Costco now selling DIY mini splits.

Seasoned Oak

Minister of Fire
Oct 17, 2008
7,071
Eastern Central PA
Spend some bucks sealing leaks and improving insulation on the house and you may only need 2 mini-splits. Improvements in the house envelope's insulation will payback year-round during the cooling and heating seasons.
This cant be emphasized enough. Every time i do a nice tight rehab i cant get over how little energy it takes to keep it warm and cool. But then you have those who will open the windows on 95 degree days when the house is 75 inside.
 

CaptSpiff

Feeling the Heat
Jan 13, 2014
481
Long Island, NY
Air sealing/insulating this place is sort of a never ending project (I buy Great Stuff by the case !!!) that I pick up and put down whenever I have time. I think maybe we could get by with 3 (4.5 tons) but 2 would probably be a undersized for our square footage and climate zone even with better insulation and air sealing.
Beware the "sales pitch" of bigger tonnage is better. I much prefer a Unit pulling out the humidity by running longer, compared to walking into a cold but clammy room.
 

Swamp_Yankee

New Member
Oct 18, 2018
59
Hunterdon County, NJ
Beware the "sales pitch" of bigger tonnage is better. I much prefer a Unit pulling out the humidity by running longer, compared to walking into a cold but clammy room.
True, but this is where mini-splits shine. With 3 or 4 units I can operate each one individually, so if/when I need 4.5-6 tons I can run the system full out, but when I don't, I can shut some of them off, and do it with voice commands to boot.
 

Swamp_Yankee

New Member
Oct 18, 2018
59
Hunterdon County, NJ
IMO buying splits that aren't max efficiency cold climate capable is kind of a waste of potential.
I already have heat-I need air conditioning, and this is the best way to do it. I'd love to build a superinsulated net-zero house with ground source heat pumps for all heating and cooling needs powered by off-grid solar, but for right now, I'm working with what I've got.
 

fbelec

Minister of Fire
Nov 23, 2005
2,705
Massachusetts
This cant be emphasized enough. Every time i do a nice tight rehab i cant get over how little energy it takes to keep it warm and cool. But then you have those who will open the windows on 95 degree days when the house is 75 inside.
boy do i understand this
 
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peakbagger

Minister of Fire
Jul 11, 2008
5,297
Northern NH
boy do i understand this
Just as bad are the folks who leave the windows open in damp weather with high relative humidity and then complain the AC will not cool the place down. They dont realize how much capacity is used up condensing water vapor out of the air. Far better to leave it running with windows closed despite the marginally cooler temps outdoors.
 

hockeypuck

Feeling the Heat
Sep 6, 2009
314
south central NH
I just installed a 2 ton diy mr cool. Did everything myself. Install was pretty easy. Works great. Obviously longevity is a concern, but since I do not live in Florida where AC is a must, I felt the savings was worth the risk. So glad the noisy window units are no longer needed. It is quiet inside and out. Outside side condenser is surprisingly quiet, so those who might be afraid of disturbing neighbors, I would not worry.

Now if I lived in an area where you needed AC to keep your house from molding up, I would spend the money and have a local reputable shop put in the AC of their recommendation.
 

semipro

Minister of Fire
Jan 12, 2009
3,810
SW Virginia
I just installed a 2 ton diy mr cool. Did everything myself. Install was pretty easy. Works great. Obviously longevity is a concern, but since I do not live in Florida where AC is a must, I felt the savings was worth the risk. So glad the noisy window units are no longer needed. It is quiet inside and out. Outside side condenser is surprisingly quiet, so those who might be afraid of disturbing neighbors, I would not worry.

Now if I lived in an area where you needed AC to keep your house from molding up, I would spend the money and have a local reputable shop put in the AC of their recommendation.
Thanks for sharing that. Outside noise is a major concern to me.
 
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hockeypuck

Feeling the Heat
Sep 6, 2009
314
south central NH
Why? I just did a 1.5 ton Mr. Cool on our second floor and its fantastic-and we definitely need it here (NJ).
I am not sure of the climate in your area but in Florida, if you loose ac for a while, mold will grow inside the house. I do not have to worry about that here in NH. My point was around the durability and serviceability of these units. Unknown at this point. Not sure how a local HVAC guy would deal with this unit, if at all. When I was installing generators, I would not touch a generac whole house unit (mid 2000's). One you service a unit, the owner thinks its your responsibility now. I bought this unit with eyes wide open. I have friends in the HVAC industry that could charge this if necessary, but I would not hold them accountable for any future issues.
 

Brian26

Feeling the Heat
Sep 20, 2013
493
Branford, CT
IMO buying splits that aren't max efficiency cold climate capable is kind of a waste of potential.
I looked into the Mr cool units but the heating capacity is pretty terrible. They start dropping off capacity at like 45-50 degrees. Good cold weather units can put out 100 percent capacity below zero. I would use these for cooling only.
Screenshot_20190714-053041_Drive.jpg
 
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Highbeam

Minister of Fire
Dec 28, 2006
17,230
Mt. Rainier Foothills, WA
I looked into the Mr cool units but the heating capacity is pretty terrible. They start dropping off capacity at like 45-50 degrees. Good cold weather units can put out 100 percent capacity below zero. I would use these for cooling only.
View attachment 245699
Looks like they drop to like 40% of rated capacity at zero degrees. Just buy 2.5 times the rated capacity you need or maybe a few of these units.

