Ecobee Issues

[Brucekane]

I have followed John Canfield's lead and replaced the Coleman-Mach thermostat with the digital Ecobee in my 2005 Itasca Horizon. The advantages of the Ecobee are many but the huge disadvantage is the inability to force Stage 2 (gas heat) without inabiling stage one (heat pump). This issue is of importance when dry camping or when plugged into a 15 amp outlet. John told me that a work around involves going into "test equipment". However, in this mode,the heat only stays on for 30 seconds or so in this sertting and fiurthermore, both stage one and stage two activate in this test mode. So my question is: does anybody know how to force stage two ONLY with the Ecobee?

[John Canfield]

You can add a dumb thermostat like is used for the rear furnace and switch +12v to the furnace (was that W2 - I forgot.)

[Brucekane]

So are you suggesting that I remove the lead W-2 and run it to a dumb thermostat? In that case, the gas furnace will run completely independent of the heat pump and will fail to turn on except only manually. A worthwhile trade off in my book. Too bad it can't be worked out any other way.

[John Canfield]

You can just tap on to W2, it's just looking for +12v either from the ecobee or whatever else. I can't think of any issues if the ecobee and a dumb thermostat call for the furnace at the same time.

[kdbgoat]

Swap the wire from stage 1 to stage 2 and vice versa. The furnace would be stage 1 and the heat pump stage 2. Or put a small switch in the stage 1 wire to keep the heat pump from being enabled.

[Brucekane]

I tried the suggestion of a switch to the stage 1. The blower still came on without heat and the furnace failed to activate in the minute or so of my trial. So it off to their hardware for a thermostat. I assume that I bring power into the thermostat from the red wire and send the power out to the white (W2).

[John Canfield]

Think of the ecobee as a programmable switch with 'dry' relay contacts (this is one reason why it is perfectly suitable for this application). When the ecobee calls for 2nd stage (emergency) heat (propane furnace), the ecobee internal relay for W2 makes contact and sends +12v to the W2 lead. All you are doing is basically adding another 'switch' across W2 to provide +12v.

That reminds me, you need a really, really simple thermostat exactly like the one used for the vent fan and the rear furnace, otherwise you will need to tinker with the guts of the typical AC/heat thermostat like you would find in a hardware store.

[Brucekane]

I wired a simple “heat only” circular thermostat as follows:
Red wire (fourth from the left on your illustration) which is +12v going to red on new thermostat
White wire (first from left) going to “W” on thermostat.
The Ecobee is set to system off and new thermostat is set to 80 degrees. Nothing happens. I am afraid of changing the Ecobee to call for heat as it will engage the heat pump. Any suggestions?

[John Canfield]

On the heat only thermostat you added with the wires in place:

1. Verify you have +12v on red
2. If you have 12v on red, jumper red to white, gas furnace should start
3. If furnace starts, then you have a thermostat issue of some sort, that's why I said to use the exact thermostat the fan and rear furnace uses

[Brucekane]

I’m taking the thermostat back because when I touch the two wires going to the new thermostat together gas furnace starts but does not start otherwise. Not sure where to go from here as this one does not seem compatible with my system. Thanks for your help.

[John Canfield]

I tried to hack a hardware store basic thermostat to serve a similar function and I was somewhat successful but consider it a general failure.

[Brucekane]

Do you think my problem is the lack of a “common” lead going to the hardware thermostat. According to the schematic, the first and second stage heat seems to call for it. I am afraid to try it without asking your opinion first.

[Brucekane]

The other observation is that with the red +12volt  lead and the white W1 lead touch, the forced air of the gas furnace come on but I have not yet heard the gas furnace ignite. That is leading me to believe that it needs a “common”.

[John Hilley]

You probably don't need a common. The dumb thermostat should just be a thermal switch, usually bimetallic or such. Adding a common shouldn't hurt. It should just pass on the 12 volts when it closes.

[Brucekane]

I have one last observation:
The Ecobee works just fine in demanding stage 2 heat when dry camping without any modification as long as the following conditions are met.
1. Dry camping with NO shore input.
2. Inverter must be off.
3. One needs to wait a good 15 minutes with the thermostat set on “heat”.
You will see a note: “Temperature HOld Press Enter to Resume”. You must ignore this prompt.

So There!! The Ecobee works just fine. Just don’t ask for heat when connected to 15 Amp shore power. There is no way to get furnace heat without also activating the heat pump as long as Ecobee sees AC voltage.
I hope this is helpful to others that have made the switch to this thermostat.
Many thanks to all who have tried to help me through this issue.

[John Canfield]

That's an interesting observation. The ecobee won't call for stage 2 heat (gas furnace) until stage 1 heat (heat pump) is determined to be ineffective. I'm not sure what the presence of 120V has to do with the ecobee not calling for stage 2 heat, I'll review the operating characteristics of the Si.