Outside air-sourced heat pump compressor

Air-sourced heat pump inside "head"

If you are not familiar with what a heat pump is, you might start by reading this U.S. Department of Energy article on Heat Pumps, and this Heat Pumps 101 from Alaska Heat Smart.  You might have heard they don't work well in cold climates.  If they work in Alaska, they ought to work in northern Wisconsin.   Mechanically, heat pumps are similar to our refrigerators and freezers.  They can cool in the summer and when the flow is reversed they can heat in the winter.

So, we opened up the topic to our community and asked for help in sharing experiences related to a heat pump installation.  We asked about brand names, installation contractors, good and bad experiences.  Below are our first entries.  If you want to join our community forum, ask a question or submit your experience or a reply, contact us at [email protected].  

Question/concerns from Clair, City of Ashland:
 
1. Can Cheq Bay Renewables provide information on options for electrification of existing homes?  For example, our natural gas furnace is of an age where it may need replacement any time. Attempts to research energy efficient electric furnaces (i.e., heat pumps that work in cold climate, etc.) are difficult and confusing. It is very hard to figure out what contractor to talk to locally.
2. Can you provide contact info for contractors who can do a valid efficiency assessment of a home (adequacy of insulation, sources of heat leak, etc.)

I worry that there may not be adequate sources of this info in the area, but I hope I'm wrong on that part!
 
Clair
 
 
CBR Reply:
 
We are not experts on heat pumps but know of several that have recently been installed in the area.  We will put the question out to the community and see if they may have some answers.  And while we are at it, we will see if anyone can recommend a local company to perform an energy audit.


 
Community Replies:
 
Reply from Mike, Bayview Township:
 
I have a 36,000 BTU Mitsubishi air source heat pump with two indoor air handlers (also called "mini-splits" or "heads") to heat 1,850 square feet divided between two levels.  The contractor was Twin Ports Heating and Cooling in Superior (ask for Joerg Rosebrock, HVAC consultant).  My system has an optional de-icing mechanism that allows it to heat down to -13 F.  The standard northern climate heat pumps only heat down to 5 F.  When it's that cold, though, our woodstove does most of the heating.  We still have the original baseboard and slab heating system for backup, and our windows give us amazing heat gain on sunny days, though I'm sure they leak as much heat on cold nights.  I also have a 6.5 kW rack of solar panels, which is why I wanted to stick with electric heat.
 
So far, we like the system.  It makes different noises than forced air, but it's still quieter.  My wife really likes the smell of the air coming from the air handlers, since it is filtered and doesn't have the odd smells that come from ductwork or baseboard heat.  If I crank it, it will flood our house with more heat than we can stand.  It runs at half to a quarter of the cost of the baseboard heat, depending on the outside temperature.  I've had to learn its quirks, though, so it's a good thing to have a sub-forum like this to help folks know some of the details of living with a heat pump.  I've made it into a lifestyle, trying to figure out how to make it work most efficiently, but I'm a wannabe geek about such tech stuff.  You could just set your temps with the timer and not really fuss with it much.  The filters need to be vacuumed every two weeks.
 
Mitsubishi has excellent tech help available by phone.  Their user manual is an OK reference but leaves a lot out.  I also looked into Fujitsu pumps, and their systems seemed comparable to Mitsubishi.  If you are handy and you know how these systems work, you can buy them online and install, yourself, and probably save a lot of money.  However, the installation has to be done right, or problems will ensue.  I interviewed contractors who seemed to know less than me about how they work, and a couple proposals that were made would have required modifications if I had accepted them.
 
I also tried to find a company to do an energy audit with a blower door.  There were two in this area at the time, two years ago, and neither returned calls.
 
Best!
 
-mike
 
 
Reply from Sam & Eileen, Bayfield Township:

We became interested in air source heat pumps after attending a CCL discussion series in 2018 about “electrifying everything” and installing a mini-split ductless ASHP system in their home was mentioned.  Our wood stove was our main heat source, with a 3-ft electric baseboard heater in the bathroom & a 6-ft section in the kitchen/dining area.  We hardly use the baseboard, but installed them to keep pipes from freezing if we needed to be away from home.

For us, an ASHP wasn't a hard choice. We know we can't haul & split wood forever.  Living in the country, we don't have access to natural gas. We weren't interested in propane, & all the digging for geothermal seemed too involved. We had already bought shares in the Bayfield Electric Co-op solar garden.  A CCL member had already done research on ASHPs & recommended Fujitsu as a brand that could handle temps down to -15F; also, they were very satisfied with installation by Tim & Pat Cook (father & son) from Kleen Air in Washburn.  I did call around, though, talking to Blakeman & also Frostman Heating & Cooling--at that time, both said that Fujitsu was the only brand of ASHP they installed. Blakeman said they had installed a 9-head Fujitsu system at the Rittenhouse.  When I spoke with them, they said they hadn't experienced a full winter yet, but were pleased with performance at that point.

We went with Kleen Air, & the Cooks were very easy to work with--good communication, efficient.  They installed a 24,000 btu outdoor unit (AOU24RLXFZH) & then 2 wall-mount indoor units:  a 7000 btu/h (ASU7RLF1) upstairs in our bedroom & a 15,000 btu/h (ASU15RLF1) downstairs over the kitchen sink.  Their supplier in Duluth (Ferguson Plumbing) specified the sizes, based on a sketch of our layout (~2000 sq ft heated space, not including basement, greenhouse, N entry area). Their quote of $7000 was what we paid them on completion. They lined up an electrician (Sarver Electric) to bring power from the pole to the unit ($410) via conduit in a shallow trench that Sam dug.  We did receive a $300 rebate from Bayfield Electric Cooperative.

