24Vac digital inputs?

Troubleshooting
1

Hi,
I’m trying to use the inputs as digital inputs in a 24Vac circuit (ie: is there a call for heat on a Tstat?) on my T3-TB. Seems like a common use case for such a controller but it’s acting crazy so I’m wondering if it’s supported, or if I’m doing something wrong.
I’ve 4 inputs, all bussed together on one side (to common), and to one Tstat output on the other side.
They are set as the following in the T3000 software:

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While the Tstat is not calling, I’m getting the inputs to intermittently trigger (even after doubling the filter value)
I removed all the Tstat wires (keeping the common side wired together), and noticed the following:
If I remove all the Tstat wires however, none of the inputs triggers (as expected)
if I connect only one input to the common then the led turns on.
if I connect the same input to 24Vac directly, then the led start randmly blinking, along with the other inputs that are not connected
(see it in action in that poorly filmed clip)
This crazy acting makes me think I’m doing something I’m not supposed to… Does the controller only support DC source for digital inputs?

2

The inputs are not set up for monitoring 24vac. They can do DC voltages and the maximum voltage is 0-10v.

The quickest fix for now is to put a 24vac relay on the 24v circuit and monitor the low voltage side of the relay.

3

Too bad, this wasn’t clear from the brochure… I expected a HVAC targetted controller with “universal inputs” to be able to handle 24Vac.
Would be good to provide an add-on module for it at least (similar to the AO 2 DO one).
I should have enough room for those 4 inputs on my relay board for now, but it means I’ll probably have to make another relay board fit in there in the future.