We recently had a Trane XC95/XL16i furnace/heatpump combo installed along with a Honeywell HM506 Truesteam humidifier. After several issues with the installation the humidifier is finally working. However, it is unable to raise the humidity level. There looks to be a sizing issue (based on Honeywell documentation and our house size of 2500sf), but I'm also curious as to the air flow of the furnace blower when the furnace is not running and if it is sufficient on low speed to deliver humidity into the house. I've been searching online without success but did notice a Honeywell sail switch for use in similar installs (S688A1007). I'm thinking this switch would turn on the humidifier only when the blower is at a higher speed, but doesn't seem like this would do anything for moisture delivery, only reduce the times the humidifier is running to only when the furnace is on. So my question would boil down to: will a variable speed furnace running on the lowest speed push enough air flow to carry moisture from a steam humidifier into the house or would the furnace need to ramp up to a higher velocity to accomplish this?