Using a mini split for heat in the winter?

[Calvin98]

Using a mini split for heat in the winter?

The mini split AC is great for cooling in the summer. Uses very little power, it’s quiet and very effective. We’ve been running off grid for about 2 1/2 months now and we’re also using the mini split for heat in the winter. Does a really good job with heating also. Wondering if anyone else uses them for heat in the winter also and how reliable that is?

Am I putting unnecessary wear and tear into on the machine by using it for heating in the winter also? Or is maybe a separate electrical heater to use for heating better? You can get little portable heaters for very low cost but the mini split is like to replace $1000 if it breaks

Are there any other electrical heaters that are safe to use and won’t fall over and cause fires? Only looking for something that would heat a relatively small room, the same as what the 12,000 BTU mini split can do. In heat mode with maximum fan, the mini split uses 1300 W.

Our mini splits, good long-term for heat and cooling? In other words, use them year-round for many years trouble free?

 

[Solar_Mann]

been using mine for heating and cooling for 2 years.

 

[timselectric]

I am using mini splits for both heating and cooling.
They do use more power for heating. But still more efficient than other options.

 

[Will Prowse]

Heating multiple buildings right now with 9 mini splits. Works great. Just need enough solar during winter to power them.

 

[HighDesertOffgrid]

I've used my 12k as heat for 4 winters. The SEER is derated by about 40% in heat mode. Being a heat pump the reversing valve just makes it draw heat from the outside air. Auto defrost runs occasionally as well.
Use will obviously wear moving parts which will decrease the lifespan proportionally.

 

[Madcodger]

Have three Mitsubishi Hyperheat (6K, 12K, 18K), in Maine. Love 'em and use just the 12K for heat in the super efficient apartment over the barn/garage (haven't even needed the 6K in the bedroom yet, for heating) with no issues at all. We wanted to see how the 18K did for heating the garage, but it's just too much of a drain on our batteries during winter. It could do it, and if we were on grid we'd use it all winter, but we've had to go with the propane-fueled hydronic for that large, high space to avoid draining down the batteries too much.

We had Daikin units in the previous property, just a few miles away but on grid. They worked very well for the four winters we had them before we sold the place, and they weren't as rugged as these Mitsubishi units, so don't worry about putting a strain on your heat pumps for heating. They're much more efficient than almost any other method.

 

[Farm Boy]

I have an 18k BTU I use on sunny days. My batteries seem to be fully charged at end of day and usually shut it off before going to bed when using as heat set at 80 degrees. Not much sun past 3 weeks here so it's been off. With out consistent sun this solar stuff lacks energy.

 

[MarkSolar]

I use mine for heat, but natural gas is cheap here (Chicago area), so below about 40F with higher humidities it's cheaper to turn it off and just use the house gas furnace. Even at low humidities it doesn't make economic sense around here to run it colder than about 25F. You can usually hear the reversing valve when the minisplit goes into defrost cycle, that's the point where the efficiency starts to drop. If your alternative heat is electric, you're probably better off using the minisplit even at the coldest temps because I don't think they ever drop as low as a COP of 1. But that of course depends if you have cheap electricity rates.

 

[Q-Dog]

I would like to try a minisplit for the back portion of our house (to cover our bedroom/bathroom area) but have limited wall space for mounting. Do any of you mini split users have a unit installed in a bedroom, near or over a bed? How does that work? Is the fan annoying or not an issue? What would you do differently.

 

[HighDesertOffgrid]

Do any of you mini split users have a unit installed in a bedroom, near or over a bed?

I have three installed in bedrooms and one over a bed.

Is the fan annoying or not an issue?

10x quieter than a window unit.

What would you do differently.

An approximately 3" hole has to be drilled through the wall for the refrigerant lines, power cord, and condensate line.
The condensate pan is shallow and can spit water if it is full. Angle the unit slightly in favor the condensate drain port and drill the exterior wall hole an inch below the interior hole for adequate drain.
Walk in the park.

 

[Zwy]

I use mine in winter for excess PV. If it gets too cold and affects efficiency, I switch to electric radiators.

 

[JaVid]

I use mine in winter for excess PV. If it gets too cold and affects efficiency, I switch to electric radiators.

I thought the mini splits more efficient than resistance heaters down to their rated minimum temp?

 

[JaVid]

Using a mini split for heat in the winter?

The mini split AC is great for cooling in the summer. Uses very little power, it’s quiet and very effective. We’ve been running off grid for about 2 1/2 months now and we’re also using the mini split for heat in the winter. Does a really good job with heating also. Wondering if anyone else uses them for heat in the winter also and how reliable that is?

Am I putting unnecessary wear and tear into on the machine by using it for heating in the winter also? Or is maybe a separate electrical heater to use for heating better? You can get little portable heaters for very low cost but the mini split is like to replace $1000 if it breaks

Are there any other electrical heaters that are safe to use and won’t fall over and cause fires? Only looking for something that would heat a relatively small room, the same as what the 12,000 BTU mini split can do. In heat mode with maximum fan, the mini split uses 1300 W.

Our mini splits, good long-term for heat and cooling? In other words, use them year-round for many years trouble free?

I installed (4) mini splits and run them on off-grid solar. They work great for heating, but off-grid, you cannot count on heating if you live in a place with real winter. I run mine as much as I can, but this time of year, I cannot count on running them 24/7 and need to do some sort of load management almost daily. Its a pain in the ass.

 

[Zwy]

I thought the mini splits more efficient than resistance heaters down to their rated minimum temp?

They are, but COP drops off below 20°F and eventually will go negative. It it due to low heat energy in ambient air plus the need to defrost.

