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Base pan heater required for minisplit in Concord, MA?

Lyell Slade | Posted in General Questions on

We are planning on installing 2 mini splits and have already gotten a lot of help from GBA on how to do this. My next question is should we pick units that have a base pan heater or is raising them above ground good enough?


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  1. GBA Editor
    Martin Holladay | | #1

    As far as I know, Mitsubishi and Fujitsu units automatically come with pan heaters. What brand are you installing?

    For more information, see "How To Buy a Ductless Minisplit." In that 2015 article, I wrote:

    "This past winter, many homeowners with minisplit systems had ice buildup in the pans of their outdoor units. ... I asked Vreeland [that is, Cameron Vreeland, Mitsubishi’s manager for residential and light commercial products] whether these icing problems were a sign that Japanese manufacturers hadn’t anticipated New England weather. “No,” Vreeland answered. “It gets cold in many areas of Japan. Mitsubishi tests their equipment in cold temperatures and snowy environments. But here in the eastern U.S., we just we had the coldest winter we’ve ever had, and many locations had more snow than they’ve ever had. I think it has been a learning curve for all the manufacturers.”

    "Until recently, Mitsubishi offered electric-resistance pan heaters as an optional accessory. That’s about to change. “Going forward, the pan heater will be factory-installed for all HyperHeat units,” Vreeland told me.

    "... Fujitsu sells six basic models of outdoor units. Three of them are suitable for mild climates where the temperature rarely goes below -5°F. The other three are similar, but are rated for colder temperatures (down to -15°F). The cold-climate outdoor units have an H at the end of the model number.

    "All of the cold-climate outdoor units have a factory-installed electric-resistance pan heater rated at 150 watts."

  2. Lyell Slade | | #2

    Thank you Martin, It was this article that alerted me to the possible need for a pan heater. The units I'm looking at are Misubishi's. MSZFH09NA does not come with a factory installed pan heater and the MSZFH09NAH does. The contractor is proposing the NA model which does not have the factory installed pan heater and is saying it's not necessary if the unit is raised up.

  3. Brian P | | #3

    We have a Mitsubishi FH12NA in NH (zone 6). This question has been asked before and this was my answer:

    I believe that the function of the base pan heater is protection against ice buildup during defrost mode, especially during low temp and high humidity conditions (which happens in the Northeast), it's not about snow accumulation or level above the ground.

    The installer who put in our FH12NA said the pan heater is required in climates like NH for the warranty to be honored. He is a Mitsubishi Diamond dealer/installer and checked with a Mitsubishi rep, so I believe this info is accurate.

    Based on what I've seen during past winters...quite a bit of water does drain out during defrost mode in high humidity winter weather. Without a pan heater, the ice buildup could be bad.

    You should at least urge your installer to check with a Mitsubishi rep about the need and/or requirement of the base pan heater in your climate, especially related to warranty.

  4. Lyell Slade | | #4

    Thank you Brian P, that is great advice, and I will check with the installer. He is a Diamond Elite installer but was saying that the NAH models weren't eligible for our rebate program (MassCEC). It turns out that the FH09NAH is eligible and the FH15NAH (our other proposed unit) is not, for some reason. We might be willing to forego the rebate if it's really important to have the pan heater.

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