But it's not supposed to. Burner is supposed to light for a minute or so then the furnace itself turns the blower onto low. Instead it appears that when the tstat turns heat on both the Y (Blower high speed) and W (Gas valve) contacts get closed to the common and it should just be W closing to C.

This is a single stage system at my own house. Two actual industry guys say it's hooked up right but that all thermostats have a dip switch or jumper on the back to designate electric or gas heat (fan goes on high same time on electric to keep heating element from self-destructing). But I cant find any switch on it or in the manual and support doesn't seem to understand the real world side.

In TC programming there are lots of settings but nothing that seems to apply. There is a choice for system type but gas and electric are within the same choice.

Interesting - I don't see any signs of this being a setting choice. I guess they just didn't see the issue with a bit of cold air coming out the vents.

Seems like it would be an easy firmware change to implement, though.

I got the case escilated and turns out it's just made that way and no way to change it. Fascinating the product has been out this long and this is the first time it has seemed come up.

The other thing other than cold air at first is that with gas heat the blower is supposed to run on low. The THZ was making it run on high which is actually counterproductive as far as efficiency.

Great news I fingered it out. I had all but given up, started thinking about just using it downstairs where we have some radiant floor heat, and it occurred to me....
Simply lie to Accelerator and tell it you have RADIANT HEAT. With radiant there is no fan so the stat behaves the way it does with gas and does not turn the fan on for heat, just the burner. The burner tells the fan when to come on not the stat.

Downloaded to the MRX and checked everything w/ a meter first and it works perfectly. A simple relabeling of the Accelerator dropdown choice would clear this up, but again, truly amazed to be the first person in the world to be aware this even happens. Other than that awesome piece!

Its because you are the only person in the world using that thermostat!? :)

Nope, the only person in the world who has brains to pay attention to the cold air coming through the vents. And knowing that, that isn't correct.

Great job in out tricking the high tech thermostat.

KOT

Calling a thermostat high tech that can't do what a $50 Home Depot one will is a bit of a stretch. It is a URC so to be expected.

I've pretty much figured out that none are really too high tech. They're pretty much a relay with three to five contacts that close under whatever conditions. I do try to stay away from the mainstream cloud based stuff when possible so when you check this status on any of the other interfaces you pretty much get an instant readout

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