Heat Pump & Generator Pairing

Challenge: Keeping the HVAC on during power outages caused by severe weather.

Solution: A residential generator and a Mitsubishi Electric all-climate heat pump can keep the home powered and the HVAC running.

Result: A Mitsubishi Electric all-climate heat pump system paired with a generator can keep homes comfortable when the power goes out.

Few Texas residents will ever forget February 2021.

A deep freeze impacted parts of the continental United States, with Texas experiencing the coldest winter storm since 1989. Lasting for almost nine days, the Great Texas Freeze caused water pipes to burst in homes and commercial buildings, with power outages causing damage and leaving approximately 10 million Texans in the dark and without warmth.

David Trumbly, area sales manager at Mitsubishi Electric Trane HVAC US (METUS), was fortunate enough to keep the power in his northern Houston home during the historic event. However, with extreme temperature swings, severe weather and rolling brownouts occuring more frequently in the Lone Star State, he decided it was only a matter of time until his home would fall victim to a future power outage. So, after researching everything from small, portable generators to whole-home/home standby systems, Trumbly purchased a mid-sized portable generator.

"A whole-home generator cost more than I was willing to spend, and a smaller one wasn't going to power what I wanted. I found a mid-sized generator that works perfectly with my Mitsubishi Electric all-climate heat pump solution and the other electronics I wanted to run," he said.

If David had a conventional HVAC system, systems that are usually fully on or fully off, he would have needed a large, whole-home generator to power it. Heat pump systems, on the other hand, are more customizable, and homeowners only need to power the parts of the systems that they need. Heat pump systems are a perfect fit for smaller, mid-sized residential generators.

The purchase paid off. When Hurricane Beryl made landfall in Texas in July of 2024, Trumbly's home lost power for about 18 hours. However, the residential generator powered his 3.5-ton ducted, all-climate heat pump systems and six other circuits to keep the refrigerator, a computer, and the lights on.

Being Prepared For Future Power Outages

Texas is the only state with its own power grid. Its grid relies on natural gas and wind turbines to generate most of the state's electricity. However, the infrastructure isn't winterized against freezing temperatures, which led to the state's 2021 winter blackout.

"We're also starting to see more infrastructure problems with the amount of power that's available during peak times, so even if you don't lose power, rolling brownouts can occur," Trumbly said. "They are very real and on Texans' minds."

According to Climate Central, Texas endured 210 power outages from 2000 to 2023 - more than any other state. It is followed by Michigan (157), California (145), North Carolina (111), and Ohio (88).

Given these trends, Trumbly believes his generator purchase will get plenty of use in the future.

Getting Familiar With The Simplicity Of A Generator

Because he thinks it will be used for imminent power outages, Trumbly stores the portable generator in his garage near the transfer panel. When it's needed, he wheels the generator to the side of his house and plugs it in to start it.

Next to the home's electric panel is a transfer switch, directly attached to the all-climate heat pump system's circuit. When the transfer switch and generator are plugged in and turned on, the generator powers the all-climate heat pump, electrical appliances, and lights, among other devices.

The switch on the transfer panel shows whether power comes from the utility provider or from the generator. The generator system has built-in safety features that prevent it from back-feeding to the power lines, which can keep utility workers safe from shock. Homeowners are also kept safe by not having to use too many electrical cords.

When Trumbly plugs in the generator and turns on the switch, power disconnects from the main electrical panel and comes from the generator. Newer generators like his are equipped with a carbon monoxide sensor that automatically shuts off the generator when carbon monoxide builds up. Similarly, newer generators automatically shut down when there's too sudden of a power draw.

He also pointed out that all-climate heat pump systems are much easier to start and run with a generator than fossil fuel-dependent conventional HVAC systems. All-climate heat pumps require less power than conventional systems when paired with a generator.

Training Others To Recommend Generator-Heat Pump Combos

Trumbly freely shares his knowledge and experience regarding his powerful heat pump-generator combo by providing 30-minute training sessions for HVAC contractors and distributors of Mitsubishi Electric heat pump solutons. A high-level overview, Generator Application of Inverter Systems, is available here.

The generator-specific traning Trumbly provides includes:

Calculating the power/wattage (volts x amps = watts) needed to start and run an all-climate heat pump system, appliances, and other devices, along with how to access this information.
Using wattage requirements to choose the right residential generator to serve a homeowner's needs during power outages.
Understanding the pros and cons of a small, inverter-powered generator; a portable, mid-sized generator; and a whole-house generator, as well as their price ranges.
Determining whether a generator provides 'clean power', a term that in this case means the ability to provide a steady stream of power rather than spikes that can burn out a circuit board.

The virtual workshop arms contractors and distributors of Mitsubishi Electric systems with the knowledge to offer customers cost-effective solutions to help keep their power running during future outages. Those interested in the virtual workshop should contact their METUS representative.

"I often ask customers, 'What did you experience during the last power outage?' This usually begins with a conversation in which the homeowner shares the story of difficulty their family had to endure with no heating, air conditioning, or any power at all," Trumbly said.

Offering Sound Advice To Homeowners

Trumbly believes HVAC contractors should be consultative and prepared to offer all-climate heat pump-generator solutions before the next power outage event occurs.

Contractors should also let homeowners know that while generators can help keep conventional systems running during a power outage, they take more wattage to do so than when generators are powering all-climate heat pumps. Powering an all-climate heat pump with a generator could be a much better fit for homeowners.

Extreme weather events are not going away. Homeowners want to be prepared to go about their daily lives even when power outages occur. When contractors recommend pairing a generator with a Mitsubishi Electric all-climate heat pump, they can turn a negative experience such as living without lighting, heating, and cooling into a positive one in which life goes on comfortably.