Honeywell thermostat wiring scheme shows up as incompatible in the app. Anyone know why and is there a workaround?
No, I don’t see why the Wyze would not work, You may have simply answered a question incorrectly. Your old t’stat has standard wiring. I suspect though, that the Rc wire is your common, not a Hot for cooling. So, that could be the issue in answering the questions. To be sure, you will need to look at the main unit and verify that the blue t’stat wire does indeed terminal to a common at the unit - which could be Com, C, Gnd, or simply attached to the metal of the unit.
Once verified, you should be good to go, and you won’t need the CWA (common wire adapter).
It’s incompatible because you have a separate Rc and Rh wire, but no C wire. The C adapter wont work in this case, because the G and the Y wires do not use the same transformer.
I’d check the wires in your wall to see if you have an extra one that you can attach to the common side of the Rc transformer.
Speadie is likely correct also. After you check the inside & outside units to truly identify whether the blue and red wires are both Hot (24VAC) sides of transformers, you can decide how to rewire things.
If the main unit and/or outdoor condensing unit have been replaced in the last 15 years, you likely don’t need two transformers to make things work. The main unit transformer, while small, can usually handle the additional current of the outside units’ contactor/relay.
In the old days, the traditional 24VAC transformers used were less than 40VA, meaning they could only handle less than 2 amps of current. And, the older relays and contactors were big on current draw. Hence, two transformers were needed.
With upgraded units, the indoor unit circuit boards have on-board relays that all combined draw only about 0.5amps. You can look at the outdoor units’ contactor/relay’s rating; it should be about 15VA, or 0.625 amps. Thus, you’re looking at a total of about 1.025 amps, or 25VA (in-rush not included). This is completely inline with a single transformer application.
So, you could abandon Rc and use a setup that would have been like “Rc is jumped to R”, thus letting the Wyze thermostat supply power out to the condensing unit contactor as needed. The blue wire can then be re-used and connected to common on both ends, or you can use the CWA kit.
Of course, it’s up to you, based on your knowledge of wiring, etc. Always double check everything, do your voltage checks. Also, have a spare fuse on hand just in case. Most newer indoor units have fuses that are like a car fuse, generally rated at 5 amps. You can pick them up at any automotive center.
Also refer to page 42 of the installation manual for dual transformer control and wiring. Their explanation is clear and achievable for your basic installer.