Heat Pump Investment

Heat Transfer and Air-Source Heat Pumps

Recently I have had clients purchase houses with heat pumps installed and it was a main component in the decision to choose the given property.  I have also had clients purchase houses with the intention of investing in this technology.  Interesting.

There are many different kinds of heat pumps, but they all operate on the same basic principle of heat transfer. Heat transfer means that rather than burning fuel to create heat, a device moves heat from one place to another. Heat naturally flows downhill, which means that it tends to move from a location with a high temperature to a location with a lower temperature. A heat pump uses a small amount of energy to switch that process into reverse, pulling heat out of a relatively low-temperature area, and pumping it into a higher temperature area. In a heat pump, this heat is transferred from a heat source (e.g. the ground or air) into a heat sink (e.g. your home).

One of the most common types of heat pumps is the air-source heat pump, which takes heat from the air outside your home and pumps it inside through refrigerant-filled coils. Inside this basic heat pump, you'll find two fans, refrigerator coils, a reversing valve and a compressor.

Here's how this heat pump works:

This system is more commonly known as an air-air heat pump, because it takes heat from outdoor air and transfers it to indoor air ducts. With the proper modification, air-source systems can also work with other types of indoor heating systems.

The reversing valve is a very versatile part of a heat pump. It reverses the flow of the refrigerant, so that the system begins to operate in the opposite direction. Instead of pumping heat inside your home, the heat pump releases it, just like an air conditioner. The refrigerant now absorbs heat on the indoor side of the unit and flows to the outside, where the heat is released and the refrigerant cools and flows back indoors to pick up more heat.

 

Geothermal Heat Pump: How It Works

 

An electrically powered, geothermal heating and cooling system transfers heat between your house and the earth using fluid circulated through long loops of underground pipe.

 

Heat Pump Parts

As with ordinary heat pumps, the refrigerant in a geothermal heat pump runs in a loop through a compressor, condenser, expansion valve, and evaporator, collecting heat at one end and giving it up at the other. The direction of refrigerant flow, which is controlled by the reversing valve, determines whether heat is moving into the house in winter (shown) or being pulled out of it in summer. With the addition of a desuperheater, residual warmth from the system can also supplement a conventional water heater, further reducing energy bills

How It Works

Given all the attention being paid to solar power these days, you might be surprised to learn that one of the most promising solutions to high energy costs isn't up in the sky but buried deep under your lawn. Superefficient geothermal heat pumps provide clean, quiet heating and cooling while cutting utility bills by up to 70 percent. "With this technology, everybody could be sitting on top of their lifetime energy supply," says TOH plumbing and heating expert Richard Trethewey.

In principle, a geothermal heat pump functions like a conventional heat pump, by using high-pressure refrigerant to capture and move heat between indoors and out. The difference is that conventional systems gather their heat—and get rid of it—through the outside air. Geothermal systems, in contrast, transfer heat through long loops of liquid-filled pipe buried in the ground.

As our cave-dwelling ancestors discovered long ago, if you go far enough underground, the earth's temperature stays at a constant 50 degrees or so, no matter how hot or cold it gets outside. So while a conventional "air-source" heat pump struggles to scavenge heat from freezing winter air or to dump it into the summer swelter, its "ground-source" counterpart has the comparatively easy job of extracting and disbursing heat through the 50-degree liquid circulating in its ground loop. That's why it takes only one kilowatt-hour of electricity for a geothermal heat pump to produce nearly 12,000 Btu of cooling or heating. (To produce the same number of Btus, a standard heat pump on a 95-degree day consumes 2.2 kilowatt-hours.) Geothermal systems are twice as efficient as the top-rated air conditioners and almost 50 percent more efficient than the best gas furnaces, all year round.

Another advantage is that there's no need for a noisy outdoor fan to move air through the compressor coils. Geothermal units simply pump liquid, so they can be parked indoors, safe from the elements. Most come with 10-year warranties, but they can last much longer. In the 29 years since Jim Partin, one of the technology's earliest adopters, installed one in his Stillwater, Oklahoma, house, he's replaced only two contact switches.

Despite these benefits, only 47,000 geothermal units were installed last year in the U.S. That's just a tiny blip compared with the approximately one million conventional heat pumps sold during the same period, even though ground-source heat pumps cost about the same to buy. Here's the rub: You have to bury a lot of pipe—about 1,500 to 1,800 feet for a typical 2,000-square-foot home. (The actual length should be calculated by an expert, based on the optimal heating and cooling loads for the house.) A setup that size could cost as much as $20,000 to install, depending on soil conditions and how much digging and drilling is involved. A house on a big lot, for instance, might be able to use pipes laid horizontally in long, 4-foot-deep trenches. Houses on small lots or rocky ledges could require three or four holes drilled about 300 feet straight down, a much more costly process.

The current federal incentive is limited to the standard $300 tax credit for Energy Star HVAC installations. (Canadians retrofitting an existing home with geothermal qualify for a $3,500 federal grant.)

The following link gives a short concise explanation of heat pump performance:

http://www.youtube.com/watch?v=8Bo8exCdsR8&feature=related

 

 

Comments

[airheat pumps]

Great post. I've been thinking about writing something along these lines myself, but you've done a splendid job on the issues of heat pumps. Thanks.

[plumbing]

Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.

[AC Repair]

Tapping into geothermal resourses can save homeowners quite a bit of money and I can understand how a pre-installed heat pump could make the purchase of a house quite attractive.

[Concrete Core Drill]

you've done a splendid job on the issues of heat pumps..Thank you for the post..

[heating and cooling Kansas City]

I am also thinking about buying a heat pump. Its a great alternative for heating. By using heat pump i can also save the fuel cost.

[heat pump costs]

Impressive post. Heat pumps performs well and it saves energy and the fuel cost. I am looking forward to buy this. Thanks for the share.

[Louisville air heat pumps]

Heat pumps provide cooling and heating both in one shopping. You can use it in summer and winter. Also it is much energy efficient rather than any air conditioners.

[Francesco Sortino]

HEAT PUMPS - HEATING AND COOLING BUILDINGS
www.geotermiaitalia.it/catalogo/prodotti.html

Geothermal heat pumps;
Air-water heat pumps;
Exhaust air heat pumps.

They are energy efficient complete systems for heating and cooling which is both economic and environmentally sustainable .
This technology is available both for residential single / multi-family and industrial and commercial buildings.

The geothermal heat pump uses as a heat source the subsoil or ground water and allows a cost savings for the heating up to 80%.
You do not need to reside in a thermal area to enjoy the benefits of underground heat: from 10 m depth the soil temperature remains almost constant throughout the year, and around 100 meters the temperatures are around the 10-12 °C constituting a heat source for the optimum operation of the heat pump.

The air-water heat pump uses as a source of heat the outside air and allows a cost savings for the heating up to 50-60%.
It can produce hot water for heating or sanitary uses up to temperatures of 65 °C with only the compressor and work up to temperatures of -25 °C!

The exhaust air heat pump uses as a heat source stale air present in the house, allows a cost savings for the heating up to 50%.