I asked a question about installing a new Honeywell thermostat to an old system My system (old coal converted system) has a Homart(Sears) thermostat that has only 2 wires to the thermostat. I am now replacing this with a programmable Honeywell RTH2510. The answer was as follows.

Follow the directions in the thermostat box. All you need to connect is the R terminal to one wire and the W terminal to the other wire. Install batterys and follow the setup schedule.

I did this and the gas furnace heater kick on, but the blower fan does not.
What to do?

Possible still have a setup problem, with the tstat