It gets cold here in winter, -20°F is common in January. Usually below 10°F I will switch off the heat pumps. Defrost needs to take heat from the room to enable defrost of the outside unit.

If you know the AHRI number of the unit, go here and this will show performance charts for the unit in your area.

 

[740GLE]

I enjoy all these comment yet no one is really commenting what their average winter temperature is or how well insulated their place is?

Just like with all HVAC systems someone in say Virginia will have dramatically different experience than Fargo or say someone in Vegas winter isn’t quite the same as Maine.

Heck even in southern Maine by the Seacoast is dramatically different than the County.

I usually shut off our mini splits and burn wood when it’s consistently low in the 20s, (36k mistu hyper heat) right around mid November, which is usually our highest bills. I consider it a back up heating source for the rest of the winter. Our house is over 20 years old, it is 2x6 construction but is far from the most efficient, dirt cheap contractor grade windows that are a bit breezy.

As for the OP if you’re PV and batteries can support running the mini split, send it. It should be more efficient than say resistive base board heating.

 

[JaVid]

They are, but COP drops off below 20°F and eventually will go negative. It it due to low heat energy in ambient air plus the need to defrost.

It gets cold here in winter, -20°F is common in January. Usually below 10°F I will switch off the heat pumps. Defrost needs to take heat from the room to enable defrost of the outside unit.

If you know the AHRI number of the unit, go here and this will show performance charts for the unit in your area.

That's good info - thanks!

 

[Calvin98]

I would like to try a minisplit for the back portion of our house (to cover our bedroom/bathroom area) but have limited wall space for mounting. Do any of you mini split users have a unit installed in a bedroom, near or over a bed? How does that work? Is the fan annoying or not an issue? What would you do differently.

Yes. We do. Works fantastically well. The fan is super quiet and not a bother at all. Even on high speed it’s very quiet. We installed one early this summer and used it instead of the whole house AC to keep the bedroom cool at night. Major energy savings. 11 kWh versus up to about 70 kWh.

Wouldn’t do anything differently. Just wish I had done it sooner. The gree that we have you can control with Home Assistant so you can control it via the phone, which is nice.

Gree ac
Cooling mode:
Low 580w 7 kWh per 12 hours run
Med 750W. 3.1a 9kWh per 12 hr, 720w,
High 1130w 4.7a 13.56kwh /12hr run

Whole House 5ton ac 900w fan + 4500 w ac=5400w

12hr run = 66kwh

97 A start up. With the micro air easy start 30 A start up.

Mini split 12,000 btu
In heat mode:
Fan high. 1100 W.

 

[Calvin98]

10x quieter than a window unit.

Agreed. Window units are a pain. Kind of like sitting next to an EV on one side (super quiet) and on the other side, standing next to a muscle car with a big block Chevy and no mufflers.

Plus the window units suck in warm air from the outside. The mini split just has the cool air that circulates from around the inside of the house. If I remember right, the air coming out of the mini split was like 46°F. Nice and cool.

 

[Calvin98]

The condensate pan is shallow and can spit water if it is full.

Right. I had the indoor head unit slightly off of level and it was dripping water on the inside left side. Adjusted the angle of the head unit and everything flowed out the drain line like it was supposed to. No more problems.

 

[Calvin98]

They work great for heating, but off-grid, you cannot count on heating if you live in a place with real winter.

We are in Northern California at lower elevation so it doesn’t get too bad. Maybe two or three days of freezing and then above freezing temperatures the rest of the Winter.

 

[Calvin98]

As for the OP if you’re PV and batteries can support running the mini split, send it. It should be more efficient than say resistive base board heating.

After seeing all the comments, yes, I will. Not gonna bother with a little heater mounted on the floor that can fall over and catch fire. Going to use the mini split and going to use it hard. For heating that is. In the summertime, we already use it for cooling. This year we used to of the whole house. It did a really good job. Add a fraction of the power usage.

 

[Calvin98]

The whole house AC is a 35-year-old train unit that’s still running well. But as mentioned, it uses 67 kWh in a 12 hour. That’s kind of a lot to run off of at night. You need a huge battery to support that.

One odd thing that I found out that’s not related to any of this is that that old air conditioner has a built-in sump heater that is on 24 seven 365. Never knew that. Left the AC on all year long and probably wasted hundreds or even thousands of kilowatt hours over the last 20 years. Maybe newer units turn the heaters off, but this one is so old it’s on all the time.

So much good information here. Appreciate all the replies. Definitely going to stick with the mini split for heat in the winter in addition to cooling in the summer. Might even buy more.

 

[Calvin98]

By the way, I specifically chose a 240 V unit because it would pull lower amps and could use smaller wire gauge. We’ve been running off grid for 2 1/2 months now and it’s working fine. No problems at all. We had one hiccup a few days ago. I turned it on in the morning all of a sudden the head unit stopped turning the fan. I checked the outside unit and the were cold. My guess from the comments above are that it was probably in a defrost cycle. Normally the valves are warm when it’s in a heating mode. That has not happened again and always run in heating mode since then. No problem.

Technically, the specifications were 230 V but in the data sheet it shows that the unit can go up to 253 V so I figured we’d be OK.

I figured that the 240 V unit would put an equal load on L1 and L2 and the inverters would be happier than having an unbalanced load running even if it was so small.

 

[rhino]

https://www.energy.gov/eere/buildings/residential-cold-climate-heat-pump-challenge

One of the challenge segments was to have a cold climate heat pump optimized for -15F air temp. Supposedly these companies listed are going to put these in production now.

 

[timselectric]

I figured that the 240 V unit would put an equal load on L1 and L2 and the inverters would be happier than having an unbalanced load running even if it was so small.

This is exactly why everything I buy new or replace existing, I choose the 240v version.