I just got a new 7 DAY NOMA PROGRAMMABLE THERMOSTAT(52-2570-6). The old one is Honeywell t87f 3673
And the orig. wiring includes 5 wires: Y(orange), W(yellow), Rc(red), Rh(black) and G(green).
So I tried this: Y(orange), W-O/B(yellow), Rc(red), Rh(black) and G(green). When I turned on power, the fan just kept turning on and then turning off after 4 seconds.. . What did I do wrong? Thanks.

Some thermostats have jumpers you have to set according to your type of system. Look over the directions and make sure the jumpers are right.

I did as direction said: remove the jumper... I guess that tstat doesn't work for Honeywell