"Ken Hrynchuk" wrote to "Roy J. Tellason" (21 Dec 02  07:09:00)
 --- on the topic of "Furnace fan?"

 RJT> There should also be the option to make the fan run continuously
 RJT> for those setups that are equipped with a/c also.  I've seen it
 RJT> recommended that this be done for heat as well as a/c,  not just to
 RJT> lengthen the time but to keep it running continuously,  it's
 RJT> supposed to actually lower your heating costs.

One thing to consider is the chimney flue temperature of a properly
burning furnace. If the temperature is a bit higher than 500'F then the
exchanger fan could be speeded up slighty so the air flow can extract
more heat instead of wasting it up the chimney. Often the motor on the
fan has a variable diameter V-shaped pulley which can be adjusted by
opening or closing the V to alter the fan's speed.

However, keep in mind that the fan motor controller is already set for a
certain range of temperatures so that changing one setting will likely
affect another. The changes should be very minimal and done one at a
time so their individual effect can be observed more easily. Always
document the initial settings and the changes made with the results.
The overall efficiency has to be re-evaluated as each change is made.
Because there is more air flowing, the air temperature at the grill
should not drop by more than 10'F or be easily noticable in the room.
Sometimes it's possible to use a smaller diameter nozzle on the burner
to increase efficiency but this requires a completely new tune-up.

 Mike
 ****

... 'Keep the smoke inside.' -- 1st Rule of Electronics.
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