Doing great! New Mitsubishis here. Ran the pipes overnight, kept the baby warm and cozy with a nursery heater. But also, I'm in SoVT like most of this sub isn't, so we're not as cold as y'all up there.

I don't really use my heat pumps in the winter for anything but air circulation in my new house. Just my woodstove from Nov to April.

But in the past I've had no issue running my Mitsubishi or others (Fujitsu and LG) down to -10F or -15F, they just heat cycle a lot and use a lot of power, without creating a ton of heat...but no issues beyond that.

Doing great. Comfy warm. Same as any other day. We got Bosch with aux heat coil installed 11/22. Heat pump functions to -4 then the coil provides heat below that. We chose it for the high praise for how well it does at low temps due to the aux heat coil. $20k included install and electric upgrade at pole. Loan pmt = $300/mo. Dec elec bill = $300. Thermostat set to 70.

1400sf leaky not zoned 1868 home with some insulation but not amazing insulation, huge leaky windows (former one-room school house). Windows currently frosted up all the way to the top which we rarely see. Bedrooms have no doors. Upstairs and downstairs open air flow. Near Stowe. None of our pipes go up external walls.

Very pleased so far. Will know more after next 2 month’s elec bill.

We happen to be Ideally located/positioned for solar if need be.

Our oil furnace broke/disintegrated. We have no back-up other than a space heater (which we haven’t felt any need to use). Space heater has auto temp setting and will shut off if it falls down.

Public Service Announcement: just learned this year that space heaters need to be plugged into walls (not plugged into extension cords).

Update:

1. still cozy warm inside 70 degrees 8p. -18 outside.

2. Saturday. 7:30a still cozy 72 inside. -19 outside.

Heat pump work regardless of the outside temp. When the temp gets below the rating, it doesn’t stop working, it just becomes more expensive than other electric heaters to operate. Would you need a backup heat source? No more than you’d need a backup water heater. Would it be cheaper to have a wood stove with heat pumps as a secondary system? It has been so far for us.

Daikin, installed in 2018. It's rated down to 5F, but I switch to propane at 15F. Ran them most of the time this winter, until this weekend. Worst electric bill was $150 higher than not running them. Keeps the house at 68F-70F no problem.

You should do a post in a couple months following up; I've also got an 1830s home that's heated with water pipes in baseboards and the oil fired water furnace is just tearing through our supply of oil. Really need to change it at some point

This is not accurate. Most units auto shutdown at some temp below zero to avoid damaging the compressor. The few units that will not do this generally have resistive backup to help keep the low side pressures within an acceptable range.

The shutdown temps range from -5 to -30f depending on make, model and refrigerant. Most are in the -15 to -25 range. Fortunately we’re not at those temps until tomorrow morning for a few hours.

We have two daikin 15k high walls and they have worked great. We also have a 24k Samsung that has been working great. Samsungs suck in reliability and service/parts so I’d steer away, but it was free leftover for a job so it went in our shop.

That said, when it’s below 20 or so we run our wood stove. Based on the submittal sheet they should heat our place sufficiently down to about -10f, they just won’t be efficient while doing it.

I'm cheating, I still have the oil-fired furnace as backup. I do need to work with the installer to tune the heat pump settings; I'd like it to go lower than it currently does because I have a lot of excess solar generation credits I want to use up.

Doing great, I have the pellet stove going as well, but the air coming out of the Mitsubishi heat pumps is as warm as I like

Piggybacking off this. At lower Temps units struggle to pull heat from the air and thus become less efficient and less effective. There are Temps so cold that your heat pump cannot provide necessary heat to the room.

I believe the rule is they become less cost efficient at 20 or below.

I have a Mitsubishi two zone for our main house and then a Fujitsu smaller unit for my office, both are doing just fine. The Fujitsu is a bit noisy. Both structures are insulated with spray foam and spent a fair amount of time air sealing. We also installed a ERV for fresh air. Overall things are warm.

We have a small portrait fireplace in the living room that makes it comfortable in the evenings.

We don’t change the thermostat up or down. We keep it at a constant 68F.

The only thing with the setup is that during Uber cold temps, it’s helpful to keep the bedroom doors cracked at night to allow heat in. It’s not a biggie to us.

Have Carrier Infinities (2) They seem to keep up all the way down to -15 and beyond. But we're also cheating a bit by throwing in a woodstove

I was going to make a separate post about this later (still gathering data), but currently it is -9f outside my house, and the house is right at 70 degrees with heat pumps only. No supplemental heat aside from baking some cookies a few hours ago. The real test will be tonight when we get to -13, but so far so good.

Happy to read this. We have a Daikin model good down to 5°f as well. Thought about going for the -15°f model but really couldn’t justify it. Run the wood stove almost around the clock late fall to early spring. Got it mostly for the shoulder season and the summers.

Yes, agreed! Would like to make the switch too. I’ve got an 1840s house with baseboard heat and an oil-thirsty old boiler.

