On Sun, 17 Oct 2010 08:51:08 -0400, "Don Phillipson"
wrote:

"mm" wrote in message
.. .

Do low-speed fans on new warm air oil furnaces run all the time?

Furnace fans are commonly controlled by thermostat switches
with three settings:
Off = fan never runs
On = fan runs always
Automatic = fan runs when required by the heating unit.
And the VAST majority of new furnace installations DO run the fan at
low speed constantly when on "automatic" - kicking up to higher speeds
when heat or cooling are called for.
In most cases, AC blower is higher than heat blower speed.