Lower flue temp is how high efficiency furnaces get their efficiency. Some
ammount of temperature is needed. On the older furnaces to create the
thermal lift to get the flue gasses out of the house. In moderately newer
ones, to keep the flue gasses from condensing in the chimney. The newest
furnaces with PVC vents, the flue gasses are cold already.

I predict that if you turn down the gas, y ou'll have other problems which
will more than use up your fuel savings.

Using your car analogy. You save 14% of the gasoline bill. However, by
driving slowly, the exhaust doesn't blow the noxious chemicals out of the
tail pipe. The corrosive combusion products eat up your exhaust system, and
you have to replace all the pipes. Further, the carbon monoxide isn't blown
out of the car. Your family develops flu like symptoms, and turns cherry
red. You are home from work for a week with killer head aches and two of
your children die from monoxide.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"JohnR66" wrote in message
...
I heard that adjusting the gas valve on my standard natural gas furnace will
make it more efficient.
By partially closing the gas valve reduces the flame. Although the furnace
would run longer, the flue temp is reduced meaning lower heat loss and
improvement in efficiency.

An analogy is like driving a car the same distance once fast and once slow.
When driving slower, it obviously will take longer, the engine is on longer,
yet fuel usage is less.

I have no way to verify if this is BS or not.