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[RSI]

This might help  http://www.doityourself.com/forum/heat-pumps-electric-home-heating/279666-trane-heat-pump-tstat-replacement-honeywell-prog-wiring-question.html

I have been looking at a bunch of different websites and can't figure out what the W is doing on your setup.

Y turns the compressor on
G turns the fan on (manual setting but apparently there are a few electric systems out there that need the thermostat to energize it in all modes)
O is the reverse valve (o/b on new thermostats)
X2 second stage heat (w2 or aux on new thermostats)
B is the common (C on new thermostats)
R is the 24v supply
Everything I have seen said to just cap the F and T wires but not sure about that.

I can't figure out what the W wire is doing on yours.

The aquastat on your system in just disabling the compressor. If you ever put in a bypass so you can heat the DHW the A/C will also be disabled unless you put the bypass before the aquastat.

[Ridgekid]

I read the link you just posted. That looks like the answer I needed to go digital. W looks like its my aux heat. In this case my heating strips.


Now to find a thermostat.

[RSI]

That is what is confusing me. Do you have more than one type backup heat? It looks like the W should be the heat strips but then x2 is emergency heat.
Maybe it just doesn't do anything on yours?

[Ridgekid]

Aux heat is when heat pump goes into defrost mode or we turn the thermostat up more than 2* and it assists the heat pump.

Emergency heat is aux heat only because the heat pump has a problem.

Does that help?

[RSI]

I guess.  Lol
But why would the thermostat have different wiring for it? How does the thermostat know if it is having a problem?

[Ridgekid]

Sorry I don't know. Could it be a feedback signal from heat pump??  We have had a red light (emerg heat) come on before. And it was a heat pump problem 

[RSI]

Ok, that makes sense. The x2 is probably just a wire to turn that light on. It probably sends the signal to it when there is a problem.

[Ridgekid]

Well I searched well past my bedtime and found a cool looking thermostat. Ecobee. But where did I hear that name before?  Oh yeah from Gmviso!

Gm- stock your wood burner and grab your coffee. We need to talk!

[yoderheating]

If you want to block multiple wires using a aquastat the easiest thing to do is use a double throw relay. Run power ( red wire r terminal) to the common of the aquastat and then run a wire from the NO to activate the relay. If you run both the wires from the w and y terminals through the NC part of the relay it allows both to be blocked when the aquastat is activated. 

[Ridgekid]

I talked to gm this morning and he actually recommended the Prestige. Then, while I was searching, I ran across three more :
comfort link II ( too expensive)
venstar
Schlage link.

If I ( knowing me its probably when I) expand my home automation, I'm sure the Schlage link would be the easiest to tie into my system.

What are others using and your thoughts?

[Ridgekid]

Doesn't look like the Venstar is smartphone compatible. One down three to go.