The system works quite well for us, although we still enjoy using our wood stove--we like the coziness of that direct warmth to gather around in the living room, put on a kettle for hot tea anytime, etc. on the stovetop. We do have cold spots in the house, but usually have the thermostat set so the house temp is no lower than 60-65F & then supplement with our woodstove.  We were very interested to learn, Mike, that you installed a much bigger capacity for a slightly smaller space!  I think we may have indicated to Kleen Air/Ferguson that we would continue to also use the wood stove as long as we were able.  But we could turn up the heat on the ASHP & use our electric baseboard in the future--after installing a 6.2 kW solar system (Next Energy Solution), we still had >2000kwh banked credit with Bayfield Electric Cooperative at the end of March (this included our solar garden credit, with annual zero out day May 1).

There is some noise.  In talking to tech help at Fujitsu, they recommended that the outside unit be mounted on concrete above winter snow levels; they said mounting to the wood-framed portion of a house would transmit vibration (ours is balloon-framed), but that shaking would not be a threat to a wood structure.  Since we didn't have a concrete basement wall high enough off the ground or get organized to install a separate concrete pad before the time window Kleen Air had in their schedule, we went with the standard bracket shelf mounting on the side of our house that they could offer, which does have some rubber buffer between the unit & shelf. The bottom of the machine is mounted a little more than 2' above ground level, which seems sufficient.  The roof overhang on the house does protect the unit from snow above & nearby lilacs prevent high drifts in front of it.  Sam wishes the unit were quieter; I think of it as the sound of heat so don't mind. If possible, we would suggest a separate concrete base with framing to hold the unit above the snow, as well as a roof to protect it from above, to avoid mounting on wood house framing. 

Clair, you bring up a good point about the importance of an energy audit.  We had one performed by Kevin Myers (715-520-3803) of [email protected].  He was referred to us by KV Tech, after they put us on a waiting list for an audit & later called to say their own time frame would be a year or so.  Kevin did a blower door test & gave us a CD with the infrared imaging detailing recommendations to address the many leaky issues in our 1920s remodeled house.  We felt he was very thorough & practical in his suggestions.

Best of wishes to you all!  Thank you for the discussion & chance to learn more about energy efficiency!
​
Eileen & Sam
 
 
Reply from Bill, City of Bayfield:
 
I am happy to share my experience with our ASHP system. We were adding a ground-floor bedroom, bath, and attached garage to our 1900-ish house in Bayfield, and a mini-split system seemed an obvious choice: the existing house has a boiler with big upright radiators that was not possible to zone; we wanted AC capability; and I was taken by the “electrify everything” argument (that has only gained momentum in recent years). 
 
Our contractor was Kleen Air of Washburn. Our whole project was rushed and Tim and Pat really saved the day by scrambling to organize the system and install the main piping and wiring such that the construction sequence could keep moving along. The system is a Fujitsu 36,000 BTU/hr. outdoor unit and three indoor heads. The outdoor unit, the low-T option, is spec’d to -15°F. We mounted it to the frame of the addition, something I didn’t want to do because of the potential for vibrations. But the outside was far from final grade and I didn’t want to risk damaging the unit when this work was finally completed. I am still scheming to transfer the unit onto a pad on the ground — while the vibration is not particularly annoying, I imagine that the sound could be even less if the unit was better isolated.
 
One of the three heads is in the new bedroom and it handles that with ease. The largest (18,000 BTU/hr.) serves the dining room, kitchen and living room. These three spaces are about 950 sq ft, connected by wide (~6’) archways. The head in the dining room has trouble pushing the warm air out into the other two rooms, leading to uneven heating and, I think, cycling of the outdoor unit. These problems are reduced by running a ceiling fan in the dining room in the “summer” mode, that is, blowing directly downward. But you’ve got to slow or turn off the fan if you want to comfortably use the dining rooming table. In retrospect we should have installed two smaller heads, one in the living room and one in the dining room. Had the construction sequence not been so rushed I might have thought to explore this.
 
A specification on the outdoor unit is that it can modulate its output (this is a key efficiency feature of modern ASHPs, I think) if it has a load greater than 12 MBH. Without good air exchange across the three rooms that the 18 MBH head is serving, though, this demand is not met and the system cycles (I think). Fujitsu customer service by email was useless on these questions, with brief responses consisting of sentence fragments. So maybe if we had two heads in the original main floor and a smaller outside unit the system would run more steadily, but at the risk of not meeting out needs on the coldest days. Or maybe my system should have involved two outside units. Lots of speculation in this paragraph on my part!  
 
The system made heat down to -12°F this past winter, at which point I switched to the boiler system. We also installed a small gas fireplace in the living room that evens out the temperature there and provides nice ambiance (at the cost of guilt over bringing more gas infrastructure into the world!).
 
Mini-split systems all seem to be operated by handheld remote controls, a system that is old school, especially in this day of smart homes. I am anxiously awaiting delivery of controllers for the system, just introduced by Mysa, a company that makes smart (specifically Apple Homekit-compatible) line thermostats. I have three of these controlling small resistance heaters and they are very nice.
 
I also research ASHP water heaters, but concluded that they don’t make sense in our climate. I was surprised to see that ASHPs are even showing up as options in electric cars.
 
Bill