What would cause a gas fired forced hot air system to fire up without
the blower, then shut down. After the burner shuts down then the blower
comes on. Is this normal? Any ideas what would cause this behavior?
Can't replace the unit right now(No $$$). So I will have to repair or
have repaired. I just want to be an informed consumer if/when I have to
call for service. Many thanks in advance.

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ups.com...
What would cause a gas fired forced hot air system to fire up without
the blower, then shut down. After the burner shuts down then the blower
comes on. Is this normal? Any ideas what would cause this behavior?
Can't replace the unit right now(No $$$). So I will have to repair or
have repaired. I just want to be an informed consumer if/when I have to
call for service. Many thanks in advance.


It is typical for the furnace's burner to start first, then the blower. From
what you describe, on that age of furnace, my guess would be that the fan
control is either out of adjustment or shot. not really a big deal to
repair.
Then do yourself a favor and replace that old hulk as soon as you can. The
money you save on your gas bill will probably pay for it in a couple years!
Greg

Thanks for the reply. Sounds right on. I was just playing with the
Tstat. There is an adjustable arm behind the main control (this is the
round heat only style stat). After a few adjustments I think it will do
the trick. My father has a habit of playing with things like that, not
really knowing what he has done. I do plan to replace the unit with an
oil burning unit for both heat and hot water, using WVO or biodiesel
for fuel. Again, thanks for the reply.

"Thanks for the reply. Sounds right on. I was just playing with the
Tstat. There is an adjustable arm behind the main control (this is the
round heat only style stat). After a few adjustments I think it will do

the trick. "

The fan control Greg was referring to is the limit switch on the
furnace, not the thermostat. The fan limit switch controls the temps
that the plenum must reach for the blower to turn on or off.

I guess it's also possible as you suggested that someone could have
moved the heat anticipator in the thermostat to an extreme setting.
That apparently is what you are fiddling with. It's function is to
introduce some small amount of heat to the thermostat so that it shuts
off a little before reaching the desired temp. That way the remaining
heat in the system brings the house to the set temp, not overshooting.
At an extreme setting, you might be able to set it so that it shuts
off the furnace before the blower can turn on, but I haven't seen that
actually happen.