A couple years ago I installed a furnace humidifier because the air in Colorado is extremely dry, especially when the cold winter air is heated to 68°F. When you heat cold dry air, the humidity level drops considerably. Our first solution was to run three small warm mist and cool mist humidifiers throughout the house which meant changing a lot of filters and re-filling with water. Even still, we would average about 11% humidity which meant every light switch, doorknob and button we touched produced a 1.21 gigawatt lightning bolt. That’s when I decided enough was enough and I needed something bigger. Either one of those big whole house humidifiers that looks like a small refrigerator and is a serious eye-sore or a furnace humidifier that is out of sight, out of mind. I chose the latter.
I decided upon an Auto Flo 97 furnace humidifier because it looked like it would adequately humidify my 2,600 sqft house. When and if you decide to purchase a whole house humidifier that attaches to your furnace, make sure it is sized properly for your house. Getting a bigger humidifier can create too much humidity which creates a whole different set of problems that are very annoying, such as water dripping from the windows. Getting a humidifier that’s too small may not make a worthwhile difference in the comfort level because it wouldn’t be able to put out enough humidity. Also, most modern furnaces have an electrical hook-up for a humidifier accessory, but reference your manual to make sure.
If you don’t have a accessory hook-up you can still install the humidifier, but you will need to do a little more work such as adding a transformer and wiring the humidifier in with the blower motor so the humidifier doesn’t spin all the time. This may also void any warranty you have on the furnace so its best to check with the manufacturer.
To install a furnace humidifier, you have to cut two hole in the duct work. One in the plenum and one in the cold air return as seen here. You will also need to tap into a cold water pipe for the water supply. Tapping into the cold water pipe was easy because they provided a little valve that clamps onto, and screws into the pipe. This was very easy and no tools were required. To cut holes in the sheet metal, you will need sheet metal clips. The humidifier manufacturer should provide a template to make the cutting easy with little to no measurements.
Since installing the Auto Flo 97, we have notice a huge difference in humidity and comfort level. Instead of averaging 11% humidity, we now average around 25%, but it did take about a week for the humidity levels to start increasing. This seems to be a perfect amount because we no longer get shocked when touching light switches, doorknobs or buttons on electrical equipment. The comfort level is so much nicer we really feel a difference between a friends house that doesn’t have one and our house. We also have installed a humidistat to control the amount of moisture entering the system. We don’t want too much because the moisture will start condensing on the cold windows.