How to Compare Air Conditioners & Heat Pumps

An air conditioner is actually a specific type of heat pump. Both types of equipment transfer heat between indoors and outdoors by circulating a heat-storing fluid into and out of the building. The difference is that an air conditioner exclusively cools the building, while a heat pump can either heat or cool it by moving heat indoors or outdoors.

Instructions

Steps

1. Decide if you need a new heat source. If you are looking solely for a way to cool your house or building, an air conditioner is the logical choice. However, you should still consider heat pumps for their possible energy savings over other heating methods in many locations. Air-source heat pumps work very well in mildly cold weather, and ground-source heat pumps can work well in below-freezing temperatures. Hybrid systems also exist that utilize air-source heat pumps for chilly temperatures and furnaces for frigid temperatures, increasing overall efficiency.

2. Compare the up-front costs. You can expect a heat pump to cost slightly more than an air conditioner due to its versatility. Contractors may charge slightly more to install an air-source heat pump than an air-conditioner, but significantly more for a ground-source heat pump. Installation of a ground-source heat pump requires a technician to install an expanse of coils several feet underground.

3. Compare their efficiencies. The efficiency of cooling for both a heat pump and an air conditioner is represented by a SEER rating, which stands for "seasonal energy efficiency ratio". The SEER rating will provide you with the expected cooling output divided by electricity consumed in a typical cooling season. This means that heat pumps with higher SEER ratings are more efficient. Heat pumps (but not air conditioners) will also have an HSPF rating, or Heat System Performance Factor. Similarly to the SEER rating, the HSPF gives the expected heat output divided by energy input for a typical heating season. You must compare the HSPF rating to the furnace's or existing heating source's efficiency to determine which will save more energy.

4. Calculate paybacks. When you have two or more potential models selected, you can compare their values by calculating how much each will cost in utility bills for heating and cooling seasons. A higher initial cost often pays for itself over the years; ground-source heat pumps, for example, can be 1.5 to 2 times more efficient than air-source heat pumps or air-conditioners. You can use your utility meters and rates to estimate current consumption and cost, and then apply arithmetic based on SEER and HSPF ratings to estimate future figures. If you are deciding on a system for a new construction project, you will need an HVAC specialist or energy modeler to perform load calculations.

Tips & Warnings

• While cost and energy efficiency are important, also consider the quality and reliability of the brand. A qualified contractor should install the equipment, because poor installation can ruin any energy savings.

References

• Southface Energy Institute: Choosing Heating and Cooling Equipment