heat pump

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How Does a Heat Pump Get Heat From Cold Air?

The physics of heat pumps isn’t really that difficult to understand

Posted on Dec 6 2017 by Allison A. Bailes III, PhD
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Cold weather is coming back to Atlanta this week, so let’s talk about heat. An increasingly popular way to heat buildings these days is with heat pumps, even in cold climates. But how do they work?


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Image Credits:

  1. Energy Vanguard

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Are Ductless Minisplits Overpriced?

An installer’s estimate has one homeowner wondering whether he should install the unit himself

Posted on Apr 3 2017 by Scott Gibson

Ductless minisplit heat pumps have received a tremendous amount of attention in the last several years, and Peter L. would like to include one in his own house. There's only one problem: an estimate that seems far higher than it should.

"I was quoted $4,800 to purchase and install a Mitsubishi Mr. Slim 1-ton unit (MSZFE12NA)," Peter writes at GBA's Q&A forum. "That seems very high. Especially since it's a new build and the 3-inch hole is already in the wall."


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  1. Scott Gibson

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Manual J Doesn’t Tell You Equipment Capacity

The amount of heating and cooling your house needs isn’t the only factor in determining the size of your heating and cooling equipment

Posted on Mar 8 2017 by Allison A. Bailes III, PhD
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Here's a little conundrum for you. To get the right amount of heating and cooling to each room in your home, you need a load calculation. Rules of thumb don't work. But if you do a load calculation, the result isn't the size of air conditioner, heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump., furnace, or boiler you need. It's only the first step to sizing your system.

Do you know why? Let's take a look.


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Image Credits:

  1. Energy Vanguard

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Is a Ground-Source Heat Pump the Right Choice?

To bring the cost of a system down, this GBA reader suggests placing heat exchange tubing beneath the basement slab

Posted on Oct 24 2016 by Scott Gibson

Ben Rush likes the idea of a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures., despite their reputation for higher cost than other heating and cooling alternatives.

A ground-source heat pump (GSHPs) requires heat-exchange tubing buried in the ground or inserted in a well or pond. The excavation required to bury the lines (or drill an extra well or two) helps to make GSHPs more expensive than air-source units. In addition, the equipment itself tends to be more costly. In all, GSHPs suffer a significant disadvantage when it comes to cost.


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Image Credits:

  1. National Renewable Energy Laboratory

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Should We Promote Heat Pumps to Save Energy?

Replacing electric resistance heat with heat pumps could trim the nation's consumption of electricity by 2% — but in very cold states, gas furnaces still use less energy

Posted on Jun 2 2016 by Steven Nadel

Heat pumps are going through a period of innovation. Ductless heat pumps are more available; cold climate heat pumps have been developed; higher minimum efficiency standards for heat pumps have been established by the U.S. government; and gas-fired heat pumps have been developed.


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Image Credits:

  1. BlueberarsLair / CC BY-ND 2.0 / Flickr

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The Carbon Footprint of Minisplits

Is heating with a minisplit heat pump really ‘greener’ than heating with fossil fuels?

Posted on Mar 29 2016 by Dana Dorsett

It’s often presumed that heating with high-efficiency heat pumps has a lower carbon footprintAmount of carbon dioxide and other greenhouse gases that a person, community, industry, or other entity contributes to the atmosphere through energy use, transportation, and other means. than heating with other equipment (and often it is). But how do you really know?

Do the math!


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BuildingGreen Names Top 10 Products

This year's list includes a variety of products that save energy or water and do less environmental damage than conventional products

Posted on Nov 19 2015 by Scott Gibson

Two kinds of office chairs, a clothes dryer, bicycle storage equipment, and high-performance panelized homes all found a place on BuildingGreen's Top Ten product list for 2016.

The publisher of Environmental Building News and GreenSpec annually recognizes products that it believes "transform the design and construction industry" by reducing greenhouse gas emissions and saving energy and water. This is the 14th year that BuildingGreen has made the awards.

Here's this year's list:


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Image Credits:

  1. All photos: BuildingGreen

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Is a Ground-Source Heat Pump My Best Bet?

With an energy retrofit on the horizon, a homeowner ponders the cost and suitability of a ground-source heat pump

Posted on Apr 27 2015 by Scott Gibson

Cathleen Dalmeida is budgeting for a heating and cooling system as part of an energy retrofit and is wondering whether a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. is part of her future. An obvious question: How much do they cost?

"Is there a general rule of thumb for pricing of a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. and air-to-water heat pump for a medium sized installation?" she asks in a Q&A post at Green Building Advisor.


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Is It OK to Close Air Conditioner Vents in Unused Rooms?

In most cases, the answer is no

Posted on Jul 30 2014 by Allison A. Bailes III, PhD

Your air conditioner, heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump., or furnace probably uses a lot of energy. Heating and cooling makes up about half of the total energy use in a typical house. For air conditioners and heat pumps using electricity generated in fossil-fuel fired power plants, the amount you use at home may be only a third of the total.


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Image Credits:

  1. Energy Vanguard
  2. HVAC Hacks and Other Screwups
  3. Circle Design Technology

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Heat Pumps Get a Leg Up in Vermont

A state agency that promotes energy efficiency will soon be subsidizing the purchase of high-efficiency heat pumps

Posted on Jun 13 2014 by Scott Gibson

More Vermonters will be installing high-efficiency heat pumps in their homes thanks to a bill signed into law by Gov. Peter Shumlin on June 11.

The legislation allows Efficiency Vermont, an agency that collects money from utility ratepayers to fund programs that lower energy consumption, to use some of its $40 million annual budget to subsidize the purchase of high-efficiency heat pumps.


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Image Credits:

  1. Alex Wilson

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