I’ve wondered if this isn’t just a shell game where the good brands just underrate their equipment so that they still deliver at low temps.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,297
Northern NH
Having lived through a couple of cold winters with my Mitsubishi cold climate I can confirm that yes it does put out heat down to -10 but not much. Folks forget that as the temp drops the heating demand goes up significantly so they are trying to heat a house with a unit that is derated.

A friend of the family is selling rebuilt Monitors kerosene heaters to people who thought they could heat their house in cold climate with cold source minisplit. Its great supplemental heat in standard home but plan on another sources of heat for really cold conditions like a wood stove and a pile of seasoned wood.
 

begreen

Mooderator
Staff member
Nov 18, 2005
82,668
South Puget Sound, WA
Yes, you'll want to have a backup supplement unless living in a milder climate than NH. This is a hyper-heat unit, right? How well does it heat the place at +10 or 15ºF?

A ducted system makes this option easier. Adding a resistance coil box is straight forward. I am considering this path now that Mitsubishi and Daikin are making replacement options for central hvac systems. Our system was high-end in 2006, but it cuts over to resistance heat at 25º. We are burning wood at that point, but during a bad temperature inversion and burn ban we are running on the electric heat coils.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,297
Northern NH
I only have a one ton hyper heat unit on my main floor. I can carry my house if its 20 F or higher. and running 24/7. Anything consistently less than 20 F and it reallly cant keep up as the heat loss from the house probably exceeds the units rating. Around 10 F especially on snowy days it starts to defrost more often and the air temp leaving the unit is cooling down. Its still warmer than the room temp. I have an oil furnace as my ultimate backup if I not around to feed the boiler. Sure I could install more units but hard to justify 3K for something that wouldnt need t be used often.

A utility in Maine was one the first to really push cold climate minisplits. They never represented them a the only heat source. Maine has old housing stock and seniors so the concept was keep the main house cool using the existing heating system and then warm up a day space with minisplit for the owners to hang out in during the day.
 

begreen

Mooderator
Staff member
Nov 18, 2005
82,668
South Puget Sound, WA
Ah, so it's also a case of insufficient capacity. I'm impressed that a single 1ton can heat the place down to 20º. How many sq ft in the house?
 

peakbagger

Minister of Fire
Jul 11, 2008
5,297
Northern NH
950 square foot first floor and about 350 square feet of heated space on the second floor. Built 1988, 2x6 walls and a few walls have been retrofit with 1/2" isoboard inside the studs and the majority of the windows have cellular blinds with side tracks.
 

begreen

Mooderator
Staff member
Nov 18, 2005
82,668
South Puget Sound, WA
That's a long way better than our old house. 3 ton heat pump is working hard at 25º.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,297
Northern NH
I guess we need to come up with new word that lines up with the "Negawatts" concept and call it "Negabtus". The cheapest BTU is one you dont need ;)
 
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Swamp_Yankee

New Member
Oct 18, 2018
59
Hunterdon County, NJ
I am not sure of the climate in your area but in Florida, if you loose ac for a while, mold will grow inside the house. I do not have to worry about that here in NH. My point was around the durability and serviceability of these units. Unknown at this point. Not sure how a local HVAC guy would deal with this unit, if at all. When I was installing generators, I would not touch a generac whole house unit (mid 2000's). One you service a unit, the owner thinks its your responsibility now. I bought this unit with eyes wide open. I have friends in the HVAC industry that could charge this if necessary, but I would not hold them accountable for any future issues.
I think Mr. Cool did their homework as far as their intended customer base with these units. If you're willing to buy one, run the dedicated 20A/240V circuit yourself, mount the units, drill a hole in the side of your house, etc...you're not just going to continuously call an HVAC pro for repairs and "hold their responsible," if and when something goes wrong. Rather, they are going to figure it out themselves or find someone who can help. I spoke with a buddy who is an HVAC pro who told me that if I ever had issues that he would look at it, and in all likelihood the parts were generic. These things are all made by two or three huge companies in China and a lot of the parts are the same.

I looked into the Mr cool units but the heating capacity is pretty terrible. They start dropping off capacity at like 45-50 degrees. Good cold weather units can put out 100 percent capacity below zero. I would use these for cooling only. View attachment 245699
I doubt I'll ever use mine for heating. For us these were a low-cost DIY solution to a 120 year old farmhouse with no AC and no ductwork and so far it's working great. After enduring last summer either being uncomfortably hot while trying to sleep at night and/or having to sleep with the drone of a window shaker in my ear, this summer is a dream come true. We set the unit to "Dry" at night before we go to bed. It runs just enough to cut the humidity down-last night we were sitting in our bedroom watching the evening news and though it was 78°F in the room we were perfectly comfortable because the humidity was so low.
 

begreen

Mooderator
Staff member
Nov 18, 2005
82,668
South Puget Sound, WA
It should be great for shoulder season heating. I'd try it out.
 

hockeypuck

Feeling the Heat
Sep 6, 2009
314
south central NH
I had Dakin unit in my other house and all I used for was cool september and october mornings. I have a pellet, wood and oil heat. Really could care less about the heating capability. Getting rid of the window AC units was a must.