What Factors Affect the Efficiency of Your Heat Pump?

What makes some heat pumps more efficient than others? There are several factors that can help give you the highest efficient heat pump system. Look for models that offer these features in order to reduce energy use and costs as much as possible. As a bonus, the same features that make heat pumps more efficient also contribute to more comfortable heating and cooling. Here are the key factors affecting heat pump efficiency.

Compressor Efficiency

The main reason for one heat pump being a 22 SEER model and another being a 14 SEER model is the design of the compressor. The more efficiently it uses electricity to circulate refrigerant, the less energy it will use. The more efficient a compressor and supporting parts are, the more the unit will cost, due to the complexity of the equipment. This is the reason not all heat pumps use the most efficient compressors available.

Compressor Type

There are 3 types of compressors being used today. A single-stage compressor is the least efficient. When the heat pump is on, a single-stage compressor is running at 100% capacity. This leads to slight overheating and overcooling in every cycle. It’s like a vehicle travelling at full speed and then having to stop quickly – it will overshoot the mark. The effect of running at full capacity all the time is wasted energy.

Two-stage compressors run at low capacity, which is about 65%, most of the time. Therefore, they are going “slower” when the cycle ends, making it much easier for them to stop. The most efficient compressor types are modulating compressors found on models like the Maytag PSH4BI iQ Drive and the Carrier Infinity 25VNAO Greenspeed heat pumps. They run as low as 40% capacity which makes it much easier to control the amount of heating and cooling produced during the cycle.

Currently, the most efficient single-stage compressors offer 16 SEER cooling. The most efficient 2-stage models are 19 SEER. Rotary heat pumps offer SEER ratings as high as 22 in heat pumps or over 24 in air conditioners.

Air Handler Type

The final key factor affecting heat pump efficiency is the type of air handler the system uses. A variable-speed air handler can increase SEER ratings by up to 1.5 points. It’s the same principle of a modulating compressor versus a single-stage compressor. A variable-speed blower will match the capacity of the heat pump to produce longer, lower-capacity cycles that make better use of the heated or cooled air that is produced.

In addition, variable-speed blowers that produce longer cycles do a better job removing humidity in cooling mode. Humidity is a major factor in how comfortable you feel. When it’s less humid, you feel just as comfortable at a higher temperature. With a variable-speed air handler, you can achieve the same indoor comfort by setting your thermostat to a temperature 2-3 degrees higher than you would with air handler that does not have a variable-speed blower.

As noted, the more efficient a heat pump system is, the more it will cost. The upside is greater indoor comfort and lower energy bills. Depending on your climate and the model you choose, a higher-efficiency model will pay you back through lower energy bills in 1-7 years.