We discussed some similar issues in this thread:
https://www.hearth.com/econtent/index.php/forums/viewthread/40472/
I looked over the specs, and it looks like a nice, high eff unit.
The running amps will decline as it gets colder, but it will of course run more frequently. The heat output when running
will decrease even faster than the amps as it gets colder, so the cost per BTU of heat will increase. It is hard to be
more specific without large tables of the current draw versus temp that some mfrs supply. With HPs, it can be quite
hard to figure out in advance how much heat you will get and how much it will cost. For running cost, the factor that
they give you is the heating seasonal performance factor or HSPF = 10.1 which is an excellent score, BTW. It provides
a measure of how much heat you should get, divided by how many kWh it needs, averaged over a season, higher is
better. For AC, SEER is the same idea.
The units on HSPF are weird (kBTU/hr/kW), if you divide by 3.414, you get an easier to understand figure, seasonally
averaged coefficient of performance, SCOP = 2.96. This is basically your (seasonal average) efficiency relative to elec
resistance heat, 296%. In other words, if you use the fuel comparison calculator on this site, you could put in 300%
and your elec rate to get a cost per BTU to compare to other fuel costs.
The bad news is that SCOP/HSPF have to make assumptions about climate. The reference climate they assume is rather
close to that in Atlanta, Georgia. IF you live further north, YMMV, in fact, it will only be lower. It is summarized in a
paper at:
http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-413-04/
Bottom line is in my climate area, near New York City, the paper says my HPs SCOP should be 20% lower than the listed
value. After two years running my HP all season, I have verified this with my util bills. According to the paper, in Minneapolis
I would expect the figure to be 40% lower. So, operating costs if you ran it all season will depend on your climate, and you
can estimate them pretty well using the linked paper if you can find a climate proxy for New Brunswick.
I would guess that when it is above 0°C out it will put out something like the rated 20 kBTU/hr, and will be cheap to run.
Below -10°C, I would **guess** that the amount of heat could be half nominal (10 kBTU/hr), so it might not have nearly the
capacity of the pellet stove you are aiming to replace. Whether it makes sense to run it then depends on your elec cost, but
it seems that you would still need to have some supplemental heat during very cold weather.
If you are aiming to reduce your heating costs relative to all pellet heat, this unit will likely do that. But it seems unlikely that
it could provide all your heating needs in your coldest weather--keep the pellet stove handy for the first season.