FLEXtime Mitsubishi Electric Intelli Heat Coils

[@edbouhl3100]

California homeowner here. I’m interested in this product because in an extended power outage during cold weather where I’m relying on a PV/battery/generator home microgrid, the energy and power demands of a heat pump are a problem. So keeping my old natural gas furnace on standby (with a propane conversion kit in case the gas supply also fails) is a plus. Unthinkable weather is just something that hasn’t happened in your neighborhood yet.

[@MrWoodward42]

This is a really excellent presentation! I've been trying to figure out how Hybrid Heat (aka. "Dual Fuel") systems work as none of the manufacturers' websites really explain it in detail. (I guess they think the consumer isn't smart enough to understand?) -- I see now that some manufacturers put the coil inside their furnace and then they just couple the heat pump with these furnaces (that have coils pre-installed), whereas Mitsubishi does not sell furnaces (thanks for pointing that out!) But Mitsubishi does manufacture air handlers ("the coil"?) that can be installed on top of a new or existing furnace. Then the air handler controls the furnace and is also connected to a Mitsubishi heat pump. And the thermostat connects back to the air handler. Did I understand this correctly?

[@brianbrowning9124]

Hi. I have one of these installed (PAA-a24with PUZ-a24 and par-40maau wired controller) the system works great although I do not have “auto” mode available. My understanding is the PUZ models are auto switching. Any idea why this wouldn’t be available in auto mode?

[@sgtorrice]

Hey Brian, Thanks for the question, we just recorded a podcast addressing this! As for the PUZ having "Auto" mode, you might need to go activate "Auto" mode. Best thing to do here is reach out to our tech line [phone] and ask or reach out to our [e-mail] email and one of our guys will help you with that. Thanks again, good luck with everything!

[@RichZamora-n3c]

Awesome info fellas. Can we do something to show how to change the changeover set point. Meaning it is set at factory to switch to the furnace at 32 degrees. How do we set it to switch at say 40 degrees. Or give the homeowner the ability to control the changeover.

[@brianbrowning9124]

There are various set points that are accomplished by varying function modes 8 and 10. It is detailed in the installation manual.

[@sgtorrice]

Thanks for the kind words! We actually just recorded a podcast to go through this for folks! As for the settings, Brian nailed it in his comment. Page 89 of the install manual. If you want to have a setpoint of 40 degrees, you will need to have a 3rd party thermostat with the 445 Thermostat interface (www.sgtorrice.com/1100147/product/n/mitsubishi-electric-60667) and the remote temperature sensor for outdoor temperature (www.sgtorrice.com/1018812/product/n/mitsubishi-electric-10611). Thanks again for reaching out! Hope this helps!

[@fragdoc6493]

A video explaining how these work with an Ecobee or other smart thermostat would be awesome. For some details, I’m currently in the middle of getting one installed and our Diamond Elite contractor cannot figure it out. I’ve had to direct most of the install by watching your videos, reading the manual, and referencing both the PAC-US445CN-1 manual and the Application Note 3062. Unfortunately, our installer is saying they’ve received no training from Mitsubishi on these intelli-HEAT units and we’re the first install they’ve done. They’ve had technicians out here for days and they still can’t figure it out. Apparently the local distributor is also unfamiliar with the devices. It took nearly a week for the installer to realize that the 445 had a PAA accessory cable and several more days before the dip switches were found. They still can’t get the furnace to respond and ramp correctly. We want the Ecobee to raise the set temperature above 32, which we’re being told is not possible despite being in a more moderate to warm climate. As a consumer, it’s been a real mess. Your messaging seems to imply it is possible. My best guess is that this is accomplished by setting the compressor minimum outdoor temperature threshold and using the nearest weather station as the “outdoor sensor.” As someone who read the full install manual, Mitsubishi really needs to own up to not being more clear on how these third-party thermostats will integrate or at least referencing the 445’s existence in the main manual. From looking on several HVAC forums, multiple customers across the US are having this issue and many are being forced into the MHK2. Kumo is a nightmare for smart home integration.

[@sgtorrice]

@@fragdoc6493 Not a perfect solution, but we did discuss this a bit on a recent podcast: sgtorrice.podbean.com/e/tech-talk-episode-87-mitsubishi-electric-paa-coil-advanced-settings/. We will work with Mitsubishi Electric as well to try to get you a more complete answer. Thanks!

[@fragdoc6493]

@@sgtorrice Thank you. I see you attempted to answer our questions. Your videos have been of immense help in this process. My technician was literally watching your video with me earlier today. We believe we now have the Ecobee thermostats integrated. Three questions: 1) My installer’s assumption is that the Ecobee uses local weather station information that it gets off of the web as its “exterior thermostat” for the minimum compressor temperature for dual fuel. Sound correct? We were actually not opposed to a Mitsubishi PAR-40 thermostat (or MHK2) but our need to set the economic balance point higher precluded that. Big oversight in the programming for Mitsubishi in our opinion. 2) Furnace blower. Our installer chose a variable speed ECM for this project. How does intelli-HEAT handle the logic for this? The installer said that because it only uses Y1/Y2 with a jumped G signal that it effectively puts the blower into low and high mode only. Is there something he’s missing or should the furnace logic board and dip switches somewhat control how it ramps when cooling? We’ve seen from other presentations that the true efficiency of this unit is highly determined by the attached furnace. 3) Could we install a PAR-40 in addition to the PAC-US445 for diagnostic purposes, especially for the installers? The application 3060 document seems to imply that it is possible but our concern is that they’d fight each other for control. 3060 states that TI2 takes precedence. The thought was to install the PAR-40 with the unit for their technicians to pull trouble codes.