Clean Energy Generation member Larry Heiman examines how his new heat pump HVAC system performed in freezing temperatures and snow storms.

Last September, we spoke with Clean Energy Generation member Larry Heiman about his plan to more efficiently heat and cool his home by upgrading to a heat pump HVAC system – and his not-so-planned upgrade to a heat pump water heater after his old gas water heater unexpectedly bit the dust. Together, we learned from Larry why it’s important to create a plan for home energy improvements you want to make to your home because you never know when the opportunity to upgrade will come sooner than you think. 

Larry’s heat pump HVAC system proved its worth during the hot summer months in Atlanta, Georgia, saving him energy and money on his power bill. Now, Larry joins us again to give us the update he alluded to at the end of his Part 2 blog: how has his new heat pump HVAC performed during this past Georgia winter – snow storms, single-digit temperatures, and all?

Note: Larry notes that nothing major on the energy improvement side has been done since our last conversation. Beyond his minor DIY air sealing, he has not addressed any air leakage from his attic or crawlspace. This gives us a controlled space to assess the performance of his new heat pump HVAC system this winter.  

He emphasizes that you should tackle energy-efficient projects such as air sealing first so you can use your existing systems less. Then, you’ll know what you’ll need from a new system. But this may not be the case for everyone. Often, you upgrade to a more efficient appliance when your old one breaks, like in Larry’s case. 

As we learned in your Part 2 blog, you opted for a dual-fuel, variable-speed heat pump HVAC system. How have those features helped heat and cool your home since you installed the system last spring? 

Variable-speed aspect

The summertime went well – even with this being the old, leaky house that it is, the difference in cooling was noticeable. The heat pump HVAC cooled our house to the temperature we always cool it to (about 75 degrees), but used less than half of the energy than before. That’s where the variable-speed aspect comes in big time. With a non-variable-speed HVAC system, there are two stages: on or off. When the thermostat tells the AC that it’s time to come on, it comes on at 100% of its power, blasts cold air for however many minutes it needs to, then the thermostat says it’s cold enough, and the AC shuts off. You’re running full power then nothing, full power then nothing. 

With a variable-speed system, there are more power stages; mine is a five-stage system. Stage one means the AC is running at maybe 25% of its full power, but it’s running continuously at that low level versus running at 100% and shutting on and off, on and off. It’s like driving a car: if you go 60 miles an hour for a few seconds then stop over and over, that’s not an efficient way to drive the car. You’d rather go 20 miles an hour smoothly, right? 

Dual-fuel aspect 

Then wintertime came. We’d opted for a dual-fuel heat pump HVAC, where the heat pump part is your primary heat source, but you keep your gas furnace – or, in our case, upgrade to a newer gas furnace – that serves as the auxiliary heat when outdoor temperatures get too low for the heat pump to continue to heat your home efficiently. 

I thought that we would get almost all of our heating from the heat pump, and the gas furnace would be a “break glass in case of emergency” option, like if temperatures dipped to five or 10 degrees. November was totally like that – I don’t think the gas ever came on. But when it got down to 20 degrees and below in early December, our heat pump started having to work at stage five, or 100% capacity, and it wasn’t enough. Our home would drop to 65 degrees by three o’clock in the morning. The heat pump was losing the battle, so I set up the system to automatically switch to gas when it reaches that point. I don’t want to use gas, and I’m hoping to make some upgrades to my home so the heat pump will win the war more in the future.

My situation is not everyone’s situation. There are issues with my old house that are peculiar and I’m trying to fix that maybe make it more inefficient than the average home. Maybe it’s that we actually could use a larger HVAC system, I’m not sure. But this is the sort of situation you can get into, and it’s why having a dual-fuel system can be nice depending on your home and where you live. 

Larry’s heat pump HVAC system outside his home.

How has your new heat pump HVAC fared during the snow and freezing temperatures Georgia experienced this January? 

I feel comfortable with our choice to install a heat pump HVAC because we have definitely lowered the amount of gas that we use monthly this winter. My heating system tells me how much gas we use in therms, and since the heating season started in November, we’ve used 75 therms, compared to using over 200 therms a month last winter. This is the case despite having to switch to gas occasionally when the heat pump isn’t enough. So yes, I’m using gas more than I thought I would this winter, but it’s not the end of the world and is still way less than before. 

Power Outages

One big reason we chose the dual-fuel heat pump HVAC system – which allowed us to keep our gas furnace – is because we have a backup generator that has always been attached to this house, which is set up to run the gas furnace in case of a power outage. 

And that’s happened to us recently. Around Atlanta at the end of last year, there were severe thunderstorms and a fallen tree brought down the whole power line outside our house. There was a 24-hour period where there was no power, so our generator came on and heated our home with the gas furnace. Then in January, we had about six hours of power outage on a 30-degree day, and again, our gas came on to heat our home. If we had opted for an all-electric system, we would not have had heat. So, resiliency is another bonus there. 

Defrost Cycle

To keep the machine from freezing outside on cold nights – especially if there’s humidity in the air – the heat pump will automatically shut off for a short period of time, maybe ten minutes. At that point, you can program your heat pump to “default to supplemental heat” and run gas heating for the time the defrost cycle is on, or just blow cooler air into your house during that time. We set ours up to default to our gas furnace, since that’s very little gas being used should it have to come on. 

In our last conversation, you said you were eligible for a federal tax credit on your new heat pump water heater, though not your HVAC. Where does that stand as we approach tax season?

I still plan to file for the federal tax credit on our heat pump water heater this year, but nothing feels guaranteed now. I made the decision to opt for a heat pump water heater last year based on the fact that I could get the tax credit by law back then. Hopefully, Congress at least guarantees the tax credit to heat pumps installed, say, before the end of 2025, but you never know.  

What would you say to someone who is considering investing in a heat pump HVAC system but is unsure which option is best for them?

It depends on the energy envelope of your house, whether you have electrical panel capacity for a heat pump – and whether you want to mess around with that – and if your house is hooked up to a gas line if you even have that choice. It’s really not a “one-size-fits-all” kind of thing. Getting a proper energy audit done, where they do all the necessary calculations and tests to tell you what options best fit your situation, helps a lot. 

If my exact house was plopped down in say, Michigan, we would probably go weeks using the gas furnace only – the heat pump wouldn’t be enough to heat the home. But for Georgia’s climate, it works, and it will work hopefully even better as I make more energy efficiency upgrades in the future. 

Check out Larry’s Part 1 and Part 2 blogs for more on his home energy journey.

JOIN THE CLEAN ENERGY GENERATION 

Like Larry, many of us are working to spark change by completing step-by-step energy efficiency upgrades to our homes. Wherever you are in your home energy journey—from taking the DIY route to weatherproof your windows and doors to planning your solar installation years down the line to working with your landlord to install a community EV charger—you’re taking action as part of the Clean Energy Generation, and we’re lucky to have you on board. 

If you haven’t already, we invite you to join the movement and find ways to take action today to secure a safer, healthier tomorrow for all. We’re all in this together! 

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Read Larry’s Part 2 Blog

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