24VAC Inputs

Input Signals and Configuring
1

I have an Honeywell T9 that work as the main thermostat for my heat pump, however when I need second stage heating (because outside temperature is too cold), I would like to link the Honeywell to my T3-BB, so that I can start my secondary heating.

My thermostat have the usual W terminal to request secondary heating, but was wondering if I could use that directly as an Input or if I need something to lower the voltage first.

1 Like
2

The outputs of the Honeywell will be 24VAC whereas the T3-BB inputs max out at 10VDC. You would have to put a small 24VAC coil relay on the W terminal and wire the contacts to one of the inputs on the T3-BB.

3

Will buy a small relay and see if it work, thank you