So... Anybody out there have any experience with cold climate heat pumps? Acadia claims to be able to produce anywhere from 25 to 45 thousand BTU's at an outdoor air temp of 0 F, and can provide close to the same at -30 F if you use the aux element in them. They are also claiming COP values that are "as good as geothermal". I'll include a link to their pretty chart at the end. We plan to build near Lake Placid, NY. The winter's are cold, long and cloudy, so passive solar doesn't look like a strong option. We plan to seal it tight and insulate it similar to Passivhaus, without actually getting certified. Does any one have general recommendations on systems to look at? We will get a pro to design and install whatever we go with, including Manual J and all that. I'm looking for an intelligent starting point for heating systems. We won't need the cooling component of a heat pump, so it seems like overkill, but will have the duct work anyway for an HRV, so radiant seems like overkill too. We shouldn't need a whole bunch of BTU's with R-40 walls and approx R-60 roof. Appreciate the comments! http://www.gotohallowell.com/images/stories/technicalinfo/AcadiaPerformanceCharts.pdf

Sounds like it is similar to the Daikin AC Altherma unit.

There are some discussions here on the Daikin unit and another one on the Acadia down under the Geothermal Heat Pump heading.

The COP of an air-source heat pump drops with outside air temperature and simply won't be as good as GSHP when the temperature is in the single digits or below. The heat load for a superinsulated house won't be very large in the first place, so whatever heat source you choose isn't going to cost you a lot to operate. If you are in a rural area and will have a well drilled anyway for house water, then GSHP can be a very good choice. In our case, there was no extra drilling cost for the GSHP, since it had to be drilled to its depth just to get adequate flow for house use. That depth turns out to support more heat load than the house will have, so the drilling for GSHP was "free."

Thanks for the replies. I'll check out the other threads. I didn't think it'd be in the geothermal thread so I didn't look there! I thought I'd read just about every thread here; I also didn't know that the same bore hole could be for drinkin' and heatin'. Thanks again!

You might jump in on this thread as well: http://www.greenbuildingtalk.com/Forums/tabid/53/aff/12/aft/77060/afv/topic/Default.aspx

(NRT.Rob is measuring the performance of the Daikin Altherma in Maine.)

I think the heating demands for Lake Placid will put any air source heat pumps (be it Carrier, Hallowell, Daikin, or anyone else) at a significant disadvantage compared to ground source heat pump.  At -4F, the Hallowell and Daikin units offer a COP of low 2's, and about 3's at 32F, so for Lake Placid I'd suspect a seasonal efficiency of a little lower than 3 (a guess).  This compares to a Climatemaster that can offer a COP of 3.7, as the ground temperature is relatively stable and is unaffected by outdoor ambient temperature.  A GSHP will be higher in cost even if you have space for trenching, and signifcantly more in costs if you're not in a rural area where you then have to drill vertically for the loop, and it's best to do a payback analysis depending on the options you have (NG if available, or propane vs ASHP vs GSHP) based on your heat loss loads, if cost is the primary concern.

The Hallowell unit looks interesting, as it offers a booster compressor, so I guess in a sense they've put in a 2 stage and a secondary single stage compressor to increase the outputs.  Daikin has an inverter pump, so it's a variable output (and not staged) compressor, so in theory it's more efficient, and it's certainly more so based on the engineering data, especially above the 0F mark, and IF the loop temps were kept lower then the efficiency really jumps up.  Daikin's total output is lower, but the Altherma is a hydronics based system, so it works well if you're trying to incorporate domestic hot water and/or radiant heat.  The Hallowell unit has a higher output, but it's a forced air system, so if you're after a forced air only system and/or you need a higher output, then it might look like a good fit.  I believe Daikin is coming out with a forced air system as well later on this year, but someone more familiar can correct me on this.

I'm biased towards Daikin as I have an Altherma installed and it's running well, but what steered me away from the Hallowell unit was based on some of the experiences that have been posted around, and I didn't want to take a chance.  Daikin is very reputable in markets other than North America, but is virtually unheard of here, so finding someone local with experience can be challenging (can be the same as Hallowell as well, since it's not that popular).

Victor
www.ecobuilthome.ca
A 4350 sqft Net Zero Energy initiative

Thanks for the response. I just checked out your website and your thought process for going ASHP. Now I'm going to dig through it more thoroughly. Love the Net Zero approach, but I don't think we could get there in Lake Placid with the long, cloudy winters. Sunny season isn't long enough to offset a winter's worth of energy use! We are going for max efficiency without breaking the bank. Hard to narrow down my options until I actually have the floor plan and a heat loss calc, but I've learned a great deal from these forums thanks to guys like you.

I'd imagine Lake Placid isn't very different than Toronto in terms of climate; we get the clouds too in the winter, but the production numbers for solar is seriously skewed towards the summer anyways.  The trick is to have enough roof space with optimal orientation to maximize generation.  At this point based on our initial numbers we're anticipating consumption somewhere in the 30000kWh to 35000kWh range for the year, and we'll be generating more than 50000kWh, so we could have cut our panel system size down significantly and still achieve net-zero.  I'll be putting up some initial numbers soon, but finding time to finish to blog is challenging given my day job and keeping an eye on finishing the house.

Brampton Hydro has a 20kW system with stats, you'll see that winter generation is a small fraction.  Lake Placid is IMHO doable as well, will depend on what your heat loss is like and how much money you want to sink into the solar.  It was easy for us because of the way the FIT subsidy works in Ontario, but I'd look into costs after subsidy in NY and see if it's feasible.

Victor
www.ecobuilthome.ca
A 4350sqft Net Zero Energy initiative