Bypass vs. powered question

I've seen a lot of people asking about which side to hook up their bypass humidifier. Am I correct thinking it doesn't matter? That no matter what the air is going to move from the supply side to the return side so no matter which side you put the humidifier on the humidified air is going to be delivered to the return air side? If this is the case then my question is wouldn't a powered humidifier on the supply side be better? My thinking is that all sending the humid air through the heat exchanger is going to lead to rusting and premature failure of the heat exchanger. Where as if you put a powered one on the supply side the air will go to the house and have a chance for the humidity to drop considerably before returning to the furnace. What are your thoughts? BTW, I am installing a 95% efficient furnace and will be putting on a humidifier.

 

No, it really don't matter.. most of the Pro rather see it on the return if there is room. Why the return? If you have water problems with the humidifier, you won't get water on the heat exchanger, and/or controls.

The main reason why the powered unit is better on the is that the air flow is already warm, with the warm air, the water will evpaerate much better than the cool air.

The humidity isn't high enough to cause any rusting to the heat exchanger.

 

Thats why about the only humidifier we sell and install is the power Aprilaire 700 It does the best job. Right on the furnace plenum.

 

Ok guys, thanks for the answers. I hadn't thought about the possiblity of a malfunction causing problems. I'll definetly keep that in mind. However due to space limitations I may have to put it on the plenum anyway. Again, thanks for the help!