Thermostat Confusion

In 2020 I will be replacing both of my HVAC systems at home. I haven't yet decided on the brand of EQ, but from reading many posts here the consensus seems to be the Trane 624 thermostat as the best NON-CLOUD choice.

Here is my confusion, since whatever EQ brand I buy it obviously needs to be controlled by Indigo. This seems backwards but I feel that I need to select the thermostat FIRST and then select a brand HVAC EQ that works with that thermostat.

But from what I read in a recent post the 624 doesn't work with newer modern EQ such as 2-stage, variable speed, etc. So what thermostat are we suppose to use?

For those of you that are currently using the 624, what type and brand of EQ are you using? (Single stage, 2-stage, variable speed, heat pump ...) Am I wrong regarding the 624?

I currently have:
5 ton, split system, single-stage, Venstar Stat
1.5 ton, heat pump, Venstar Stat

The upgrade will be at least a 2-stage, or most likely a variable speed which is what most companies seem to be offering.

My fear is that I drop 20k and not be able for Indigo to control it. The HVAC installers don't understand HA, and the manufacturers won't talk to you and refer you to the installers.

I need to get this right - HELP

What is EQ? Equipment? I've never seen anyone use that term. If I need something short, I usually use HVAC.

I believe the XL624 will work with two-stage equipment. I have a brochure right here, and it says 4 heat and 2 cool stages. It will not do variable speed. At least not using Trane equipment.

I'm about to replace my Rheem 5 ton single stage system with a Trane variable speed using the XL850 thermostats (2 of them). Those will not connect via Z-wave to Indigo like the XL624 will. My plan is to write a plugin to communicate with it using the cloud service. This gives me the same functionality I currently have with the Ecobee thermostats I have now.

I do not think you're going to find any variable speed system that's going to use thermostats that can be directly controlled by Indigo (via Z-wave, etc).

Due to house design and the issues we had with the original system (less than 4 years old), my priority has to be getting a system that'll work right for the house. Indigo compatability has to come after that.

Our downstairs unit is 2-stage and our upstairs unit is single stage. I use 624s to control both of them.

More confusion that I can't seem to get the answer to.

Trane XL624
American Std ACONT624

I have been told that the two above stats are exactly the same with different faceplates, so my questions pertain to either one

1) I have read many reliable comments from owners warning that when these stats loose power [outage] they default back to GAS & Std AC. This is pretty serious if you have a HEAT PUMP! Trane & AS refuse to speak to the public and the dealers I've called either guess or say they don't know.

2) I have been told that there is a USB port on the back. If that is used to update firmware, how is that done if you are not connected with NEXIA?
Can you save all config settings to a flash drive? How is that done?

Any info users can share would be greatly appreciated.

I'm afraid that I can't respond to either question. My units are gas and standard AC, and I've never had a reason to update the units' firmware.

I hope you find the answers to your questions!

the honeywell unit that I bought about a year ago works with multiple-stage heat and cool stages. It is their T6 Pro z-wave model. it is well-behaved. senses and reports humidity. it has z-wave+ support. generally a solid unit. you can find it for about $125.

configuration/installation details can be found here: https://forwardthinking.honeywellhome.c ... -00294.pdf