Advancements in cold climate heat pump efficiency.

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Brian26

Minister of Fire
Sep 20, 2013
606
Branford, CT
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

As much as I love burning wood as well I am pretty much using them practically 24/7 here. I really only burn in severe cold outbreaks. Its just so easy to set the units to 70 with zero work required. Building small fires during shoulder season sucks. Way easier to run a split that costs pennies per hour to run.
 

Brian26

Minister of Fire
Sep 20, 2013
606
Branford, CT
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

I have a floor unit and a regular wall unit downstairs. The floor console in heating mode is vastly superior to the wall unit. It can direct air in 4 directions out both the top and bottom. In heating mode I usually have it go out the bottom on the floor. A huge advantage with the floor units is they are drawing in the cold air down low along the floor. Wall units are way up high drawing in the warmest air up by the ceiling. Ideal for cooling but not heating.

I shot mine with my FLIR. You can see the nice heat it sends out along the floor.
flir_20191102T090621.jpg
 
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stoveliker

Minister of Fire
Nov 17, 2019
1,477
Eastern Long Island NY
I have a floor unit and a regular wall unit downstairs. The floor console in heating mode is vastly superior to the wall unit. It can direct air in 4 directions out both the top and bottom. In heating mode I usually have it go out the bottom on the floor. A huge advantage with the floor units is they are drawing in the cold air down low along the floor. Wall units are way up high drawing in the warmest air up by the ceiling. Ideal for cooling but not heating.

I shot mine with my FLIR. You can see the nice heat it sends out along the floor.
View attachment 273937
Nice pic! My wall unit (high up) can also direct up (well, parallel to the ceiling), down, and left and right.
In my case they work very well, also for heating. Obviously I don't have a comparison as I don't have a floor unit (which would have interfered with the hydronic baseboard I also have).
 

Highbeam

Minister of Fire
Dec 28, 2006
19,134
Mt. Rainier Foothills, WA
So far it seems mainly Highbeam that strongly objects to the look of the wall units. They don't bother me.

I'm coming around to the look. At some point, as with the princess stove you strongly object to, the performance benefits exceed the aesthetic drawbacks.

Myself, I've been looking at the MrCool DIY units again. The project is almost too easy with electrical being almost a bigger challenge than the actual heat pump.
 

semipro

Minister of Fire
Jan 12, 2009
4,058
SW Virginia
Myself, I've been looking at the MrCool DIY units again. The project is almost too easy with electrical being almost a bigger challenge than the actual heat pump.
We installed a Mr. Cool Universal unit in July and I'm pretty impressed so far. I need to post a review. If anyone has any specific related questions I can probably provide some insight. For instance, I discovered that while the compressor and exterior fan are variable speed the one in the air handler is not. However, it does run at a different non-variable speed depending upon whether you're running in the 2 or 3 ton mode. I was also initially unimpressed with the plastic exterior fan until I realized that the way it's shaped is one of the reasons the unit runs so quietly. I'm assuming it would be tough to get the same complex shape from a metal fan.
 

Highbeam

Minister of Fire
Dec 28, 2006
19,134
Mt. Rainier Foothills, WA
We installed a Mr. Cool Universal unit in July and I'm pretty impressed so far. I need to post a review. If anyone has any specific related questions I can probably provide some insight. For instance, I discovered that while the compressor and exterior fan are variable speed the one in the air handler is not. However, it does run at a different non-variable speed depending upon whether you're running in the 2 or 3 ton mode. I was also initially unimpressed with the plastic exterior fan until I realized that the way it's shaped is one of the reasons the unit runs so quietly. I'm assuming it would be tough to get the same complex shape from a metal fan.

The standard wall units from mr.cool MUST have their refrigerant lines poke through the wall on the right side of the unit which is a problem for me. So I became discouraged and started reading about the universal central one again.

I watched their video installing/retrofitting that unit in an old house in North Dakota and it sat there at -24 degrees making full output to keep the home above 70. Pretty impressive stuff. We barely ever get to single digits here.

I think the blower speed on a ducted unit needs to be high enough to always keep flow to all of the vents on the duct. So if it were to roll really slowly like a wall unit there might be some rooms that get no heat.

