This old house came with a humidifier which was probably original equipment. It's not clear how many years it has been since it worked, but I knew from day one that I would have to replace it.
- It was covered and caked in hard water deposits
- The internal water delivery pipe was three-quarters missing
- It hung off the side of the furnace on half its original screws
- All four edges had wide gaps, two sides big enough for a hand to fit into
- The gaps had long ago been covered with metal tape, but that had long since worn off and hung sadly, flapping in the draft
Initially this installation task seemed daunting, perhaps above my ability level as an amateur, but when I thought about it I realized that every step would be very simple.
- The old humidifier was much larger than the new one, so I had to first cover the difference with sheet metal. First I cut the whole sheet down to the size of the hole, then I cut a rectangle within it for the humidifier to mount in. I assembled those two pieces before attaching it to the furnace.
- I used a dremel tool with metal-cutting discs for all cuts in the sheet metal and, later, the metal ducting of the air intake vent. I cut carefully and used eight discs altogether, including breaking six of them.
- Worried that air would leak around the edges of the humidifier, I sealed the inside edges of the sheet-metal-and-humidifier assembly with metal tape.
- I drilled holes with a metal-drilling drill bit in an electric drill. Please note that drill bits designed for substances other than metal will not work, so do not waste your time trying to use the wrong bit. Seriously. Listen to me, it's a waste of your time.
- There were three holes in the side of the furnace where the old humidifier was attached and I re-used those, along with the original large metal screws, to hang the metal-sheet assembly onto the furnace.
- I correctly guessed that the hardest part would be hooking up the water. The old water line dangled oddly where the old humidifier had been, and slowly dripped into a bucket I put there. When I tried to unscrew it from the disembodied chunk of the old humidifier to which it was attached, water sprayed everywhere. Closing the valve on the tap line did not help. I ended up turning off the water to the house and draining the line, which I have to admit is what the directions said to do in the first place.
- The old humidifier did not have an air line attached to the air intake duct, and cutting the hole for this one was hard. Cutting a round(ish) hole with a dremel tool is challenging.
- Protip: do your best to bend the metal accordion-duct into exactly the shape you need before attempting to attach it on one end to the air intake duct and the other to the humidifier. If you attempt to bend it into shape while holding it in place, you will likely become frustrated and damage things.
- The directions said to mark the air intake fixture Summer when it is mostly closed off, and Winter when it is open, so I did that with a black marker.
- It is wired into the furnace, so when the furnace turns on this thing turns on. I tried it and it worked.
- When I was bending the accordion duct, I pressed it too hard and bent it a bit.
- I wrote Summer and Winter upside down on the side of the air intake fixture, and had to turn it around and use the other side to write it correctly.