Advancements in cold climate heat pump efficiency.

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Brian26

Minister of Fire
Sep 20, 2013
604
Branford, CT
I don't know much about them but this company sells an air to liquid unit. https://www.chiltrix.com/chiller-technology.html
Rather pricey as I remember, I think $4k just for the outdoor unit.

I think this is where the technology is heading. Here in New England most homes have baseboard hot water heat or radiators. The fact that the unit is self contained and you just need to run water lines would make installations quick and easy.


I
 
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Highbeam

Minister of Fire
Dec 28, 2006
19,050
Mt. Rainier Foothills, WA
If you can heat your whole house comfortably with a single woodstove in one room then I see no reason to think that a single indoor condenser wouldn’t heat the home at least as well from that same room.

I live in a heating only climate and see no reason for putting in any more of those ugly wall units than I must.
 

UpStateNY

Feeling the Heat
May 4, 2008
401
Catskill Mountains
This is a great thread for the Wood Pellet forum folks to read. To save on cost of heating, I pretty much stop using my 2008 Harman pellet stove. On that note are there any fuel comparisons web applicatons like this one that include the cost of BTU for these high efficient mini-split ductless compressors? If someone created that I think you would see a lot more people stop using the wood pellet stoves at $6.00 a bag of quality pellets.

 
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peakbagger

Minister of Fire
Jul 11, 2008
6,399
Northern NH
It not a simple chart, The heating efficiency of a minisplit varies with outdoor temperature. As the temps drop, the minisplit eventually turns into a electric heater.
 

Brian26

Minister of Fire
Sep 20, 2013
604
Branford, CT
It not a simple chart, The heating efficiency of a minisplit varies with outdoor temperature. As the temps drop, the minisplit eventually turns into a electric heater.


Its actually pretty easy to get a rough comparison using the NEEP cold climate heat pump site I linked earlier. That has the COP numbers at various temperatures at max speed.

You can convert the COP to electric efficiency in that fuel cost calculator easily. Just remove the decimal point and enter the percentage value in the calculator for electric heat efficiency. Example a COP of 2.88 is 288% efficiency for electric heat.

Using the LG I linked in the first post that has a COP of 2.88 at 5 degrees and COP of 4.55 at 47. Here is what it would cost per million btu compared to pellets. I left the .12 kwh in the calculator that is probably the national average and left the default $245 a ton for pellets.

Pellet cost per million ton at $245 ton.
$19.15

Mini split at 47 degrees with a COP of 4.55
$7.73

At 5 degrees with a COP of 2.88.
$12.21

An important thing with the listed COP's number is that is when the unit is running at max compressor speed. When inverters are running at partial load the efficiency significantly increases. I have seen some Mitsubishi numbers where COP's are in the double digits like 11 or 12 at low speed st 47 degrees. At those efficiencies your looking at like $4 per million btu.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,399
Northern NH
So to satisfy the posters request, make up a simple chart that covers a range of COPs, compressor speeds for a range of manufacturers models that compares a range of pellet stoves efficiencies at various fuel and electric prices with local climate conditions factored in. IMO, an Excel model with a lot of look up tables is going to be needed.
 

Brian26

Minister of Fire
Sep 20, 2013
604
Branford, CT
So to satisfy the posters request, make up a simple chart that covers a range of COPs, compressor speeds for a range of manufacturers models that compares a range of pellet stoves efficiencies at various fuel and electric prices with local climate conditions factored in. IMO, an Excel model with a lot of look up tables is going to be needed.

No need to do all that work. An easier method is to use the HSPF rating (Heating Season Performance Factor). HSPF is defined as the ratio of heat output over the heating season to electricity used. The HSPF number is divided by 3412 to get a seasonal COP. 3412 is the amount of btus per kw of electric resistance heat.

Let's take the popular Mitsubishi MSZ-FH12NA with a HSPF of 12.5/3412 is a seasonal COP of 3.6

Cost for a million BTUs would be $10.55

Here is my Gree Sapphire 12k with a HSPF of 15. Seasonal COP of 4.4

$7.99 per million btu .

Even a mini split running at a COP of 2 is cheaper than wood pellets at $19.15 per million btu.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,399
Northern NH
I still dont see a chart
 

Highbeam

Minister of Fire
Dec 28, 2006
19,050
Mt. Rainier Foothills, WA
I don’t need a chart to get the very valid point that even at 5 degrees, the mini split is beating the snot out of pellets at cost per btu.

I just wish they didn’t look so silly!
 

UpStateNY

Feeling the Heat
May 4, 2008
401
Catskill Mountains

begreen

Mooderator
Staff member
Nov 18, 2005
88,839
South Puget Sound, WA

UpStateNY

Feeling the Heat
May 4, 2008
401
Catskill Mountains
What system did you have installed? Does it have resistance coil heat for backup? If yes, what is the crossover temp to the resistance heat coils?
Fujitsu - AOU24RLXFZH
Advertised Compressor to work down to -15F with ZH model.

