Mike Ross wrote to Ken Hrynchuk on 12-23-02 00:58:
 
 MR> One thing to consider is the chimney flue temperature of a properly
 MR> burning furnace. If the temperature is a bit higher than 500'F then
 MR> the exchanger fan could be speeded up slighty so the air flow can
 MR> extract more heat instead of wasting it up the chimney. Often the
 MR> motor on the fan has a variable diameter V-shaped pulley which can
 MR> be adjusted by opening or closing the V to alter the fan's speed.
 
Very interesting, Mike. How far up the flue would one make the
measurement? At the bottom, where the furnace outlet enters the chimney
proper?
 
 MR> However, keep in mind that the fan motor controller is already set
 MR> for a certain range of temperatures so that changing one setting
 MR> will likely affect another. The changes should be very minimal and
 MR> done one at a time so their individual effect can be observed more
 MR> easily. Always document the initial settings and the changes made
 MR> with the results. The overall efficiency has to be re-evaluated as
 MR> each change is made.
 
That's exactly the approach I'm taking. So far, my results have been
far from linear. My recent 2 degree decrease has had a much greater
effect than my previous decrease of 2 degrees. My initial 2 degree
decrease had a very negligible effect. I'm going to leave it where it
is, for a while, and observe (and wait for my next ga$ bill).
 
 MB> Because there is more air flowing, the air
 MR> temperature at the grill should not drop by more than 10'F or be
 MR> easily noticable in the room. Sometimes it's possible to use a
 MR> smaller diameter nozzle on the burner to increase efficiency but
 MR> this requires a completely new tune-up.
 
Thanks for all the info.. I haven't noticed a difference in peak
temperature at the vent, thus far. Temps. at fan-on and fan-off have
lowered somewhat, though (which is what I was after).
 
 MR> ... 'Keep the smoke inside.' -- 1st Rule of Electronics.
 
A la Asimov, may I make a suggestion?:
 
1. Keep the current from flowing across the heart.
2. Keep the smoke inside.
3. Make the electrons flow (unless doing so conflicts with #1 or #2).
 
   Ken
 
*** MultiMail/XT v0.41

--- TriToss (tm) Professional 11.0 - #108