This is true. But your ROI has to include how many days there are in a year where really low temperatures exist. A lot of people use the principle of using the least expensive technology available that will cover 90 to 95 percent of their needs before going to a much more expensive technology that will cover 100 percent of their needs. I'm not one to decide which is best but I think both philosophies have merit.

How long you stay in your present house will enter into that equation.

We currently don't have an inside thermostat, using weather compensation to adjust the buffer tank temperature for the UFH.
Whilst we aim for 20C (68) the house does fluctuate depending on solar gain and occupancy in a room.
House is heated 24/7 to the same temp by a tiny ASHP.

Since I'll be 68 this month, I don't plan on living in this house more than another 10 or 15 years.. :p

This is just a freak cold spell. Right now, temperatures are normal in Greenland.
Record Cold Temperatures Are Projected to Hit Much of the U.S. | TIME.com

While the U.S. as a whole has warmed by about 1.3º F (0.71º C)over the past 100 years, winter has seen the fastest warming. Winter nights across the country have warmed about 30% faster than nights over the whole year. Since 1912, the coldest states have warmed nearly twice as fast as the rest of the country. In a warming world, winter loses its sting.


This kind of cold snap should be a rarity, in the coming decades.
If my ASHP Sanyos wear out, I'll buy more of the same.

Sounds really sensible if you are in California right now and the weather is fairly pleasant.

If you had three Sanyos, or maybe four Sanyos you might be able to ride out this foul streak with ease.


But the kind of weather you are now facing is the situation that Ground source Heat Pumps were made to handle well.


Twenty-five feet down in the ground, the temperature is around 47 degrees F, not -4 degrees F.

You may decide that the technology does not fit your budget, or that you'll never live long enough to pay it off... but physics will not be denied.

-AC

The cost of digging for the ground loop is a BIG factor in determining payback time. If you do it when the house is built and the construction equipment is on site, the upfront expense isn't nearly as much as a retrofit install.

Good point. If I had to dig the ground loop GSHP on a preexisting house as a retrofit in Mass I'd stick with Xringer's position. I'm 60 myself so I can identify with an ROI that may not be optimistic. I'm not the young buck AC is.:eek:

Just because I'm 69 and I dug my loop field by hand doesn't mean I expect anyone else to get up out of their lounge chairs.

-AC

Here's our schedule, it's been modified to 70 for wake and 55 for day.

http://ecorenovator.org/forum/attach...2_191711_0-jpg

I live on the north side of a 200 foot hill that's made out of solid rock.
The soil here isn't very thick, and it's fill with boulders the size of VW Beatles..

Digging anything over 8 or 10 feet deep is going to require explosives. :eek:

We keep the temperature around 65 degrees, our 3-Fujitsu's air source heat pumps (two 1-ton units and one 1.5 ton unit) have been able to provide us with all of our heat. -3 degrees has been the coldest temperature that I have witnessed this month. We live close to Gillette stadium where the New England Patriots play their home games in Foxboro, Massachusetts.

Our upstairs heat pump is set to 60/62 degrees, downstairs we have two heat pumps (1-ton and 1.5 ton) and the 1.5 ton is set to 70 degrees and the 1-ton is set to 62/64 degrees. 1840 square foot cape style house built in the late 1970's.