Installing a whole house humidifier

One of the last projects I had on my list for this year was installing a whole house humidifier. With our heat being forced air, it gets very dry in the winter time. This gets just plain uncomfortable with the static electricity and dry skin (I've never had allergy issues in the winter before - last year I did. The air was so dry my skin required an antihistamine to keep from being red and itchy).

Typically, I've used a single room standalone humidifier. They generally come in two types - cool and warm mist. Cool mist humidifiers simply blow air over a pad that is soaked with water, while warm mist humidifiers essentially boil the water into the air. I initially started with a cool mist one, but it was a pain to keep operating because it depended on vacuum pressure to draw water up to the top of the unit where it would pour over the pad. Half the time, the vacuum was insufficient - so it constantly required meddling.

Then I got a warm mist humidifier. Much easier to get going, but over time the crud builds up on the heating element and just gets nasty.

Both suffer from requiring regular refills. Doesn't sound like a big deal - but when you have to refill the damn thing 2 times e-v-e-r-y-d-a-y, its a pain in the butt. Of course, larger capacity humidifiers are available, but they take up more floor space - something we dont have.

In some ways, I'm a lazy person. I dont mind doing some grunt work or putting forth effort - but I'm usually looking for a way to do something more efficiently. So when I heard about the concept of a whole house humidifier, one that attaches to your duct system and has its own endless water supply, I said "WANT!".

So this past weekend, I went to Lowe's and picked one up for about $80. The design is pretty simple - you just have to muster up the gumption to start cutting holes into your HVAC ductwork and do some plumbing work. This can be somewhat intimidating - HVAC systems aren't cheap, and a screw up and be costly to fix.

The first step was to get water to the unit. The humidifier kit comes with a saddle valve - which is intended to wrap around an existing 1/2" copper tube that supplies water to some other fixture, and pierce a small hole through the copper tube to draw off water. These are commonly used for ice makers and other relatively small water volume uses.

Last year when I was installing a utility sink in the basement, I anticipated needing a water source for a whole house humidifier. So I ended up leaving myself with a T in the cold water supply that I capped off. This allowed me to avoid the saddle valve solution, which I was glad about. For one thing, the person at Lowe's informed me that their use is not up to MA plumbing code anymore, and for another - I just anticipated the possibility of leaks. Furthermore, when talking with a neighbor about using a saddle valve, he relayed his experience with using one, where the minerals in the water end up gumming up the tiny hole, reducing flow to a trickle.

So, next was to clean off the end of the copper tube, solder a valve in place, and run a length of 1/4 tube to where it would be needed. The valve used also reduced the 1/2" source to 1/4" compression-style fitting, eliminating the need for a reducer and an adapter.

Cleaned tube end

Valve soldered in place

Running tube

The next step was to cut a hole in the hot air side of the ductwork. This is done to draw hot air from the furnace and route it to the humidifier. The fitting for the flexible duct to be used is 6" in diameter. I started by using a borrowed pair of tin snips. Knowing how I was likely to make an ugly edge, I opted to go a bit shy of the 6" diamter - I'd rather have an ugly edge that is hidden because the diameter is too small, rather then make a situation where part of the hole diameter extends beyond 6" requiring some sort of patch. The hole would be cut in the foil-insulated portion of the duct, to avoid interference with A/C equipment located directly above blue furnace unit.

Hole in duct with fitting

Next a cutout would need to be made on the return air side, so the humidifier could be mounted. I started off with using the tin snips again - but after about 20 minutes of messing around with wierd angles, ugly cuts and warped sheet metal, I decided I either suck at using them, or there had to be a better way. I did a good search to try and learn some tricks of the trade. In the end, I found that I could use a dremel tool with a cutoff wheel, and do the job much more safely, easily, cleanly and quickly then monkeying around with the tin snips. It used a lot of cutting wheels, but at about $5 for 20 of them (each cutting wheel got me about 3-5 inches of cut in this particular sheet metal), it was worth it.

Cutout for humidifer

Mounted humidifier
Once mounted, all the hard work was done. The water could be connected, and evaporator pad installed and the cover put in place, and the appropriate wiring could be done.

All major pieces in place
Up to this point - everything had gone real well. No leaks on the water side, I had successfully navigated around the mine field of unknown A/C equipment, and had warm air flow from the hot side to the cold side.

The last step was to install an electronic controller - basically an item that senses temperature, and controls the valve that allows water to saturate the evap pad in the humidifier. This electronic controller required 3 holes - two for mounting (3/32" inch), and one for exposure to the hot air (3/8").

This is where things got ugly, quick.

The little voice in my head told me that I should really install the controller near the draw-off for the hot air - no A/C equipment was there, and it would be completely safe. However, the other voice in my head said 'that'll add a little bit of extra work, and c'mon - what are the chances you'll screw something up. I mean - how bad can it really end up getting?'

To make a long story and explanation short, lets just say that the drill bit, once it got through the sheet metal, grabbed onto a burr and continued in, nicking a paper thin copper tube on the A/C evaporator coil, and putting a hole into it. Immediately, I heard a hissing sound, and said 'oh.... shit!'. By the next morning, the entire charge of refrigerant in the system was gone.

At least it wasn't gas for the furnace. And at least it is not the cooling season. The ongoing saga of the repair situation on that is another story. But the main point is that I should have listened to the voice in my head, and listened to its caution. Not doing so has resulted in me needing to get the system charged up again (probably next spring), something that cannot be done without proper equipment, and will likely cost at least $250.

As long as the humidifier works in general, it'll still be totally worth it.