Gas Heat Pumps: Pros and Cons

By HomeAdvisor

Updated March 10, 2017

Gas Heat Pumps

Sometimes referred to as absorption pumps, gas heat pumps work similarly to any other air-source heat pump, except instead of using electricity to fuel their operation they rely on natural gas like furnaces. This alternative form of power comes with many advantages and disadvantages compared to standard products, so as you shop around for the right type of unit there are a few things you’ll want to keep in mind about each model.

What is a Gas Heat Pump?

First, it’s important to understand how an air-source pump works. It is often compared to a refrigerator, where a series of coils and heat pump compressors move warm air to and from the house. For instance, even during the winter, there is still a small amount of warm air outside that can then be captured and forced into the house. During the summer, the “heat pump” can also cool the house, forcing out warm air and pulling in the cold stuff. But often they’re set up like an air conditioner, run by electricity and refrigerants such as Freon. Or they’re available in a geo-thermal system which pulls heat back and forth from the earth.

Gas heat pumps, on the other hand, have an engine operated by natural gas and utilize natural refrigerants, such as ammonia and water. All three do the same type of work, but the methods by which they’re run have significant differences.

What is the Gas Advantage?

Oddly enough, though it uses a non-renewable fossil fuel, a gas heat pump also comes with distinct environmental benefits. First off, it doesn’t use ozone-depleting refrigerants like electric units. And unlike gas or coal furnaces, they don’t have as many harmful emissions. Plus, though electricity may seem cheaper and more eco-friendly, there has been a large rise in electrical consumption in the country, creating dangerous waste, urban blackouts, and occasional power surges.

In fact, many utility companies are feeling the strain from people’s dependence, and overuse, of electrical products. In contrast, gas-generated power can often burn clean and in smaller amounts, especially when it comes to the efficiency associated with heat pumps.

What are the Disadvantages?

Their largest disadvantage is expense since natural gas isn’t cheap. However, overall economics are always relative. For instance, all heat pumps are more efficient and cost-effective compared to gas furnaces and electric air conditioners. And though they may cost a bit more to run than electric air-source systems, gas powered units are less wasteful in terms of operation.

Since all heat pumps rely on outdoor conditions to function, power and dependability are two of the biggest complaints against them. But gas-operated systems often put out more energy than is put into them, making them more trustworthy all year round. Plus, though geo-thermal units are the most efficient and effective over time, their initial installation is expensive and requires quite an investment upfront.

What to Keep in Mind?

All three types of air-source systems are cheaper to install and operate than furnaces or traditional air-conditioners. However, they all also depend on the outdoor environment, which is why they are better suited for warmer, milder climates. As mentioned before, even in the winter there is still warm air that can be moved into the house.

But as the temperatures drop, that ratio quickly shifts and the amount of usable warm air decreases, making your pump work extra hard. And since the entire point of these products is to increase efficiency and save on your energy bills it’s not a good idea to install one in extremely hot or cold areas.

Also, make sure you get it professionally installed. These qualified contractors can help you select the appropriate model with the proper efficiency rating, and they’ll know the best place to put the unit so it isn’t vulnerable to icing, high winds, or other exterior impediments.

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  1. Beth Self, January 18:

    My daughter and her husband have a gas powered heat pump and she doesn’t know if it is supposed to have a filter to clean or replace. She wasn’t there when it was installed and also the thermostat is located in a room that was added on without proper insulation. This is a house built back in the early 1900’s (190-something)-2 story here in Virginia. The cost of natural gas is high and it’s not keeping the home above 60 even though it’s set for 70 degrees. They had the heat pump installed about 2 years ago. The company won’t help with even answering our questions. Thank you.

  2. Ratib, July 4:

    This web site info has a quite few errors but in response to Beth, all ducted systems should have a filter in the airstream. If the unit was sized properly and in good working order it should easily keep the house at or above 70. If the thermostat is located in a room without proper insulation, the unit should overheat the house not underheat. Did it work before? Two years is a long time to live like that, it should have been covered under warranty in the first year. What type of gas-powered system is it?

  3. Tom Seaver, November 25:

    The price of natural gas is way cheaper than electricity. We have saved $136 in 2 months so far

  4. Sterilecuckoo58, January 3:

    Briefly. heat pumps move heat, not the actual air. In winter, the cold air still contains heat energy, but it takes more power to extract the colder that source air is.

    In summer the same equipment is used to move the heat from inside the building to outside.

    Most heat pumps use a refrigerant and utilize phase change to move heat at the same temperature (as is the case for refrigerators, the air-conditioning mode of a heat pump).

    The primary benefit of heat pump systems is the ability to produce more heat in a desired space then the energy consumed to operate the pump. This is referred to a Coefficient of Performance (COP). Electric resistance heat has a COP of 1 while a heat pumps has a COP of 1.4 (low temperature say 17ºF) to 5 (at say 50ºF) depending on the temperature of the source air.

    Depending on where you live the choice of gas vs electricity based on cost is driven by prevailing electric and gas costs for residential use. If the basis is CO₂eq emissions, it is driven by the power producing plant CO₂eq emissions rate per kWh of power as compared to the emissions for a fossil fuel fired pice of heating equipment. In the northeast US, electricity production is about 50% efficient. A gas fired boiler is likely to be about 85%. An electric heat pump operating a COP of 3 has lower emissions because the product of the Power plant and heating equipment efficiencies is 1.5 or 150% [ 50% x 300% = 150%] while the gas boiler is 85%. Even the most efficient gas appliance is limited to 100%.

    But I did not come here to wax eloquent. What I want to understand is the COP of the gas powered heat pump and comprehend the options for such systems. I am trying to avoid a large gas powered generator (about 12% efficient) to run the electric heat pumps on the coldest night (COP 1.4) or electric resistance backup at COP =1.

    I had noted that the air source could include the exhaust from the combustion of gas, increasing the ASHP COP.

  5. Pump Hot water KSB, April 3:

    how to properly care for the gas pump model as above, do you need routine maintenance?

  6. big bank, December 20:

    use air as a working gas in heatpump – what efficiency can i expect?

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