So far so good. Zero degrees in Dorset, and my three Haier units are keeping the house at 70 with no issue. Installed this past summer. I turned on the oil burner this morning and set its thermostat at 64 as a fallback, but the circulators have not needed to come on at all. House is about 2600sf, but about a third of that is a basement room which I'm not heating. It's dropped to 51 down there today. 3 sides of the basement are below grade, so it's fairly stable down there.

Is your Mitsubishi a cold-climate model? It should create plenty of heat down to -15 if sized appropriately for the heating load.

“At single-digit temperatures, the efficiency of heat pumps drops by almost half compared to 47°F temperature (HSPF rating, for example, is measured at 47°F).”

47°F is equivalent to 8°C, which is 281K.

^(I'm a bot that converts temperature between two units humans can understand, then convert it to Kelvin for bots and physicists to understand)

This will vary dramatically on the model. Most run at 100% efficiency down to around 20f. Cold-climate models will maintain their cost efficiency compared to oil, LNG, or LP to below 0f and operate below -20f when needed.

Yes, it’s an older H2i model and is at my folks camp, which is poorly insulated and was somewhat undersized. I think that generation H2i had a hard shut-off at -13F or -15F. My current house is super well insulated and the Fujitsu compressor is appropriately sized for the four inside heads, and the heat/cool load of the house. I have no doubt it would keep my place comfy in this weather, just at a high electric usage rate. I burn wood as it’s cheaper and my wood stove is modern.

I have propane backup. I don’t know how tech is these days, but I personally wouldn’t count on a heat pump alone.

We turned ours off and have the oil on, it would be functioning in auxiliary and be $$$ to run at the moment.

My single heat pump heats 90% of my house (1500squ ft) I’ve used maybe 30gallons of oil the whole winter.

We should start a club. LOL.

Mine is working totally fine. Temp in the house is exactly what I have it set at. I have two Mitsubishi heat pumps. A 12k btu system downstairs in 1/2 finished basement and 18k btu system upstairs. Noticed the aux heat coil came on on the one downstairs but the one upstairs hasn't come on.

How much of your electric bill is due to the heat pump?

Not sure. We are all electric

I have a Fujitsu with an air handler for two adjacent rooms, that's ~8 years old. It's currently -6 out, the air coming out of the vent vaguely warm. We supplement with a wood fireplace insert.

Daikin 4 zone system has been keeping up just fine. -8 right now and 70 in the house. it's been through -20 before and it did fine. my electric bill will be higher this month, but nothing compared to oil or propane would cost

I understand where you're coming from, but the tech has come so far. you don't need propane or oil anymore. most new residential and multi family buildings are all heat pump with no backup

My wife keeps saying we should get a heat pump. I had no idea it was $20k installed. Seems like with the increased electricity cost and the purchase/install costs, it would take a long time to make your money back in not using oil or propane heat?

I just turned mine (Daikin ductless mini splits) on to test it out and they are working pretty well. -8 with a -29 real feel. I'm sure they won't make it too much longer as it is just going to get colder. Looking forward to getting a wood stove next year too.

We have a adorable little 11k btu Rinnai in the basement and a single Fujitsu 15RLS3H (if I remember right) on first floor. It heats fine. This is a well insulated 1800 sq ft house. We do have a wood stove I don’t NEED to use but it’s good to have.

I would say I wouldn’t want just the heat pump. I’d want at least a gas backup or wood stove.

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The real problem is the opportunity cost of spending 20k that isn’t going into mutual funds, retirement savings, extra house payments.

Heating mostly with natural gas and supplement with a wood stove mostly for ambiance out in Underhill. We keep the heat at ~70 and I haven't had a bill over $120 / month yet. 1800 sf home - reasonably well insulated with dual pane windows.

I think a heat pump is good for folks that live where you can't get VGS. But otherwise LNG is far more cost efficient in this state. If anything, the heat pumps best usage for me would be for air conditioning.

I installed 3 Gree Sapphire units a couple months ago. I decided to turn them off and turn on the furnace this afternoon when it was -12F. The power draw was almost double normal. Note, right now at -17 the furnace is not keeping up.

1200sf 2 story house, 18k centrally ducted Mistubishi. Most would consider this quite undersized! But we got our home sealed and insulated beforehand. We do well, but start to droop when it gets below -5 (currently mid sixties in the house and -13 outside). Last winter we had a -15 to 0 stretch for 48 hrs and the house stayed in the 60s.

Huge caveat here. We have an internal electric resistance duct heater that is NOT working and has never worked due to a broken relay we discovered today. It's 5 kW on a dedicated 30 Amp breaker. If this was working I'm sure we'd be up to 70F indoors no problem. Get your installer to test the backup electric heat!

Horrible

We are burning wood too

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Vermont Energy Contracting & Supply. I'm in Chittenden County. Love the ducted system, they just tore out the furnace and replaced it with an air handler with a heat pump coil and one outdoor unit. We repurposed existing ductwork so no noticeable difference outside the basement.

It won't take as long after the legislature gets done.Silver lining to the price of oil/propane going even further up next year.
We won't talk about the cost of electricity.
Of course you could put in solar for another 20k no problem.

will not do the trick in this state great for fall and cooling the house during the summer