+whatever we are at for letting the HVAC install the stats and own any issues moving forward. We had a job we did HAI tstats in. Got a call from homeowner saying it does not work in one zone. Of course I stopped by and checked voltage at the stat. No voltage on common. We had the HVAC guy hook up commons on all stats from the beginning. I had to open up his panel and test the 24VAC transformer. It was dead. I had her call her HVAC guy while I was there and let me explain what I had found. I then charged her for me figuring out his problem for him. :)

We normally use Aprilaire 8800 stats and RS232 hub for control. We do not even source the hardware. We just tell the HVAC contractor what to install. Once it is installed and working, we connect to it. Period. Same with security systems.