The specification you’ll want to look for is the Locked Rotor Amps or LRA for the compressor. Add this value to the rated Full Load Amps or FLA for the condenser and evaporator fans. Then multiply by the minimum voltage to get the minimum generator wattage needed to operate the heat pump safely.

What to Watch For

Energy efficiency policy in some areas has led to utilities pushing for electrification of homes, including their HVAC systems. Many don’t realize that switching from a furnace to a heat pump is not as simple as it sounds. Highly knowledgeable and trained contractors are vital to the success of these utility programs.

If you see an increased demand for heat pumps in your area, maintain a keen focus on performance. Keep in mind the specific nuances and complexities we’ve discussed here. Remember: electrification does present opportunities

Performance Opportunities

Suppose you feel your business could benefit from additional training on some of these topics. In that case, I encourage you to check out the following courses from National Comfort Institute (NCI) to help you enjoy even greater success in helping your customers make the switch:

  • Performance-Based Selling will teach you how to tailor your message to customers and give them confidence that you’ll help them avoid the potential pitfalls of switching to a heat pump. Find more information on the in-person training here ( or the online live version here (
  • Airflow Testing and Diagnostics will help entry-level technicians measure and learn the importance of proper airflow and duct sizing. The in-person class information is here: Online, live class info is here:
  • Refrigerant-Side Performance helps you take refrigerant gauge pressures and temperatures into account when charging the system. It helps you see the total impact, including on the airside. For in-person class information, go to The online live class information is at
  • Duct System Optimization provides you with a close look at proper duct sizing and how to renovate a duct system so it will have the capacity to handle the required airflow for heat pumps. Training information for the online live class is here: For the in-person training, go to
  • Residential System Performance provides a deep dive on field-measured system performance, so you have the knowledge and tools to prove performance in a heat pump retrofit. In-person class info is here: Online Live class info is here:

The electrification movement is coming. It’s not a matter of when. You need to keep abreast of the activities in your local area and stay on top of what your local utilities are doing to incentivize consumers to make the move to all-electric HVAC systems.

Ben Lipscomb, P.E. has more than 16 years of experience in the HVAC industry, including laboratory and field research, Design/Build contracting, and utility energy efficiency program design. He is National Comfort Institute’s director of engineering and utility programs and may be contacted at