On Sat, 23 Jun 2012 23:20:19 -0700, mike wrote:

On 6/23/2012 10:47 PM, Winston wrote:

(...)

Interesting approach. Somehow I'd not considered that my water heater
and space heater run at a fixed consumption rate when they are on.
Yes, once you confirm what that fixed rate is, what it says on the tag
ain't always what you get, you still have to determine when they're on.
I elected not to try to put wires into the furnace controller. Sensing
the fan let me put the sensor right were my electronics sat.

Perhaps I'll put an IR photosensor aimed at the burner.
Or a thermocouple nearby. Haven't decided.

Thanks again.

--Winston