I have a red and a white coming from the fan and a red and white coming from the furnace. Which terminals on the thermostat (Y - G - W - R) are for the furnace and which is for the fan? Which is hot and ground for each?

Hot water heat, garage register has a fan attached to circulate the heat.

Red and white coming from the fan,, what fan are you talking about?

Most normal furnace systems should be


Red to r (hot wire from transformer to tstat)
White to w ( sends power back to furnace for heat)
Green to g (sends power back to furnace for the fan to run)
Yellow to y (sends power to ac
Hope this answered question

The g & y are my question. These run the fan. I have a red and a white wire coming from the fan transformer bringing the voltage in at 24v. My red wire from the fan is the hot wire. Does this go to the g or y connection on the thermostat?

I don't like these answers

R - Hot from 24 V transformer
W - Energize to heat (R connected to W)
Y - Energise to Cool (R connected to Y)
G - Energise to operate Fan (R connected to G)

(C) or Common from the transformer, provides the return path for the 24 VAC. It is also connected to (C) on the tstat is so equipped.