I posted this over on Smarthome's forum, but thought I would try here as well.

 

I just installed two Venstar 2491T7E's with the built in Insteon adapter. Both thermostats have a pretty considerable humming noise coming from them. It is audible from abuot 3 feet away. Anyone else experiencing this? Is this considered to be "normal"?

I am experiencing this as well. My first thermostat lasted about three months but did not recover from a power outage , it was version 2.2 and worked fine until that happened. I got a replacement (v2.3) and I noticed this hum a day after it was in operation. I have tried power reset and factory restore but nothing has fixed this problem. IIt has been a while since your post, have you learned anything or have you had it replaced?

I have determined the hum is only present when the LCD is backlit. I contacted Venstar directly and they said if the thermostat is making any noise then it should be returned for a replacement unit. I am now waitng for my replacement.

New thermostat installed and working fine, no hum or buzz. The previous unit was defective.

 

 

Brian