We just bought a new (to us) house in Calgary, Alberta. Its a 2 story, built in 2007, 5,000 ft^2 finished, including the basement, 9 foot ceilings throughout. Hardwood everywhere on the main and upper floors. Finished in place floors, hard wood built ins, solid hardwood doors. Its appears to be a very well built home. Its probably pretty air tight.

Calgary is extremely dry in winter. Its dry when its cold out (-20F) and even dryer when the chinook winds roar through. Think 32F, 30 MPH winds, 10% relative humidity.

The house is deficient in humidity. The hardwood in the floors has shrunk slightly. We've been advised to do something about the humidity problem ASAP or risk long term damage to the floors.

The house has an on demand natural gas hot water heater and hot water storage tank feeding heat exchange coils in dual forced air heat exchange units, one for the main floor and one for upstairs. The basement has its own recirculation fan and ducting and in floor hot water heat coils.

The house also has dual AC.

The forced air heat exchangers are each equipped with Honeywell drum type evaporative humidifiers with simple local humidistats.

What should we install in this house to maintain the humidity at 30% or more through the worst conditions Calgary has ?

Thus far the best option seems to be dual AprilAire 800 steam humidifiers. I'm liking them over the GeneralAire steam unit because of the controller and the fact it starts up the fan to sample air humidity from time to time and its got an outside temperature sensor.

However, these units seem to draw a lot of electricity ! Is there any way to humidify this house with an evaporative humidifier or is there such thing as a natural gas steam humidifier ?