I've decided not to. Mostly based on cost. I'm going to be using a Daikin split system variable refrigerant volume air-to-air heat pump. It has a COP around 3 at 10°F. Auxillary electric doesn't kick in until 10°F. Our design temp for heat is 9F, which means the heat pump will be extracting heat from the outside air pretty much all the time.

If this heat pump didn't have the performance capability all the way down to 10F I'd still be going geosource.

Only time will tell if it was a smart move or not.

Dmaceld, I'm in the same boat, looking at geothermal but cost is a serious factr. Someone recently placed a link to a new company in Maine that makes an air-to-air hp that can provide heat to -17 degrees F. You may want to look at www.gotohallowell.com. Dave

The Hallowell unit looks promising but there's three big differences between it and the Daikin. The Daikin can handle up to 8 indoor units with one outdoor unit. The Hallowell, one. There's about six configurations, and several sizes within each, for Daikin indoor units. Hallowell has only a couple it looks like. The Hallowell is a step variable flow system, meaning it has three compressor stages (two primary & one booster) with each stage either on or off. The Daikin has a continuously variable speed compressor, meaning the compressor can run at a very low speed and still pump refrigerant even when the demand is low.

The multiple choices of indoor units lets you pick what fits best from a regular ducted air handler to a small wall mount one room unit. You can also have the house zoned by individual units. This is a real consideration if you want to heat your garage. The IRC prohibits any interconnection between the living space and garage which means you have to have separate heaters for each. With the Daikin one outdoor unit supplies both. I'm using a 12,000 Btuh wall unit in the garage. The outdoor unit will supply it by itself if its the only one that needs to be running.

The continuously variable feature means the compressor can run more hours and adjusts its output to the demand. Contrary to common first thinking, equipment lasts longer the more it can run continuously. Starts and stops are hard on compressors. An electric motor that can run continuously will last longer than one that starts and stops in terms of runtime hours and possibly even in terms of calendar time.

I know this might sound like a sales pitch, but if it does it's because I've bought into it and those are the reasons I'm going with the Daikin. Plus, my nephew HVAC contractor is sold on them and wants to install one in my house.

There's no doubt the Hallowell system looks good, and may very well be the best choice in certain situations. In fact, I told my nephew a couple of weeks ago he needs to look at them as a possible product line.

The capability to put out heat at lower temps is a definite plus for the Hallowell, but that's a capability I don't need.

They use the ECR system, correct?

The EarthLinked system is the one with the most proven refrigerant controls. Just make sure the one you use is ARI and ETL certified.

EarthLinked was the original ECR unit. It was ECR Technologies, Inc., not to be confused with ECR Industries. Now ECR Technologies, Inc. has changed their name (trying to avoid any confusion with ECR Industries) to EarthLinked Technologies, Inc.