Ecobee thermostat not calling for heat from Mr. Cool Universal Heat Pump

[semipro]

It dropped down to 6F here yesterday and we woke to a cold house. Neither of our Mr. Cool Universal heat pumps was running.
I cranked up our pellet stove in the basement. It hasn't been used in about a year.
I got a fire going in the woodstove in our great room.
Then I hit the internet to try and figure out what was going on with our heat pump system.
My first thought was that the Mr. Cool outside units were not running because of the cold temps outside. I recalled though that one of the reasons I chose those units was because they were rated to heat well even in very cold temps. I checked the specs and confirmed that they are rated down to -15F. I pulled the cover on one of the outside units to check for error codes on the control board display - no codes.
It was then that I realized that the Ecobee thermostats may not be calling for heat from the HP units. I checked their displays and my app to confirm this. I recalled that the Ecobee connects to the WWW by Wi-Fi and that it displays an outdoor weather summary. Realizing that the Ecobees knew that it was 6F outside, I suspected that they thought it was too cold to engage the HP units. I investigated online a bit more and found documentation here on Ecobee "threshold settings".
When I installed the Ecobees I neglected to change the default setting value of +15F for "Compressor Minimum Outdoor Temperature". I reset this value on each thermostat to 0F (the minimum) and both HP units cranked up and started heating the house.

 

[DuaeGuttae]

Good troubleshooting there.

 

[EbS-P]

It dropped down to 6F here yesterday and we woke to a cold house. Neither of our Mr. Cool Universal heat pumps was running.
I cranked up our pellet stove in the basement. It hasn't been used in about a year.
I got a fire going in the woodstove in our great room.
Then I hit the internet to try and figure out what was going on with our heat pump system.
My first thought was that the Mr. Cool outside units were not running because of the cold temps outside. I recalled though that one of the reasons I chose those units was because they were rated to heat well even in very cold temps. I checked the specs and confirmed that they are rated down to -15F. I pulled the cover on one of the outside units to check for error codes on the control board display - no codes.
It was then that I realized that the Ecobee thermostats may not be calling for heat from the HP units. I checked their displays and my app to confirm this. I recalled that the Ecobee connects to the WWW by Wi-Fi and that it displays an outdoor weather summary. Realizing that the Ecobees knew that it was 6F outside, I suspected that they thought it was too cold to engage the HP units. I investigated online a bit more and found documentation here on Ecobee "threshold settings".
When I installed the Ecobees I neglected to change the default setting value of +15F for "Compressor Minimum Outdoor Temperature". I reset this value on each thermostat to 0F (the minimum) and both HP units cranked up and started heating the house.

Zero as a minimum? Is that disabled or when it gets below zero will it happen again? I’m not sold on the smart thermostats yet.

 

[semipro]

Zero as a minimum? Is that disabled or when it gets below zero will it happen again? I’m not sold on the smart thermostats yet.

To be honest I'm not sure but I couldn't seem to disable the function. I was going to suggest that as a software change to Ecobee for future updates.
As of now, I assume if the temps drop below 0F my HPs won't work.

Edit: I just emailed Ecobee support. We'll see if they're responsive.
2nd Edit: I was wrong. You can disable this function in the thermostat. The interface is a bit wonky but it can be done. I plan to tell Ecobee that they should allow for settings lower than 0F.

 

[EbS-P]

To be honest I'm not sure but I couldn't seem to disable the function. I was going to suggest that as a software change to Ecobee for future updates.
As of now, I assume if the temps drop below 0F my HPs won't work.

Edit: I just emailed Ecobee support. We'll see if they're responsive.

I don’t know how those are wired ie are the wires easy to access, but at those temps I imagine the heatpump would not cycle. In that case overnight you could just pull off the thermostat and jumper the correct wires so it would appear to the heatpump that the thermostat was still/always calling for heat.

 

[semipro]

I don’t know how those are wired ie are the wires easy to access, but at those temps I imagine the heatpump would not cycle. In that case overnight you could just pull off the thermostat and jumper the correct wires so it would appear to the heatpump that the thermostat was still/always calling for heat.

I thought about something similar. For me, it would be easier to do it at the outside unit.
Since I figured out (above) how to disable the compressor lock-out function on the thermostat I should be good now. The outside unit should have its own protection for very low temp operations.

I just posted in case my experience would benefit other Ecobee users.
I've been very happy with the Ecobees. The ability to control them from my phone and smart home systems has been great.