Not sure if it has a resistance coil. You can google the model number if interested.
 

begreen

Mooderator
Staff member
Nov 18, 2005
88,839
South Puget Sound, WA
Thanks. That's a new system for me. I will look into it. I like Fujitsu, they have been making good, super-efficient equipment for a long time. And I see they make a 3 ton unit too.
 

begreen

Mooderator
Staff member
Nov 18, 2005
88,839
South Puget Sound, WA
Fujitsu - AOU24RLXFZH
Advertised Compressor to work down to -15F with ZH model.
This appears to be for a non-ducted system. Their Fujitsu - FO3620RVJCAB is for ducted. It's not ultra low, but would have enough heat ouput at 20º to cover our house.
 

Woodspliter

Member
Jan 25, 2020
131
Maine
I ve been thinking about putting in a few singles in my 1100 Sq range one in the finished basement one in one living room kitchen area and a small 6k in the master bedroom. I've looked into the top three in my opinion mitsubishi fujitsu and daikin. I'm leaning towards the mitsubishi for the sizing and btu output. People are pretty put off by the look of the indoor units but I don't mind them I'd rather look a one box on the wall than put a bunch on holes in my floor to install base board
 

begreen

Mooderator
Staff member
Nov 18, 2005
88,839
South Puget Sound, WA
I ve been thinking about putting in a few singles in my 1100 Sq range one in the finished basement one in one living room kitchen area and a small 6k in the master bedroom. I've looked into the top three in my opinion mitsubishi fujitsu and daikin. I'm leaning towards the mitsubishi for the sizing and btu output. People are pretty put off by the look of the indoor units but I don't mind them I'd rather look a one box on the wall than put a bunch on holes in my floor to install base board
So far it seems mainly Highbeam that strongly objects to the look of the wall units. They don't bother me. We have seen them so much in our travels around Asia that I take them for granted now. I have recommended and been in several houses with them, old and new. Quite frankly after a while you just ignore them. However, these companies also make radiator style wall units and ceiling units as options.
 
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Woodspliter

Member
Jan 25, 2020
131
Maine
Yeah I do like the floor unit, just a bit less efficient. The mitsubishi units are a nice bright white they will match the white trim work, may actually just complement the living room. Im just not sure about outdoor units I guess a little landscape can do the trick. The single zones are the most efficient and have more output than the same size multi zone units
 

stoveliker

Minister of Fire
Nov 17, 2019
1,224
Eastern Long Island NY
I ve been thinking about putting in a few singles in my 1100 Sq range one in the finished basement one in one living room kitchen area and a small 6k in the master bedroom. I've looked into the top three in my opinion mitsubishi fujitsu and daikin. I'm leaning towards the mitsubishi for the sizing and btu output. People are pretty put off by the look of the indoor units but I don't mind them I'd rather look a one box on the wall than put a bunch on holes in my floor to install base board

I have a mitsubishi system and I am very, very satisfied with it. I do not have the ultra low T system (being on Long Island where we get cold snaps but the sea moderates). Outdoor unit is MXZ-4C36NA2. Indoor units MSZ-GL18NA-U1 (and two 9 and one 6k units, instead of the 18k). 18k unit in the living/dining room with open kitchen. 6k unit in the basement mostly to dehumidify there (mitsubishi has a setting meant for that, where it keeps the temperature of the heat exchanger just below the room temp and keeps a constant low flow of air to maximize moisture condensation). I am not very enthusiastic about that; I still use the stand alone dehumidifier every now and then in summer to help the minisplit there.

I am quite surprised by how little energy they use, but that you can calculate for yourself using the COF.
What I'm even more happy about (having lived in the South with ducted central AC/heat) is the sound level. They are very quiet, both inside and outside. In fact when they installed the system, I opened a window when they started the outdoor unit, and I with my big mouth told them it was not working - being used to the big heat pumps from the South. It was working. You can't hear a thing. Only if you're within 3 ft can you hear a faint humming and the fan.

As I'm in moderate climate, with the stove, and an oil burning hydronic system, I'm only using the minisplit for heat when it's 35 or up outside. I may dial that down to lower temps when I get the hang of how many of my solar banked kWhs it uses. So far I use far less with it than I had expected. I looked also at daikin, but for me mitsubishi just looked better.

I don't care about the looks - though my better half does. However, getting AC here (when we had none, not even window units "b/c they look trashy", according to the wife) beats all complaints here.
Regardless, I don't think (apart from the very cold climate parts of the system of which I don't have knowledge) you can go wrong on any of these three brands.
 