I'm honestly afraid of ductwork. I have plenty of space in the attic to run the very simple ducts to just a few central rooms but I don't know how to fab up the return air filter, and the take off on top. It seems daunting.
 

sloeffle

Minister of Fire
Mar 1, 2012
851
Central Ohio
As much as I love burning wood as well I am pretty much using them practically 24/7 here. I really only burn in severe cold outbreaks. Its just so easy to set the units to 70 with zero work required. Building small fires during shoulder season sucks. Way easier to run a split that costs pennies per hour to run.
Can you expound on how many pennies per hour you are spending to run your mini-split ? And how many BTU's you are producing ?

For example - I have a Waterfurnace 5 series ( Envision when I bought it ) and it uses 2.2kW when running on the first stage. My installation method is via ground loop so my COP is around 4.4 according to the Waterfurnace manual. At my current electric rate it costs me 35 pennies per hour to run and it produces 31k BTU's.
 

Brian26

Minister of Fire
Sep 20, 2013
606
Branford, CT
Can you expound on how many pennies per hour you are spending to run your mini-split ? And how many BTU's you are producing ?

For example - I have a Waterfurnace 5 series ( Envision when I bought it ) and it uses 2.2kW when running on the first stage. My installation method is via ground loop so my COP is around 4.4 according to the Waterfurnace manual. At my current electric rate it costs me 35 pennies per hour to run and it produces 31k BTU's.

I have net metered solar so I don't actually buy the electricity. Decent cold climate mini splits though average around 1kw per ton of output with COP's around 3.5-4. I'm in CT where electricity is expensive around .24 kwh. If I did have to buy the electricity it would cost about .60 cents/hr to run both my 12 and 18k btu units at full output. They rarely ever run anywhere near full output though. I have electricity monitors on both mine and even on the coldest days I never use more than 15 kwh's day. That's for both units combined. In the 2 winters I have had them I have never used more than 500 kwhs a month. They provide probably 98% of my heating load.

I read that air source heat pumps are pretty much on par with geothermal now. Minus the expensive ground loops. I self installed both my splits for less than $2500.
 
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EbS-P

Minister of Fire
Jan 19, 2019
1,165
SE North Carolina
My 3 ton heatpump is now 11 years old. Back then it was top of the line installed right before we bought the house. I just looked at the data sheet. COP47 is 3.9 at 36k and COP17 is 2.7 at 21k. All at about 2.3 kW. That’s not cold weather performance but it never gets and stays cold here. My rough math I have been using and confirmed was about on average 12 12kw hrs a day at 0.12$ kw hr. Or about 50$ a month.
This is a package unit and even today you can’t get a package unit that is more efficient. Hence why you are seeing more mini splits even here in the southern part of the US.
 

sloeffle

Minister of Fire
Mar 1, 2012
851
Central Ohio
I read that air source heat pumps are pretty much on par with geothermal now. Minus the expensive ground loops. I self installed both my splits for less than $2500.
If I was doing the same installation today I would probably choose a ASHP over geothermal due to the COP's being about the same for heating. If I was in a cooling dominated climate I think geo is still the way to go. Not unless you are heating / cooling a big house I don't think the ROI is there anymore for geo over ASHP. The two nice things about geo are, you don't have to listen to the compressor outside of the house run, and at least in my situation the cooling is dirt cheap. I spend about $5 - $10 a month ( .16kWh ) to cool my house and make hot water during the summer. :) I don't think you can do that with a conventional unit.

To give you some perspective on price, I paid 17k 10 years ago for my system. I however got a 1k back from the electric company and the government at that time had a 30% or 33% tax credit. After those two "rebates" it actually brought the prince inline with a bid I got for Trane ASHP / propane furnace. That's why I went the geo route. I got one geo quote that was as high as 26k. I would love to know the markup on a quote like that.
 

Brian26

Minister of Fire
Sep 20, 2013
606
Branford, CT
These cold climate splits also have some incredible cooling performance. I have electricity monitors and I pretty much left both my splits set to 72 for the month of May. It was warm here with many days in the 80s and some 90s. Total electricity consumption was only 100 kwh! Its incredible watching the electricity monitor of the unit drawing less than 100 watts and blasting out cold air.

