natural gas use. She uses a boiler for hot water and in floor hydronic.

I've designed a 6 solar panel/240 ac/lithium battery system to power what will probably be 2 systems. 1 air to water. And one air to air. The air to air is easy to figure out. The air to water is giving me a headache.

Notes
Member
# Posted: 7 Jan 2017 16:43
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Hi Creeky, the combi build is finished and worked well for our domestic water usage and heat when at the cabin. One major problem was the condensate freezing up. We are not at cabin enough to stop the freeze ups. Ended up with a split heat exchanger. I always drained and blew out drains, but the sealed combustion in and out pvc on warm days would cause condensation and freeze. I removed and am back with conventional water heater and heat exchanger for some minimal base board.
Your build sounds interesting is your heat pump water source? If so use the outlet water, should be about 110 degrees into a heat exchanger.

Notes
Member
# Posted: 7 Jan 2017 16:47
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Creeky, if heat pump is air to air and you want to heat water, the swimming pool community has a heat exchanger piped into discharge of compressor to heat pools.

creeky
Member
# Posted: 8 Jan 2017 21:15
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thx Notes.
Ya. The inverter heat pump is air to air for the out building (Gree Crown). Easy install. All the features I need.

For the main building I'm not sure what system to go with yet.

I will look into the swimming pool exchanger. Air to air is so much cheaper and easier to install.

At my farm I might go ground water. I have lots of it!

Asher
Member
# Posted: 9 Jan 2017 13:59
Reply 


I was on the fence between a mini-split and a PTAC system. I went with a PTAC unit for a couple reasons...

1- if there is a problem with the unit I can pull it and take it to town and have it serviced. (no need to be at the mercy of a HVAC tech out in the sticks).

2- the install requires no one else involved other then me...

3- I was told (verify this yourself) that mini-splits have special fittings for service.

My PTAC is a heat-pump unit with a back up electric heating element.

One of the biggest selling points on my PTAC was that it has a freeze feature built in... Even if the unit is turned off, it will turn on at 40 degrees and heat until it reaches 45 degrees and turn back off. When I leave, I just turn the unit off and walk out, no need to worry about winterizing the pipes like before...

Saturday night when I arrived at the cabin, the outside temp was 17 degrees, the (85% insulated) cabin was anywhere from 35-43 degrees inside. I walked into the cabin turned on the unit and within in 45 minutes the temp was 68 degrees.. My cabin is open ceiling, 17x40 ,with a 18' deep loft on one end.

My original plan is to install another smaller PTAC in the other end of the cabin once the interior walls are installed, and I thought just one wouldn't keep up, but so far I was wrong this one unit would easily heat and cool this cabin... I am still going to install another one, to help balance the air flow. Still 2 of these units are still much lower in price then 1 mini-split unit.

I was very surprised with the low noise level on this unit, much quieter then what I have ever experienced in typical hotel models... It is quiet enough that the wife needs another fan on at night for white noise.

Here is the unit I decided to go with...

https://www.alpinehomeair.com/viewproduct.cfm?productID=453070918

wgiles
Member
# Posted: 9 Jan 2017 15:03
Reply 


Since R-22 is supposed to be phased out, pretty much all new units that have service connections will come with something that you can't connect an old R-22 gauge set to. There should be adapters for most everything, but you have to know what kind of connection that you have. PTACs (or PTHPs) do not normally have service connections. This is normal since service connections are often slow leaks. I have a PTHP in my workshop and it's OK, but a mini Split would probably be more efficient. The biggest drawback to PTACs is that they require a 16" X 48" hole in the wall that only has a thin insulating layer between the conditioned space and the outside. Whenever the outdoor ambient temperature drops below 20 Deg. F, my PTHP switches from heat pump to resistance heat mode. If I come in to my workshop and turn the PTHP on to heat and the room temperature is more than a couple of degrees colder than the set temperature, the PTHP will switch to resistance heat mode until the temperature is close enough to the set temperature. I have a direct vented Propane wall furnace to maintain the heat when the outdoor temperature is low. Both are set to 58 Deg. F. Neither heater wants to be set to a lower temperature. The PTHP won't go lower than 58 Deg., the Propane heater thermostat is too finicky when set below 58. The PTHP will kick on if the temperature drops below 40 Deg, but only on resistance heat. My heated workshop room is 12' X 30' and the PTHP is 12000 BTU. It's enough, but I don't ask too much from it.

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