hooking up custom thermostat control to my hvac air handler

[completelyhis]

I'm finally getting ready to hook my HS setup up to my HVAC air handler (with a custom setup of devices, relays, etc), and I need your expertise! Here are my questions: The existing thermostat wires hook up to the following: What are they?

C
G
Y
W
R

"Y" has two wires connected to it...yellow from the thermostat, and White from a pair...the other one on that pair is red, and goes to "C".

Ok, next. When I was fiddling around with the connectors, I accidentally pulled one of the wires off the post the connector was pushed onto. There are several options of where it goes. It is a black wire that disappears (with most of them) behind the blower motor. I'll take a picture of the connecting block and you can tell me where you think it goes? the picture will be on my Facebook page.

Let me know what you think. Thanks very much!

[cadillackid]

the black wire from the blower motor is typically the High speed fan hot wire.. (if it in fact goes to the blower motor).. this is usually on the terminal marked "cool fan" on the terminal block... however it may be on a post marked "spare" if the original installer didnt use the High fan speed for cooling.... I have no idea what your facebook page is so I cant go look at the pic..
-Christopher

[completelyhis]

christopher,
thanks very much, that confirms my gut feeling. another problem i'm having is that the rain8net zones i'm using for Y, G, and W are not making anything happen. i think that's because i by passed the 24vac transformer to use the one powering my rain8, but it didn't work. now i'm thinking of running the 110v from the air handler to power my xformer (7.5 amp, 24vac) and then running two lv wires from the R and C, to power my rain8.

thoughts?

[mwaite]

When I installed my Insteon Thermostat I did some digging to find the attached diagram. My old thermostat did not have the 24VAC ground wire attached because the analog thermostat didn't need it. I found I could connect it in the attic where the HVAC terminal block is.

[Stuart]

I kind of had a similar problem. One thermostat no 24v common and the air and heat were two separate systems. I ran a 24vac supply in the cellar with a pair of wires to run the zwave thermostat. On the thermostat I cut into the circuit board and isolated the relays from the 24v supply on the board. I added return wires for each relay. So when the thermostat calls for heat It connects the R and W. for cooling it connects Rc and Y for compressor, and the Rc and G for the blower(only one speed, tied both green and grey together.) The existing thermostat was one of the round honeywells.
If you are running off the rain8 relay dont forget that there are compressor timeouts that you dont want to restart I believe for at least 2 minutes.
Stuart

[cadillackid]

the hardest part about doing direct HVAC control is the safeties... sure the equipment has some of its own.. but quick 3 second power outages or surges are literally destructive to compressor based equipment (heat pump, A/C) that is why I use controllable thermostats so that I retain time delays and retain some sort of HVAC even in a failed computer state... A/C im not worried about but heat I am...

so my fancy blower speed controller knows to kick on the blower at 50% speed if the comms to the computer are severed... and my Ocelot makes sure that the furnace enable in low stage is available if one of the zones goes cold... a mechanical thermostat will kick in low stage fire on the furnace if all means of control fail.. and a 165 degree thermal will kick the blower in as well.. so that if the homeseer system fails.. and all the zones are set to Off and the house drops below 48 or so the furnace will come on to keep things from freezing...

as stable as we like to consider our HS computers they do after all run a variant of windows and windows PC's do lockup, go belly up or just plain blue screen without reboot...

another device i have is called a "cyberpower" and it is a power strip that each outlet can be controlled remotely... if the handshake between my linux based router and the homeseer server goes down... the homeseer PC can cycle power to the router.. (tries 3 times 30 minutes apart)... OR the router can cycle power of the HS PC (tried 3 times 30 minutes apart)... its lovely because they watchdog each other....

-Christopher