I have a 30.5 Seer 12k gree Sapphire and 24 Seer 12k Midea Premier. The Gree carries most of my cooling load. This thing has some insane cooling efficiency. At its minimum capacity at 95 degrees it has a COP of 10.62 and is only drawing 80 watts.

Screenshot_20210528-063638_Chrome.jpg Screenshot_20210528-062127_Monitor.jpg
 
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ABMax24

Minister of Fire
Sep 18, 2019
1,048
Grande Prairie, Alberta, Canada
These cold climate splits also have some incredible cooling performance. I have electricity monitors and I pretty much left both my splits set to 72 for the month of May. It was warm here with many days in the 80s and some 90s. Total electricity consumption was only 100 kwh! Its incredible watching the electricity monitor of the unit drawing less than 100 watts and blasting out cold air.

I have a 30.5 Seer 12k gree Sapphire and 24 Seer 12k Midea Premier. The Gree carries most of my cooling load. This thing has some insane cooling efficiency. At its minimum capacity at 95 degrees it has a COP of 10.62 and is only drawing 80 watts.

View attachment 279119 View attachment 279120

That's really cool (pun intended), and impressive performance curves. I really do have to question that COP of 10.62 however, I'm thinking there is some error in that number, I thought theoretical maximum COP was somewhere around 8. In fact I have to question all those min values, they all seem overly optimistic to me.
 

EbS-P

Minister of Fire
Jan 19, 2019
1,165
SE North Carolina
That's really cool (pun intended), and impressive performance curves. I really do have to question that COP of 10.62 however, I'm thinking there is some error in that number, I thought theoretical maximum COP was somewhere around 8. In fact I have to question all those min values, they all seem overly optimistic to me.
I have seen these number on this unit. I just can’t imagine the case where they are real world repeatable numbers. For the sole fact that if the tech was out there why is Mitsubishi not offering anything similar? I think there is evidence that they are very efficient but a COP>10..... if it was true that’s a gold mine, or a loophole, rounding error in their favor on the standard test like the flow meter only measures in units of 50 cfm and whole degrees Celsius. When turned way down those rounding errors could be used in your favor. That said if I could be assured that the warranty would be honored I would be very tempted to install one.

Evan
 

maple1

Minister of Fire
Sep 15, 2011
10,789
Nova Scotia
Nice pic! My wall unit (high up) can also direct up (well, parallel to the ceiling), down, and left and right.
In my case they work very well, also for heating. Obviously I don't have a comparison as I don't have a floor unit (which would have interfered with the hydronic baseboard I also have).

Just as a general FYI to anybody reading, a floor unit can be installed above baseboard. Ours is. They are called floor units but are still fastened to the wall. A bit of a misnomer. You could put one anywhere on a wall you wanted, but they are at their best when heating when mounted way down low. As Brian's IR pic shows. A very big and very noticeable advantage over wall mounts up at the ceiling.
 

Woodspliter

Member
Jan 25, 2020
131
Maine
Just as a general FYI to anybody reading, a floor unit can be installed above baseboard. Ours is. They are called floor units but are still fastened to the wall. A bit of a misnomer. You could put one anywhere on a wall you wanted, but they are at their best when heating when mounted way down low. As Brian's IR pic shows. A very big and very noticeable advantage over wall mounts up at the ceiling.

Id like to know where maple is getting his information from, all the research ive done on heat pumps the wall mounted uints have better Seer and Hspf ratings than the floor uints. Is there something im missing?
 

stoveliker

Minister of Fire
Nov 17, 2019
1,477
Eastern Long Island NY
I think that injecting heat at floor level is more efficient in heating (or experiencing a good climate inside) as compared to injecting heat up high.

Of course the trade off is that cooling in summer works less well. So it's important to assess what is more important for your situation.
 

maple1

Minister of Fire
Sep 15, 2011
10,789
Nova Scotia
Id like to know where maple is getting his information from, all the research ive done on heat pumps the wall mounted uints have better Seer and Hspf ratings than the floor uints. Is there something im missing?

Living with one unit of each type of the same btu ratings. The floor mount feels warmer. The air currents from a high up wall mount can lead to less comfort. Especially when they're defrosting. And I think they sometimes can create a small gradient so it is cooler in the room down low where you're sitting maybe depending where you're sitting. I dont think I compared their spec sheets but now you've got me curious.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,461
Northern NH
I heat both a main floor and part of a second floor with single minisplit. I think the standard high mount gets the heat to the second floor quicker.
 