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Woodspliter

Member
Jan 25, 2020
131
Maine
Yeah I agree a either one of the three would be good. I am going to be getting the low ambient temperature units. We woukd Like to be able to step away from the stove as it is our main heat source. So I think this combo will be great wood stove when it's super cold and heat pump the rest of the time. I love Bruning wood but I'd like to decrease our dependence on the wood stove
 

peakbagger

Minister of Fire
Jul 11, 2008
6,399
Northern NH
I ve been thinking about putting in a few singles in my 1100 Sq range one in the finished basement one in one living room kitchen area and a small 6k in the master bedroom. I've looked into the top three in my opinion mitsubishi fujitsu and daikin. I'm leaning towards the mitsubishi for the sizing and btu output. People are pretty put off by the look of the indoor units but I don't mind them I'd rather look a one box on the wall than put a bunch on holes in my floor to install base board

Its worth going to this site https://ashp.neep.org/#!/ and see what unit has the best cold weather performance.
 

Woodspliter

Member
Jan 25, 2020
131
Maine
Thanks peakbagger I have visited that site before kinds difficult to navigate. I looked on efficiency maine at the most popular rebates I know the mitsubishi probably don't have the best low temp heating temp and efficiency but seem to be a good overall unit. I'm just in the process of shopping a deal
 

peakbagger

Minister of Fire
Jul 11, 2008
6,399
Northern NH
I think it comes down to if you are doing a self install or paying for a dealer to do it.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,399
Northern NH
Not that simple but pick a brand, Mitsubishi for example then a type, single zone, non ducted wall placement, Now the tough part, for us folks in a cold zone you need to figure out your heat demand *you want at 5 degree F. and then enter that value. You should now be able to sort and get bunch of models that meet the criteria. Now switch to List view and you will get spreadsheet that you can sort. My suggestion is sort descending for the zone IV HSPF. That lists the most efficient heating units at top. If you are in heating dominant area HSPF is the heating efficiency, while SEER is the cooling capacity so you want the highest HSPF and may trade off a lower SEER.

If you are trying to get a utility rebate, they usually have minimum requirements for SEER and HPSF. You may have to submit a catalog cut in advance but it varies by utility.

*how big of heating load is the $1000 question. A standard manual J heating calculation can be done for a range of outdoor temps. As the temps drop the heating demand goes up, while a heat pump puts out less heat the colder it gets outside. Therefore if you have the potential for very cold outdoor temps like in Maine (minus 10 to 20) and you do not plan to have backup heat then you need install a lot of heat pump capacity. You also need additonal capacity if you are bringing a place up from one temperature to a warmer temp like a seasonal cabin. Manufacturers rarely list the COP at below zero temps but as the temp drops, the COP may drop to 1 which is the equivalent of electric heat. If you have high power rates and lower cost backup source its up to you to do the math for what temp makes sense to heat exclusively with heat pumps. The COP goes up as the outdoor temps increase. If you pick a particular model you can get the COPs for higher temps.

In my case and many others we have wood backup so we dont buy enough heat pumps to heat the house down to -20. We use the wood.I have a wood boiler so my threshold for my 12000 BTU Mitsubishi is around 20 degree overnight temps. As long as I set it and forget it, it should keep my close to 1200 square foot well insulated main floor heated. I have a second floor office that adds another 500 square feet and if I leave my doors open I can carry both floors with my single unit with temps over 30 F. My minisplit is 10 years old and current models have a bit more efficiency and marginally better performance at very low temps. I have not heard from many folks happy with their heat pumps performance at less than 0 degrees. The heat mine puts out at sub zero temps is only somewhat warm and it defrosts often. I have run mine for the last couple of days so it nice break for few days from feeding the boiler. Incidentally I can cool my main floor with this unit as long as I turn it on early on the hottest days. I have an older 7500 BTU minisplit AC only unit in my office that cover my cooling in summer. When it dies I will probably replace with a cold climate unit and be able to heat it with the minisplt more efficiently than heating it from a lower floor. BTW I have a solar system with net metering. I carry a surplus into the winter so its free heat and cooling in the summer.

I am not the only one with very cold condition mini split issues in Maine. I have mentioned in the past that I know someone who has sold Monitor vented kerosene heaters for decades (he was one of the first dealers in Maine), Monitor stopped production about 15 years ago so his business was ramping down keeping the ones out there still running. He and his daughter who runs the business are busier than ever as people are buying rebuilt units or Toyostove brand units to back up their minisplits during cold cold temps.
 
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EbS-P

Minister of Fire
Jan 19, 2019
1,005
SE North Carolina
I watched some of this video but not to the end and was surprised to see ceiling units for the zoned mini splits. The condensate plumbing was interesting to see. Not cold weather but a good example of how versatile these units can be. Evan

 
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