meirman wrote:

...it's more efficient to boil water on the stove and raise the humidity
in the house. Efficient in that you will feel warmer for the same amount
of fuel.

Nonono.

http://lennox.com/pdfs/brochures/Len...umidifiers.pdf used
to claim 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but
the the ASHRAE 55-2004 comfort standard says 69 F and 35% RH and 69.8 at
9% RH are equally comfortable (PMV = -0.542.)

If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance,
turning the thermostat down from 69.8 to 69 saves (69.8-69)400 = 320 Btu/h.

Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per
pound of dry air, so 19% air has wl = 0.00301 and 39% air has wh = 0.00617.
Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds
of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.

With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 lb/h of air leakage,
raising the indoor RH from 19 to 39% requires evaporating 720x0.00316
= 2.275 pounds of water per hour, which requires about 2275 Btu/h of
heat energy, so humidifying this fairly airtight house wastes 2275/320
= 7 times more energy than it "saves." Many US houses are less airtight,
so humidification would waste more energy.

Nick