Using ductless mini split for heating?

solarvic · February 6

Is anyone using ductiess mini split for heating? I am going to try it since propane is getting so expensive. Have been watching lots of Youtube and they say it is more economical to heat with a ductless minisplit than propane. I want to buy one with hyper heat and would like to hear about any recomendations or experience with them. I do not know why there are blue and red underlines on my post and I don,t want anyone to think I am rude.

Ralph Day · February 6

I have a Mitsubishi mini split. It's only 1 air handler, about 12500btu. It augments the woodstove for heating the whole house. At -25C it still puts out some heat, though less efficiently than at higher temperatures. I'd go with it if I were you, but not for whole house heating in my case.

Dave Angelini · February 6

Definitely doable offgrid if your power system is designed for it. In the coldest snow storm we still use a woodstove but much of our winter in the southern Sierra is pretty mild compared to 100 miles north. We heat with a 30+ SEER split that is 9,000 btu. Turn it off at sundown and on at 7am. We do have one for a spare but never use them both.

I know it would be cheaper than propane but you need to buy the best models not the lower SEER units. The zoned splits are not as high SEER as the individual ones like Ralph and we have. Hey Ralph 😎 -25C is a typo?

solarvic · February 6

I am grid tied. I have enough solar that covered my entire electric bill till the hybrid water heaters heat pump failed. Probably won,t replace it, just running on the heating elements. If I take the window air conditioning off grid I still might be able to cover most of my electric bill for the year. I started an off grid system for backup last summer but got the covid and could,nt finish it. Just now am starting to feel more normal and I am going to finish it after spring breaks. I have all the equipment I need to probably run the mini split off grid part of the time. I am searching for an automatic transfer switch that imonitors the battery state of charge and switches to the grid when needed. Amazon has one but it is for 120 volt. I need one for 230 volt. Anyone know where to get one?

mike95490 · February 6

solarvic said:

........ I am searching for an automatic transfer switch that imonitors the battery state of charge and switches to the grid when needed. Amazon has one but it is for 120 volt. I need one for 230 volt. Anyone know where to get one?

Use the 120V transfer switch as a control relay for a pair of 240VAC well pump contactors ? With the proper ratings.

solar_dave · February 6

I have a Dakin heat pump on my office/shop building, we use it to both heat and cool, 3ton unit with 3 heads. Easy here in Phoenix on the heat pump side as we rarely see sub freezing temps.

Ralph Day · February 7

No Dave, it works at -25C. Just not very efficiently. I only use it when our overnight temps get below -10C or when I don't want the excessive heat the wood stove can produce when it's not far off freezing. Wood is cheaper than electric. I burn about 4-5 cords each year, harvested from my own property. A new chainsaw every 15 years, a new woodstove every 15 years, gas, oil, chains and bars...maybe amortizes out to under $500 per year. Extra utility power costs, maybe $100 over 6 months of winter.

AC takes much less power, so in the summer when it's hot the heat pump can run off the renewables. The delta T for heating is just too great as reflected in the power usage. The pump is 240vac, runs off a Trace autotransformer (house has an Outback VFXR3648 single inverter, 120v available). Putting it on a Kill-a-watt meter shows about 500watts for AC, 950-2500watts for heating. Beyond the capabilities of the system unless it's really sunny and windy and in float.

The nice thing about having utility power is the comfort level the heat pump can give in winter and summer. Nice quiet, even temperatures achievable with not too much cost in power or dollars.

Dave Angelini · February 7

Very similar to here what you wrote, except no utility and 30F is as low outside as we have been in 20 years.
The LG 30 seer split is often using less than 300 watts. It can use 1,500 w when the differential is more than 3 degrees.

solarvic · February 7

dave angelia Is the sanyo still working? I bought one in 2010 and installed inside air handler and never installed the the outside unit. Now I am going to finish installing it this spring. It is at one end of my home in the master bedroom and will be powered by the grid. I plan on getting a new 12000 or 18000 btu mini with hyper heat for the other end on my kitchen wall and think it should heat kitchen and living room. I Have 3 or 4 brands I am considering Bosch, Cooper & Hunter,, Gree, LG. which wouldn,t have a warranty because I am self installing. MR COOL has some DYI models that give warranty if you do a DYI install but they do not have HYPER heat.

Marc Kurth · February 7

Dave Angelini said:

Very similar to here what you wrote, except no utility and 30F is as low outside as we have been in 20 years.
The LG 30 seer split is often using less than 300 watts. It can use 1,500 w when the differential is more than 3 degrees.

OK, that 30F surprises me!! I would have bet on 20-25F.

Dave Angelini · February 8

Yes the Sanyo still is working as a spare. Going to 240vac really helped the specs on power. Another mistake of not using the best models which are all 240vac, I believe.

It is all about local weather and terrain in the southern sierra. The other term for this is micro climates. We have deep canyons below us that can hit 25F. Up here on the ridge top it is often 15 degrees warmer. Our snow never stays more than a day and bright blue skies follow storms in hours.

I have not heard much good on how Texas did this winter. It really surprised me 2 years back. I would have never thought that of Texas and power in winter.

Marc Kurth · February 9

Dave, that makes sense. I now remember a friend who lived outside of Coarsegold, often talked about the temperature gradient/thermocline up and down his mountain.

We are good down here! Our part of North Texas just went through a hard freeze with 19F-23F nights and 26F-28F days. I just hunkered down for 2 days and stayed well lubricated. Snow and ice are melted and we are back up into the upper 60s and low 70s and sunny. We did get a little rain (4") out of the deal too.

solarvic · February 9

Use the 120V transfer switch as a control relay for a pair of 240VAC well pump contactors ? With the proper ratings. Mike are you suggesting the pressure switch or something else? I think I might not know for sure about what kind of contactors you might be referring tobut I like your idea.

mike95490 · February 9

> Use the 120V transfer switch as a control relay for a pair of 240VAC well pump contactors ?

Yes, They are likely to consume a bit more power, you may need a transformer, but you could wire them NC (normally closed) for solar, Contactors are likely to glitch/bounce as they switch, they aren't precision relays like what a UPS uses,

Using ductless mini split for heating?

Comments