Brownstone Boys: Can You Cool and Heat Your Home Exclusively With a Mini Split and Heat Pump?

Editor’s note: Welcome to the 77th installment of Brownstone Boys Reno, a reader renovation diary about renovating a brownstone in Bed Stuy. See the first one here. They also blog at www.thebrownstoneboys.com.

Now that the summer heat is setting in we’ve been regularly using our new mini split system to cool our home. We had some questions about how well the system and configuration would work. We installed only one 18,000 BTU unit for the entire parlor floor. Even though it is fairly open, it’s about 800 square feet. Recommendations call for much more than that one unit. After some pretty hot and muggy days we can definitely say that it passed with flying colors! It gives the parlor floor a department store level of cool in just a couple of minutes. We even find ourselves turning it off if it gets too cold. The smaller 7,000 BTU units we installed in each bedroom are doing just as well. It has us thinking: Could we exclusively use our mini split systems’s heat pump to heat our home as well?

Heating your home might be the last thing you want to think about right now, but if you’re planning a new AC system it might be the time to consider it. Manufacturers of mini split heat pumps have been touting new technology that supposedly makes it possible to use the pumps as an exclusive heating system, but many people still warn against it. In the northeast’s frigid temperatures, they say, a mini split heat pump is really meant to supplement a traditional heating system. So which is it?

How Do Heat Pumps Work?

Let’s start with how heat pumps work. We won’t go too deep into the physics of it (because honestly some of the details are foggy even to us!) but unlike traditional heating systems that burn some sort of fuel source to heat water, steam or air, heat pumps simply (or not so simply??‍♂️) pull heat from the air outside to raise the temperature in your home. Yes, even when it is well below freezing outside. That can be hard for some people to wrap their heads around, but even if it’s 20 degrees Fahrenheit outside, there is still enough heat in the air for the heat pump to operate at 100 percent heating capacity.

Can It Exclusively Heat My Home?

Depending on the brand and features, some mini split heat pumps can continue to operate at 100 percent heating capacity down to -15 degrees Fahrenheit. At some point all of them will provide less heating capacity if it gets cold enough, which unfortunately might be when you need it the most! Early adopters of the new technology are betting on temperatures not sinking that low, and it’s probably a good bet. The coldest monthly average low in New York City is 26 degrees. The lowest recorded temperature since 1869 was in 1934 and it was (coincidentally) -15 degrees Fahrenheit. In the last 10 years, negative temperatures have been reached only once, and it was -1 degree Fahrenheit. So the bottom line is that if you get the right system you should never experience a situation where you have decreased heating capacity. Also, remember that even if we have a once-in-a-century cold spell it doesn’t mean no heat, just less. Potentially the heat pump may operate at 70 percent heating capacity rather than 100 percent. If you’re reading this from northern Saskatchewan, maybe a mini split heat pump is not for you.

Other Considerations

One of the advantages a mini split system has over a ducted central cooling system is its ability to be operated in zones. You don’t need to cool parts of your home you’re not using. Obviously that’s much more efficient than cooling potentially thousands of lonely square feet. For heating, we personally feel this might not work as well if you’re using it exclusively. We prefer to have our entire home cozy and warm. It doesn’t really work to heat some rooms and not others (our home is not that big!). So we would likely have all units running to heat the entire house. We also didn’t install units in the bathrooms (nor would most people) so those rooms would need an alternative heating source (heated floors anyone?).

If you’re interested in going green or having a carbon neutral home, a mini split system can be a piece of the puzzle. If you install solar panels and you are able to produce enough amps to run your home and HVAC system, it can take you a step closer to operating off the grid.

We’ve been stubbornly resistant to considering making the switch to cooling AND heating exclusively with a ductless mini split system and mini split heat pump, but the better the technology gets (it’s pretty much there), the more we learn about it, and the increasingly positive reviews we hear from those who are doing it, slowly but surely we are changing our minds. Maybe we’ll give it a go this winter and report back how well it works.

[Photos by Brownstone Boys unless noted otherwise]

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