www.hvactechgroup.com - forums

Hey folks, I'm trying to figure out how to get a smart thermostat hooked up in my home. I have a variable speed fan which I see new Nest and EcoBee thermostats do support. The hard part is my thermostat only has two wires connected, although there's multiple wires run to make future expansion easier (thankfully). The furnace itself also has all the different connections but only two are in use for the current thermostat. I know I'm doing the best job explaining so I've attached a bunch of pictures of what my setup is. It's an all electric central air heatpump. Looks like two mini splits stacked on top of each other, I've never actually seen on of these before.

So my questions are:
1 - is it possible to get a smart thermostat to work here and retain the variable fan speed functionality?
2 - with all the wires already run, is it easy enough to diy? I may not know all the technical terms for HVAC stuff but I am comfortable with wiring as long as it's explained to me lol. I will call in a pro if it's too much though, no problem there.

I'm located in Moncton, NB, Canada for what it's worth. We're about to get our one year home warranty done so I'll be swapping it out after that (if it's possible).

Thanks for any help/guidance!

That system seems to support a non-communicating thermostat so the Ecobee should work.  The Ecobee has a setting that will let the air handler control the fan speeds so there shouldn't be a problem there.

If you had six wires to use for the thermostat and five wires to the outdoor unit you should be able to eliminate the two wires.

I would check the manual to see if there are any dip switch settings required to switch to a non-communicating thermostat.

Otherwise I would just follow the wiring you have marked up on the 2H and 2C, if in fact that is a two stage system.

Thanks for the response, I appreciate the info. Regarding the notes that were marked up, that was from when the original installers tried to install an Ecobee but said they couldn't get it to work. However they also said it was the first time they installed something like this.

I also found the part in the manual about the dis switches and I don't fully understand it. I think I may be better off finding someone local who can actually come in and do the install. The more I'm looking into this, the more I'm not fully understanding and I don't want to cause a very expensive headache lol. And I'd feel bad asking to be walked through step by step.

I installed an Ecobee at my previous home and I think I was riding the high of doing that myself (with all required wiring already existing haha).

Thanks again!

I would help if I could find the manual.  It's hard to find online.

Oh awesome, yeah I'd really appreciate that, thanks so much!

I've attached the pages referring to the wiring and dip switches. Let me know if there's any other info you need!

If you read the NOTE in Pic 3, I think it suggests using a combination of Wiring Method B and C because your Ecobee does not have an L terminal.  I'm wondering if you need to jumper the R and L terminals in the indoor unit, then use the Wiring Method C for 2H / 2C.  Otherwise if you only use Wiring Method C you have to run a wire from the indoor unit L to the normally closed side of the AC contactor.  I would be calling their tech support before I did jumper those terminals though.

Also Pic 6 shows that dip switch SW1-1 should be moved to ON for a 24V wire controller.  Did they have that set right?

Okay, that's making a lot more sense to me, I didn't really understand what that note meant but you've clarified that nicely.

I'm not sure if they had the dip switch set correctly as it was all done during the construction of the home and I wasn't on site when they did this stuff to ask anything. I just got a call from the home warranty people though and one of my issues is that the current thermostat no longer shows the current temperature in the house, only ever shows what the current set value is. I'm going to see if they can replace it with an Ecobee even if for an upgrade charge or something and I can pass along the information you've given me.

Really appreciate the help, hopefully they can get it sorted out for me with what you've provided. If not I'll call the tech support line.

I'll update you with how it goes!