Mini-split heat pumps comments and questions

[Chuckanut]

My mini-split heat pump is going through its first sub freezing weather for a few days at least. Temperatures are mostly in the teens and 20’s during this time.

When I tested the heating feature of the mini-split earlier this year, it was pumping out 126 degree air with an outside ambient temperature of approximately 50 degrees. Today, with the outside temperature at 24 degrees it is pumping out 112 degree air. FWIW, Mitsubishi claims the unit operates effectively down to 17 degrees.

So, 14 degrees cooler. Based on sound the compressor is defiantly working harder though it’s still admirably quiet.

For those of you who measure such things to satisfy your curiosity, how does that compare?

 

[mpeirce]

It's really no surprise that difference mini-split units are perform differently.

We put in a Mitsubishi unit that promised performance down to 0°F and it has worked beautifully in such conditions. We've had nice heat from it well into the minus single digits (as low as we've experiences here so far).

Cheaper units won't perform as well, but hey, cost less to buy.

 

[Chuckanut]

It's really no surprise that difference mini-split units are perform differently.

We put in a Mitsubishi unit that promised performance down to 0°F and it has worked beautifully in such conditions. We've had nice heat from it well into the minus single digits (as low as we've experiences here so far).

Cheaper units won't perform as well, but hey, cost less to buy.

FWIW, I was not complaining about my unit. It has cut my December KW usage by 700 KW over the previous three year average. and even in 20 degree weather is pumping out a nice amount of heat. I could have bought a bigger unit, but not only would it cost more to purchase, but it also uses more power even on days when the extra capacity is not needed (which is most of the time).

I don't live in a very cold climate, mostly 30's to 40's in the two coldest months. I barely used my unit this summer as most days were in the 70's - time to open the windows and let in the fresh air. But occasionally, those rascally Canadians send an Arctic chill across the boarder to remind us that Canada hasn't gone anywhere.

 

[skyking1]

We have a pair of Pioneer 1 ton units that keep up until it gets into the 20's. It is not so much a function of the heat they put out, but more a function of how much more heat the house needs in those low temperatures.
It is 20 F outside and I turned the electric central heat on a few hours ago. It will stay on until Tuesday or so.

 

[old medic]

I'm looking forward to getting ours installed and seeing how they work.

 

[DrRoy]

Doesn't seem unusual that it works harder when it is colder.

 

[pjigar]

I haven't measured anything but I know our mini-split HVAC can't maintain the set temp when outside starts getting below 25-30 F range. e.g. last cold front, set temperature was 73 F, outside temp was about 15 F and inside temp was about 60 F. We just fire up our wood burning fireplace once temperature gets into teens which is only a few times in a year.

 

[Chuckanut]

I haven't measured anything but I know our mini-split HVAC can't maintain the set temp when outside starts getting below 25-30 F range. e.g. last cold front, set temperature was 73 F, outside temp was about 15 F and inside temp was about 60 F. We just fire up our wood burning fireplace once temperature gets into teens which is only a few times in a year.

I am finding that I need a boost from my base board heaters when the temps slip into the 20’s. But, that doesn’t happen often.

FWIW, my baseboard heaters were never enough when the temperature hit freezing or below. The house was always on the too cool side. Between the two source of heat, the house is now decently warm.

My desired winter temp is 68 to 70 max. Near freezing and below, baseboards kept the house near 64 and ran 90% of the time night and day to do that. Now the baseboards cycle on and off every 20 to 30 minutes. The mini-split operates all the time as it is designed to do unless I turn it off.

Yes, I have good insulation, and have plugged all the leaks I can, etc.

 

[Fermion]

It is -21 outside our house right now. What happens at those temps? Is it all just resistive heat then or do they still work somewhat?

I want what the turkeys and deer have. There are three deer outside and about 22 turkeys...I kind of thought they would be butterballs in this temp (a record low for this area)

 

[skyking1]

-21 is out of the realm of heat pumping, which is why I am installing a Ground Source Heat Pump (GSHP).
As the heating season wears on, the ground will cold soak down to about freezing at the lowest.

 

[euro]

It is -21 outside our house right now. What happens at those temps? Is it all just resistive heat then or do they still work somewhat?

I want what the turkeys and deer have. There are three deer outside and about 22 turkeys...I kind of thought they would be butterballs in this temp (a record low for this area)

Wow, you are at -21 in Seattle? Call me amazed as I lived there for 7 years and temps never even dropped into the + teens....
Or are we talking a cabin up on Stevens Pass or something? Just curious

 

[jimbee]

It is -21 outside our house right now. What happens at those temps? Is it all just resistive heat then or do they still work somewhat?

Is that -21F air temperature or wind chill? The wind chill temperature does not relate to the amount of energy in the air.

 

[skyking1]

He is now northwest of Spokane, where it is famous for severe polar air mass outbreaks.

 

[Fermion]

Yes, we are in NE Washington a bit north of Spokane. It gets colder here although not usually this cold. I do see that in Blaine where our sailboat is that the temps are pretty chilly as well.

The snow is great though. We rode Thursday at about 4500 feet elevation and it was 3 feet deep. I got a bit stuck when I went off trail but used the other sled to pull out.

 

[tulak]

I'm finding that the mini-split on the main floor is unable to keep up. I don't blame the mini-split, even though maybe I should have went with a higher BTU unit for this room. The gas fireplace isn't working and I'm realizing that there is a lots of cold air coming in from that area. Plus, insulation overall is probably lacking.

This wouldn't be an issue if the gas fireplace was working. It's giving me some thoughts on future improvements, but since this is a temporary home, I'm always hesitant to invest too much.