A flow-through or drum humidifier is a question when an old humidifier dies due to its age, or cannot find parts anymore.
In installations that need a condensate pump I prefer a drum humidifier or steam humidifier. Neither of these units discharge water unless the float valve malfunctions. They do require more maintenance because of lime buildup from the evaporating water.
I have come to appreciate the flow-through humidifier because of the reduced maintenance it requires. It does have a few quirks that once addressed makes the unit operate more efficiently.
Install the unit on the warm air plenum that improves evaporation.
Attach the water supply to a hot water line for the same reason.
Not every installation requires this, but if the humidity in January will not get over 30% you may have a solution to that situation.
The only drawback I have with the flow-through humidifier is the amount of water that is wasted when the unit operates. On my mother’s unit, I throttle the water flow down with the shutoff valve by watching the discharge water through a clear drain hose. By reducing the water flow, I lower the humidity output, but also reduce the water waste.
In an installation where there is a condensate pump I check to see if there is a floor drain within reach. The condensate pump is for installations where there is no floor drain, or it is across a walkway, or it is too far away to run a drain line. It is not uncommon to find an installation where a condensation pump is used and a floor drain is within easy reach.
My question is why pump water that will drain by gravity without a pump?