Tuesday 25 January 2022

Ecobee4 Wiring 2 stage Rheem Furnace + Ac + Humidifier

We had a Rheem 96V 2 stage communicating Furnace installed in 2016 with what I believe would be a communicating thermostat.
In 2019 we had a Goodman whole home single-stage AC unit installed that came with an Ecobee4.
It came to my attention only recently that the humidifier was not functioning.
The first thing I realized was that the Ecobee was not wired to control the humidifier. No wire in Acc+
I then read through some of the wiring diagrams to see how this should or could have been wired up.
There is no humidistat wired to the humidifier at the furnace.
I figure the original communicating thermostat controlled the humidifier previously.
Due to this error, I started to read up more and check out the furnace manual for wiring configurations for the furnace as well.
I then started to question whether the 2 stage furnace was wired correctly to the Ecobee.
From what I read on the forums It could be wired a couple of ways.
Currently, the Ecobee sees the furnace as 1 stage furnace with no control over the 2 stages.
So that would mean the furnace should control these 2 stages.
That is fine with me as long as this is the best way to go about it with this ecobee4.

The furnace is currently wired to the furnace as a legacy 1 stage thermostat with auto staging.
The dip switch for Normal 2 stage operation (auto staging is off) and currently auto stage is set to 10 min on low then to high with call on "W1"

The Ecobee is currently wired with 4 wires using the power extender to give power to the Ecobee.

I had an HVAC service guy come in to verify this setup and he agreed that I would need 8 wires to the ecobee to control the 2 stages and the humidifier.
He did not have the wire and just wired the humidifier to come on every time there was a call for heat.

The next day I disconnected the humidifier as this was too much humidity for the cold temps here and the windows were frosting up quite a bit.
Definitely need some control over that humidifier.

With this information, I understand I need at least one more wire to run to the ACC+ on the ecobee to control the humidifier
The thermostat wire was originally a 5 wire but the 5th wire was cut off during the initial installation at the thermostat. I don't think there is enough slack to tap into it now.

Should I run another 18/4 wire and wire the furnace to Ecobee as two-stage plus the humidifier or should I just run another say 18/2 and just connect the humidifier?

Would the humidifier be wired to the ecobee with just one wire? One wire to "C" terminal and the other to Acc+ on the ecobee?
I see there is a wiring diagram for a 2 wire setup to the ecobee? See attachment.

When the last tech was here he removed a 24volt transformer that was installed for the humidifier and just ran the wire from the humidifier to the "C" terminal" Is this ok?
I see a couple of terminals marked HUM on the bottom of the furnace PCB are they to be used to power the humidifier or the c" terminal is fine?

If I do wire the Ecobee as a 2 stage do I need to make changes to the dip switches with regards to the auto staging?
Are there any dip switch changes required for the humidifier? I see a note on the wiring diagram regarding turning dip switch s2-8 on. Turning this off would disable dehumidification with a non-communicating thermostat. Factory set to off. See attachment.
Does this need to be on?

The attachments show diagrams of how the furnace is currently wired along with some schematics of how I think it should be wired for a 2 stage furnace to the ecobee as a 2 stage.
As well attached the description of the dipswitches I mentioned.

Let me know your thoughts.

This is how the furnace is currently wired up. Please don't mind my messy drawing. :gah:

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This is the wiring diagram from the furnace manual of how I think it is currently wired 2 stage furnace and 1 stage thermostat.

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This is the ecobee4 wiring diagram that I think should be used for the 2 stage furnace with 2 stage thermostat.

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This is the wiring diagram in the furnace manual for wiring a 2 stage thermostat like the ecobee that I think I should use?

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This is the wiring diagram from the furnace manual for the humidifier. Not exactly the configuration that I have. So I'm not sure?

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This is the ecobee humidifier wiring diagram for 1 wire and 2 wire. I think I just need to use the 1 wire setup?

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Name: humidifier 2 wire ecobee.JPG Views: 12 Size: 65.9 KB


This is the info regarding the 2 dipswitches in questing regarding auto staging ad dehumidification.

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Name: Autostage dip switch.JPG Views: 12 Size: 37.9 KB


This is the dip switches on the furnace board.

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source https://hvac-talk.com/vbb/threads/2235867-Ecobee4-Wiring-2-stage-Rheem-Furnace-Ac-Humidifier?goto=newpost

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