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maple1

Minister of Fire
Sep 15, 2011
10,789
Nova Scotia
I heat both a main floor and part of a second floor with single minisplit. I think the standard high mount gets the heat to the second floor quicker.

Yes, I agree. Our living room high mount points toward a doorway, outside of which is a landing at the bottom of our stairway to the second floor. It is noticeably warmer at the top of those steps than it is in the room the unit is in, down low and off to the side of it. Which is where our love seat facing the TV is . Heat rises, which is the simple reason for the differences in high mount vs. low mount overall feelings of comfort when heating .
 
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Brian26

Minister of Fire
Sep 20, 2013
606
Branford, CT
Id like to know where maple is getting his information from, all the research ive done on heat pumps the wall mounted uints have better Seer and Hspf ratings than the floor uints. Is there something im missing?

Not the case with my Midea floor console. My floor console has better efficiency numbers and a lower min capacity than the high wall unit on the same outdoor condenser. I think the coil surface area is larger and more efficient on the floor console as its square.
Screenshot_20210605-094444_Drive.jpg

20191023_064534.jpg
 
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MikeT2

Member
Jan 23, 2019
21
Vermont
Question for the group-
I currently have a propane boiler and a gasifier wood boiler on the same system in Vermont. Wood boiler runs in the winter and propane heats the DHW in summer. I have two wood stoves for shoulder season usage and supplemental. I have radiant floors except for the second floor which has two smith power radiators.
The wood boiler is rated at 140,000 BTU and handles winter except for really bitter cold stretches (below zero times) and then a wood stove is lit off to help.
I believe the 140 degree ASHP would work quite well for the shoulder seasons and DHW for summer. I can get a grant of $6500 towards a single ASHP.
My thinking is to replace the times the wood boiler is in use, I would need two ASHP units. Not going to do that. If I got just one, would it be too undersized to work in the shoulder seasons?
I would consider getting a ASHP water heater, but they do appear to be quite expensive for what you get unless I am wrong there.
I thought about a few mini-splits and I can get a $650 rebate but this appears to be a very large expense
Thanks!
 

maple1

Minister of Fire
Sep 15, 2011
10,789
Nova Scotia
Question for the group-
I currently have a propane boiler and a gasifier wood boiler on the same system in Vermont. Wood boiler runs in the winter and propane heats the DHW in summer. I have two wood stoves for shoulder season usage and supplemental. I have radiant floors except for the second floor which has two smith power radiators.
The wood boiler is rated at 140,000 BTU and handles winter except for really bitter cold stretches (below zero times) and then a wood stove is lit off to help.
I believe the 140 degree ASHP would work quite well for the shoulder seasons and DHW for summer. I can get a grant of $6500 towards a single ASHP.
My thinking is to replace the times the wood boiler is in use, I would need two ASHP units. Not going to do that. If I got just one, would it be too undersized to work in the shoulder seasons?
I would consider getting a ASHP water heater, but they do appear to be quite expensive for what you get unless I am wrong there.
I thought about a few mini-splits and I can get a $650 rebate but this appears to be a very large expense
Thanks!

What exactly are you referring to by '140 degree ASHP'?
 

maple1

Minister of Fire
Sep 15, 2011
10,789
Nova Scotia
The newer Air source heat pumps can produce 140 degree water

Ok. Lots of variables to the questions in your first post that go way beyond the output temp of the ASHP alone. You'd need to know its overall btu output and at what inlet temp or dt. E.g., how many gpms would it flow at what dt with inlet temp of say 100 or 120? A cold inlet temp say from heating dhw, of say the 60-70 area, would be capable of pulling more BTUs out of the heat pump. Then there's your distribution system. Radiant floors dont need as high input temps as say baseboard but there is still an overall btu requirement for a given outside temp or overall heat loss. (Plus DHW demand). If things match up on each side, then maybe? But there's also equipment costs to factor in and paybacks. No idea how much the heat pumps cost that you're speaking of. They haven't really hit where I'm at yet. That sounds like a real fat grant figure, are you sure that's not for geothermal?