Can anyone confirm success with LAN control of a T5 and if it was acquired through the Georgia Marketplace?
Any lessons learned would be appreciated
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I bought two of these Honeywell Home T5 Smart Thermostats (RTH8800WF20220) from the Georgia Power Marketplace and can confirm you can use it on LAN only (without internet). However you need a smart device with internet to set it up once.
To setup the device you need an Android or iOS device (with internet & bluetooth), have to download the Resideo app, and create an Resideo account. I couldn’t find a way to do this without their app, but the WiFi SSID I told it to connect to is on a VLAN without the internet, and it was ok with it.
- I am not an Apple person, so maybe you could do this without the app but with Apple HomeKit on an iOS device instead.
As soon as I got it to connect to Wifi I went into Home Assistant and added it as a Apple HomeKit Device. Pair code came right up and synced to Home Assistant!
- Even though you set it up as “HomeKit Device” in HA you don’t actually need an Apple device or account. I think the HA integration is able to simulate a HomeKit hub, as far as I know HomeKit certification requires the device work on LAN (AKA offline) too.
One small caveat is since I block the device from accessing the internet a small alert icon shows on the thermostat screen complaining doesn’t have internet but it hasn’t created an issue with HA. Been running it for about 2 days without any issues.
These devices have the Firmware: 5.0.4, and I have the following HA versions:
- Core2025.8.0
- Supervisor2025.08.1
- Operating System16.0
- Frontend20250806.0
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