On Sun, 17 Oct 2010 08:22:54 -0500, The Daring Dufas
wrote:

On 10/17/2010 7:51 AM, Don Phillipson wrote:
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.


Newer stuff with DC drive motors for the air handler may run at a
very low speed continuously to even out the temperature of the home.
The first HVAC system I came across with this feature had me thinking
there was something wrong until I called the supplier and was assured
it was a normal operating mode. The best bet is to call the manufacturer
and find out if the continuous low speed is a feature of your new gear.

TDD
It is an available setting on virtually all currently available forced
air furnaces - and ALL DC variable speed systems.