Humidifiers and Dehumidifiers - Mount on SIDE of plenum?

I've got an old bypass humidifier (General 1099) that isn't doing the job - I think it's a bad mounting job which isn't keeping the water trough properly leveled, so the water isn't infiltrating the water pad properly. Regardless, I'm at around 20% humidity with gallons of water down the drain every day. It's mounted on the return plenum (by way of a widening adapter so it fits) and the output is routed straight up into a trunk line. It's completely backwards from the bypass installation manuals' recommendations.

So we're looking to remove the old one, patch up all the holes, and get a powered unit like the Honeywell HE360. They like to be mounted on the other side, above the furnace. Problem is, the gas vent from the furnace is blocking the flat plenum area.

Can I simply mount the humidifier on the side of the furnace plenum? 90 degrees to the right from where the manual states? Does that make sense?

In my mind, air is filling that space completely, so it shouldn't matter which wall of the plenum I mount it on.

I've got an old bypass humidifier (General 1099)
I looked that model up, it's a valid current model.

It's mounted on the return plenum (by way of a widening adapter so it fits) and the output is routed straight up into a trunk line. It's completely backwards from the bypass installation manuals' recommendations.
A bypass unit can be mounted on either return or supply side.. Most installer prefer them on return due to lack of space on most supply side, and also less risk of water damage if something did go wrong.

Do you have a photo of your set up?


Can I simply mount the humidifier on the side of the furnace plenum? 90 degrees to the right from where the manual states? Does that make sense?
You could do that, do you have A/C? The A-Coil may be in the way.. (depends on how it's installed)

Thanks for the assistance - my setup is just like yours that I saw in another thread. I'm beginning to wonder if the problem is simply the trough and the pad I am using (bought cheap online)... For $150 I could get a new unit (and a minor upgrade from 1099 to 1099LHS), use the same plenum opening and just replumb the water and electric, shouldn't be rocket science. It'll give me a chance to firm up the entire installation and seal up the air gaps created during the original humidifier installation (as well as the rest of my HVAC system) with HVAC caulk and foil tape....

I found the 1099 LHS online for $165 shipped. Think I could do better than that?

I think you can do better.

But not sure if there something on the GeneralAire that you like vs the Honeywell?

I'm not seeing a Honeywell that can do as many sq ft and has the bypass on the right side like my General does... I'm up for buying any humidifier that's reasonably priced and easy to retrofit into my system. Here's a pic of the setup:

http://dvrcade.com/HVAC.jpg

How many sq ft is your home?

Is the opening size bigger than the return itself? (It seems to be. where mine was on the money)

Honeywell can be left or right side set up.

look into aprilair 700 model, it is a none bypass system that you would mount on side of supply duct. Also if you can hook up hot water to it, you would get much better effect. And it does not mater which side of duct you install it on. Supply duct is one above furnace and return duct is where your filter is.

look into aprilair 700 model, it is a none bypass system that you would mount on side of supply duct. Also if you can hook up hot water to it, you would get much better effect. And it does not mater which side of duct you install it on. Supply duct is one above furnace and return duct is where your filter is.Aprilair 700 model is about $250 if you are a contractor, I dont know what you can buy them online for. Hope this is helpful

How many sq ft is your home?

Is the opening size bigger than the return itself? (It seems to be. where mine was on the money)

Honeywell can be left or right side set up.

3000 sq ft... I wouldn't call it extremely tight but it's only eleven years old.

Yep - there is an aluminum adapter there that allows the larger plenum opening of the humidifier. Adds a few inches.

The Honeywell HE260 is rated for 4,000 sq ft.

Can be found at Home Center.

UPDATE!
I've broken down and bought an Aprilaire 700 with the powered fan so I don't need to worry about the bypass line. But it wouldn't be able to fit anywhere but the back of the supply plenum.

You could do that, do you have A/C? The A-Coil may be in the way.. (depends on how it's installed)

How do I determine where the A/C coils are?

Here's my HVAC system. I am planning on installing the humidifier on the back of the supply duct, above the A/C connections.

FRONT:
http://img220.imageshack.us/img220/7185/fronto.jpg

SIDE:
http://img21.imageshack.us/img21/489/sidefha.jpg

BACK:
http://img4.imageshack.us/img4/489/backlwz.jpg
http://img520.imageshack.us/img520/1171/closeupi.jpg

You may have to cut a small hole up higher on the back. The A/C line hook up is in back of the furnace (Copper/black lines).

Then look into the hole to see how far up the coil goes.

The flex gas line caught my eyes... I can't tell if that flex is going all the way into the cabinet or not? If it is, it should be removed and replaced with black pipe.

So it has to be a cut-and-see sort of proposition? I guess that's not a big deal. How far above those A/C lines would you suggest the first hole be? I've never seen the inside of this end of an HVAC system so I don't know what to expect in there!

Don't worry about the gas line on the side - it attaches to a fitting right at the edge of the furnace cabinet.

I'd make the first cut about 3/4 way up.

you'll see something like this inside.

http://img14.imageshack.us/img14/8721/acoilbare.jpg

Thanks! I did my reconnassiance cut and it worked out perfectly - I was a couple inches above the top of the coils and used that line as the bottom of my install cut.

It's up and mounted, just need to get it wired. So far I kept the GeneralAire humidistat and wiring and just moved the two leads to the Aprilaire, but I don't think it's working right. (The water valve ain't opening and it's REALLY hot.)

It don't sounds like you got low voltage going to the valve...

Where is the power coming from?