geoman jr wrote:
Remember the flow throughs only work when the furnace fan or burners( in
some cases) are running. If your furnace is not getting much run time, guess
what, your not putting humidity in the air. Running your fan all the time
might help a little but then you'll be paying more in electricity. Gofish
has it right !

I am not disputing what Gofish said.

My original observation was that the General Aire 81 (evaporative pad), connected to the cold water supply was more than adequate while the Wait 6000 (flow through), connected to the hot water supply did a lousy job.

Steam humidifiers are something that I am not familiar with.
I have to find a distributor in the Toronto area.