Best Programmable Thermostats

As we move into the fall humidifier season, one question that gets asked a lot has to do with our advice on water temperature. When given the choice, why choose hot water over cold water to run to your Aprilaire humidifier
?

There are three main reasons. The first is performance. Our furnace-mounted humidifiers (except the drainless models) can get a performance boost by supplying hot water. We would recommend up to 140°F water to see up to 30% increased evaporation. For example, a model 600M humidifier on a furnace with 120°F air and 55°F water should evaporate 0.7 gal/hr for each hour it runs. By increasing the water temperature to 140°F, it boosts that 0.7 by 30% (.21 additional) for .91 gal/hr. Over the course of a heating season, estimating total usage at 600 hours, this translates to an additional 126 gallons of water put into the air.
 

The second reason is comfort. The more quickly the humidifier adds water to the air, the more quickly the air feels comfortable. This eliminates common complaints about too-dry air, itchy skin, dry, sore throats and static shocks.
 

The third is cost. This is often a sticking point. Does it cost more to heat the water with your water heater or to use the additional furnace and humidifier run time to increase humidity? Well, at 0.7 gal/hr, it takes the humidifier an additional 180 hours of furnace run time to create 126 gallons of evaporation. The water still needs to be heated so that it will evaporate. Is it more efficient to heat it with your HVAC system's hot air or with a water heater? Most likely it’s your water heater. Over the course of the humidifying season, the humidifier is evaporating the same amount of water, but by using hot water, it’s actually using less water to reach the same amount of soothing evaporative vapor.