Can you work with the proprietary controller for a Fujitsu Heat Pump?

My wife and I are thinking about replacing our 18 year-old gas furnace with a super-efficient Fujitsu mini-split heat pump. Our HVAC tech tells us Fujitsu has high-frequency proprietary controllers to ensure high performance, which are incompatible with Nest or similar low-voltage smart thermostats. The best I can figure out is combining a Intesis wifi controller with IFTTT, but I don't see either of those listed on your device dropdown.

Do you have any ideas for making this work? Is it possible?
If your interface can't work with Fujitsu, can you recommend comparable brands for us to look into (Similar efficiency, affordability, esthetics, etc)?

I'm very excited about this project because it combines the major themes for long-term climate stabilization in California: renewable electricity, swapping fossil fuels for clean electricity, efficiency, and demand response. I researched these topics while I was a scholar at UC Berkeley and an Energy Commissioner for the City of Berkeley, but this is the first chance I have to put all of these pieces together in my own home, so I am very excited. It feels like the future is almost here!

Thanks in advance for your assistance.
Dr. Josiah Johnston


  • John KJohn K Lake Forest - Hikers and Bikers TeamMember Posts: 585

    @josiah-johnston said:
    Our HVAC tech tells us Fujitsu has high-frequency proprietary controllers to ensure high performance, which are incompatible with Nest or similar low-voltage smart thermostats.

    Do you have any ideas for making this work? Is it possible?

    If the Fujitsu unit plugs into a standard wall outlet, it should be as simple as putting a TP-Link smartplug into the outlet. If the unit is normally hardwired, you might ask whether the installer can put a plug on it instead.

  • josiah-johnstonjosiah-johnston Member Posts: 5

    Hi John.

    That isn't really an option for a house-wide heat pump that runs on a dedicated 240 Volt circuit. Also, anything that runs a refrigerant cycle will have a shorter lifetime if you regularly shut off its power during the middle of its cycle. Refrigerators, window ACs, heat pumps for space heating or water heating all fall into this category. Effective DR for those appliances need a smarter plug that can sense when it is safe to turn those appliances off. If it's an old appliance that you don't care about breaking, maybe not a big deal though..

  • josiah-johnstonjosiah-johnston Member Posts: 5

    Hi UkiwiS.

    I saw that post too, but every proposed solution included a follow-up post explaining why it was problematic or wouldn't work. For example:

    After exploring it with a rep, CoolRemote is expensive and you have to wire the whole house. Not an easy solution as their site claims.

    That made me want to see if there was another approach that might have better support with OhmConnect.

    For the record, the best description I found for the CoolRemote system for minisplits is here:
    I've contacted our HVAC company to see how that would impact their estimate for our new system. Maybe I'll get lucky and the costs will be comparable to other controllers. If the naysayer from the nest thread was talking about a retrofit vs new install, that could explain why it seemed impractical.


  • josiah-johnstonjosiah-johnston Member Posts: 5

    Just talked to my HVAC company rep. All the wifi-enabled controllers he were familiar with just acted like a replacement for the IR remotes that come with Fujitsu heads, but many third party controllers weren't fully compatible and could make the heat pump much less efficient. Sometimes by bypassing the inverter and forcing the system to run either at 0 or 100% output (and nothing in between). He was confused by the CoolPlug/CoolAutomation option because it is supposed to wire into heads directly instead of communicating via IR, and as far as he knew, the standard Fujitsu heads didn't even accept a wired connection. With the CoolPlug option, it's also unclear if I'd need a separate Nest for each room, or one for the whole house. I sent some help requests to that company to try to understand that better.

    Our HVAC guy uses a Honeywell D6 thermostat to control one of the fujitsu minisplit heads in his own home, which plugs into a wall socket and is positioned to have an IR line of site to the mini-split head. It's biggest downside is sabotaging the oscillation feature which can increase comfort on hot days without having to set the AC quite as low. Well, the other downside would be having to buy a $160 controller for each room.

    I also sent a message to the OhmConnect support staff, asking if they knew of any standard solutions for automating their DR control for high-efficiency mini-split heat pumps, and what their thoughts were on the Honeywell D6 option. I'll repost their response here unless they do it directly.

  • josiah-johnstonjosiah-johnston Member Posts: 5
    edited January 2019

    I just heard back from OhmConnect staff. They said they had no experience interfacing with high-efficiency heat pumps. That's unfortunate given the importance of high-effiency heat pumps in California's emission reduction plans.

    I'm still pestering them to say whether or not they can talk to the Honeywell D6 controllers.

    Jan 11 Update:
    I heard back from OhmConnect staff again, and now I'm getting the impression that high-efficiency heat pumps are cutting-edge technology for OhmConnect and they're trying to get up to speed.
    They said they can't talk to Honeywell D6 controllers, but do have experimental IFTTT integration, and some folks have written IFTTT applets to control honeywell total connect thermostats.
    The caveats of this beta IFTTT integration are:

    • could be buggy
    • no guarantees of support
    • no bonus points for IFTTT-controlled devices (yet)
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