Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Will it work on a horizontially mounted interior unit ?
Document: Find a spot for the bypass (a 6" round duct) on the other duct and make a hole there. The unit mounts the the duct with several screws (self taping sheet metal screws make fast work) and two screws for the 6" duct coming off of it. Just a tip - if the unit can be mounted with the first section of duct attached then screw it on before mounting it. I had a little trouble getting a drill in there once it was mounted to the furnace.
I mounted the humidistat before the humidifier on the cold air return.The humidistat will work in automatic mode based on outside temperature. I found this a little conservative for my home. When in manual mode I can maintain over 40% humidity without a problem. I usually don't keep it this high but wanted to see if it could do it. I took the same humidity readings as prior and have a reading within 3% throughout the house.
I purchased this as an update from the 45 series but the unit sizes are different. Therefore I had to do some modification to my duct work to make it fit. Works pretty good, I can't complain...just not what I was expecting.
I used two adjustable elbows and a short section of flex duct to make the connection between the unit and the bypass.Now for the water. I did more research on this than I care to admit. Here's what I kept reading, if the furnace does not have long run cycles then run hot water to the humidifier. They explained it that if the furnace doesn't get hot for a long time then the humidifier will not work as efficient. So, with that logic I ran hot water to it.
Just make sure it is tight and secure. It should NOT easily slide if mounted well. The leak I experienced was at the actual compression connection of the tubing.I had to use the sheet metal shears when cutting parts of the rectangle behind the humidifier mostly because the cooling coil sitting behind this area had some coolant tubing that was too close to the area being cut. Had I used the jigsaw entirely, I would have damaged the cooling tubes.
My installer said it wouldn't work. I recommend showing pictguryour current setup to installer before buying this. Also A/C people I called had no experience or time&interest to do small job like this.
This humidifier is awesome! It works just like it should. I have read many reviews and some of them say that this thing does not work like it should, what I/we have found out is that most of these people must think that magic is real? in general this works like stated in the instructions, the humidity in my house 2500 sq ft ranch in Michigan bounces between  30~60% most all year.
I'm fairly handy as a homeowner, so I did the installation work myself. I followed the wiring diagrams provided, however, it would not work right (it was turning the A/C on). I hired a Professional contractor, who reviewed how I had it wired, and agreed it was wired correctly, per the book. After a while, we agreed it needed an isolation relay. He installed it, and it worked.
I've never installed a furnace humidifier before and could maybe half the installation time with newly garnered experience. I am realizing just how much I used to shudder at the air coming out of the vents -- I felt like I was dry rotting alive -- and now the house is so much more pleasant. The auto mode doesn't seem to work very efficiently for me, so I keep it on manual.
Year round according to my weather station. I have had to make some small adjustments to get my house acclimated to having a humidifier that actually works but in no time I have it under control and the humidifier has keep the humidity consistent % 35% right where I set it you must experiment a little because it all depends on things like where you live believe it or not because of altitude and things of that nature then make small adjustments from there it will work just like it says.
Answer: Yes it should. You can check out mounting instructions on the Aprilaire site.