August 16, 2008
Ground Sink Heat Pump Demand Surges
Ground sink heat pumps are surging in popularity in the United States as the alternatives become much more expensive.
Though no comprehensive survey of the heat pump sector exists, Energy Department statistics on units shipped tell a striking story. In 2003, system manufacturers shipped 36,439 units. In 2006, the last year for which data is available, manufacturers shipped 63,683 units.
Bridgette Oliver, marketing and communications manager for ClimateMaster in Oklahoma City, the nation’s largest manufacturer of ground-source heat pump equipment, confirmed a rapid rise in sales. “Between 2005 and 2007, our revenue increased by 200 percent,” she said. “Our employees increased by 176 percent.”
Those are pretty small numbers when compared with the number of buildings constructed per year and even more so when we consider all existing housing stock.
One ground sink heat pump installer in Seattle claims a 5 year pay-back period.
There is a catch. A geothermal system costs more to install. Maloney believes that may be the reason why geothermal systems haven't become widely popular.
"Our costs are usually about 50 percent more than conventional equipment," said Maloney, comparing a geothermal system with a high-efficiency furnace, hot-water heater and air-conditioner installation. "That 50 percent you'll generally see back in about five years."
He estimates the cost of providing a conventional natural-gas system, including a furnace, air conditioner and water heater, might be $10,000. A ground-source geothermal system probably would cost $15,000 to $20,000, he said.
The payback period depends on what you are using now. If you are using oil the payback of a heat pump is a lot shorter than if you are using natural gas for example. Also, your weather matters as well. The capital costs pay back more rapidly if you have a lot of days where you need central heat or central cooling. Plus, you have to consider efficiency of each heat pump model. They aren't all the same in efficiency.
This comparative heating cost calculator will let you figure out how much you could save by switching to a lower cost way of heating.
I truly wish more houses would use that technology. 5 years is nothing compared to the average life of a heating system, and it's probably going to get shorter as fossil fuels become more expensive.
Sounds like this might be a better use of subsidy dollars than spending them on solar panel subsidies.
In some areas the ground sink produces very impressive results. My step-brother has had a really first class ground sink heat pump arrangement for about 20 years. I think he said it went down 80 feet into a water table. The house is near Wichita and was built for a contractor who had spared no expense for his own home.
Economics is open to argument from all sorts of angles. But subsidizing solar when demand exceeds supply tends to keep prices up. If solar manufacturing improvements are expected to reduce price steeply within a few years then subsidies for the ground sink heat pumps now might actually spur solar price declines.
Energy cost savings are not totally comparable between the approaches. A heat pump can only cut costs when it runs. In mild climes it may do nothing for months while solar would produce usable electricity nearly every day. In extreme conditions, such as an Arizona summer or Canadian winter, the improved heat pump could be saving money up to 24 hours a day.
And heat pumps aren't going to put unneeded power into the grid on sunny days. So infrastructure costs count too.
I think ground sink heat pumps reduce fossil fuels use more per dollar spent than do solar panels. However, the argument for the solar panels is that the demand feeds research and development to develop cheaper solar panels. In the long run one can argue that will have a bigger impact. Though at this point we probably have enough politically created demand for solar panel to catalyze the development of cheaper methods of PV fabrication.
To maximize the impact of solar, wind, and nuclear as energy sources that displace fossil fuels we need to shift more energy demand to electric. Heat pumps do that. So lots of ground sink heat pumps installed in the short term will be there to use solar energy once solar energy becomes cheap enough.
Heat pumps are underused given their return on investment. So incentives for their use definitely produce a big return.
My guess is that greater incentives for heat ground sink heat pumps (and air heat pumps in milder climates) will bring bigger benefit than incentives for solar panels.
Heat pumps are OK in California and the south where it does not get seriously cold. In the midwest and northeast, they are not a big winner.
Ground sink heat pumps have the lowest energy cost in the Midwest and Northeast (and Canada of course). Air heat pumps have limits on how far north they make sense. At some point the higher costs for drilling or digging to put in the ground sink heat pump piping makes more economic sense.
> Heat pumps are OK in California and the south where it does not get seriously cold. In the midwest and
> northeast, they are not a big winner.
This is surely wrong. Ground source heat pumps make more economic sense the COLDER the weather gets. 10-15 feet below the frost line, the ground remains 50-55 deg F all year round. Thus it requires only a delta of 20 deg F in supplementary heating to make the house comfortable. This is a tremendous savings, compared to the energy required to heat the house when the outside ambient temperature is -15 deg F.
A ground source heat pump typically has a COP (coefficient of performance) of about 3. Ie, for each joule of energy supplied (in the electricity required to power the heat pump), it returns 3 joules of useful energy (in heat) to the house. There are very few active devices that have such outstanding COPs.
Of course, it certainly helps to have the home well-insulated. Indeed, the best return on investment comes from insulating the house before all else.
Air heat pumps from Hallowell and Fujitsu are shifting the cost-benefit balance fairly sharply from ground to air. I believe they're achieving high COP's down to -20F.
We've discussed this before. Hallowell doesn't show (at least that I can find) their COP as a function of temperature. My guess is that physics works against your optimistic guess on this. But we are both just guessing.
"My guess is that physics works against your optimistic guess on this."
Well, Carnot efficiency is measured from absolute zero (-273C), so all of these devices are pretty far from their theoretical limit. Assuming outlet temp of 95F and ground temp of 56F, a ground source heat pump should get a COP of 14, and an air source should get 8.8 at freezing and 5.8 at 0F! AFAIK it's a question of engineering - getting the right materials with the right phase-changes, minimizing heat losses, etc.
"we are both just guessing"
Yes, I'd like more info. This article ( http://bangornews.com/news/t/viewpoints.aspx?articleid=165927&zoneid=35 ) says "average efficiencies of 250 percent, extracting heat efficiently down to -20 degrees F and colder". http://en.wikipedia.org/wiki/Heat_pump has some sources, including Carrier ( http://www.residential.carrier.com/products/acheatpumps/heatpumps/infinity.shtml footnote 9), but not the specific info we'd like. If I have time I'll call Carrier...
Just want to share with others. We are working on using ground sink for air-conditioning in Perlis, Malaysia. And we just started to run it a few days ago. The problem is the compressor of GSHP is not well-function. We are using the same compressor as the conventional ASHP air-conditioner. As what I know, the normal compressor will stop for a while when the temperature in the room is colder and will automatically start back, right? But when the ground sink compressor stop, it will not start again. It will just stop until we off and on it manually. Did the compressor has already getting overload? maybe by the ground loop? Is the length of the ground loop/condenser will affect the compressor performance? For your information, the weather here is hot humid climate, sometimes it rain, sometimes not.