Humidifiers and Dehumidifiers - Aprilaire 600A installation location

I am installing an Aprilaire 600A humidifier on a Carrier oil-fired furnace. The instructions say I can install on either the supply or return side with no preference. I have read elsewhere that the return side is preferred, but I have not heard the reason. In any case, if I install on the return side, I would have to fit the bypass with 2 ninety degree bends. Would the benefit I get from using the return side be negated by having two bends instead of one? Does it matter?

Thanks.

Reason for why lot of prefer this on the return is that lot of the newer furnaces are loaded with electronics, and if there was any water issue with the humidifier itself and have the water go down into the furnace, and down into the control panel will not be a pretty picture.

If you have an old oil furnace, there's not much in them so You can put it on the supply if you want.

Thanks for the quick response. I do have one followup question. On the carrier unit I have, immediately above the furnace, there is about a foot and a half of insulated ductwork that appears to be built in to the system. Above that, it connects to the house ductwork. The vertical rise here is only about a foot before it comes to a "T". I don't have enough room in this section to mount the unit, but I could mount it just below in the heavier, insulated section that is part of the unit. Would there be a problem mounting it there? Would the temperatures be too high?

You are fine putting it there.. Just cut back the insulation of where you are going to put the humidifier.

Where is the furnace at if you have insulation on it?

I'm sorry, maybe I wasn't as clear as I could have been. The ductwork coming off the furnace has a small layer of insulation inside. I discovered this when drilling a pilot hole just to make sure I wasn't in for any surprises.

Ok, now I under stand.

Yes, you can still cut the metal, and then cut the insulation to the size of the insulation.

Great, I'll let you know how it turns out.

Dan