Whole house humidifier installation advice

[stephen_smith]

Greetings all!

I live in southern New Mexico and the dry winters out here have me contemplating the installation of a whole house humidifer such as the Desert Spring Rotary Disc Furnace-Mount Humidifier.

I have an older PBKM-LD12N080C furnace manufactured circa 1994 that is installed in a small closet in the garage. This is an upflow furnace with a bottom return. Instead of having a conventional cold air return from the attic, indoor air is drawn into the blower from a central location in an adjacent room up through the wooden base/pedestal which supports the furnace.

Manual: (http://www.hamiltonhomeproducts.com/...KD-Install.pdf)







The installation instructions (http://www.desertspringproducts.com/...anual_R2_1.pdf) for the Desert Spring Rotar humidifier, and some other bypass humidifiers, call for mounting the humidifier on the cold air return ducting, though this old furnace wasn't installed with a cold air return. Given that the air is returned through the wooden base--along with the limited space in the furnace closet--I'm wondering if the humidifier can be mounted in another location?

BTW, there are two narrow, parallel ducts leading down from the upper left corner of the furnace closet which connect to nothing either in the furnace closet or attic. Any idea what this pair of slim ducts was intended for?





Any help would be appreciated!


Stephen

[Jay11J]

Welcome Stephen,

Yes, you are pretty tight in that closet, and can't really tell if you have room or not, but you could mount the humidifier on the supply duct above the furnace, and then cut a 6" hole into the floor for the bypass duct.

Another thing you could do is either by a fan powered unit, or Honeywell TrueSTEAM, and that will go on/into the supply duct above.

It looks like you don't have A/C on this furnace?

The two duct you are asking about is for make up air for the furnace's burner. When the burner is on, it needs fresh air for it to run, and the air is coming into those duct from up in the attic or outside. So, do not block those.

[stephen_smith]

Originally Posted by Jay11J

Welcome Stephen,
Another thing you could do is either by a fan powered unit, or Honeywell TrueSTEAM, and that will go on/into the supply duct above.

Thanks for the suggestion! I was looking into the TrueSteam, but it requires a floor drain, and none is present in the garage. I'm also concerned that the energy consumption needed to boil the water to create the steam will exceed any savings on water usage.

Because the bypass humidifiers seem to be impractical due to the lack of a cold air return, are there recommendations for pass through humidifiers, powered or not, (that do not require a floor drain) that could work in this scenario?

It looks like you don't have A/C on this furnace?

Yep, there's no AC installed. We have a roof mounted evaporative cooler which also has the benefit of humidifying the indoor air during the warmer months.

[Jay11J]

Yes, a floor drain is needed for the powered unit, and most bypass unit.

Is there a laundry room near by, or what's on the other side of the closet?