So Sunday I decided to tackle a long-standing, but low priority, repair: replacing our whole-house humidifier. It worked for the first two winters or so we had the house, but at some point I think the solenoid burned out and it was going to cost a lot to replace that and I just never got around to pursuing it. We've been using a small steam humidifier and Celeste has a Cool Mist one, but it'd be nice to not have to clean those every couple of days.
That morning, I was at Home Depot when it opened. I thought it opened at 7:00 a.m., so when I ran out at 7:30 a.m. to get a paper, I figured I'd flip by there to return some unused brass weather-stripping from another project. But it didn't open until 8:00 a.m., so I read a bit in the car and waited. After returning the weather-stripping, I went looking for some felt weather-stripping (the kitchen door has an annoying draft that the brass stuff wouldn't work for because of the locks, but some of the felt stuff has at least tamed the draft where it can't eliminate it) and for some reason decided to look at the whole-house humidifiers.
I didn't buy any humidification equipment, but I did go home to see what the cost of a new system vs. a solenoid repair would be. On its face, it was about $179 for a new one vs. $110 for a solenoid, so I decided to start a project. (I think it was the solenoid that was out, but I'd rather spend more for a complete system that should fix things instead of spending $70 less and have it turn out to not have been the problem.)
After running back out to Home Depot and then to Lowe's to compare all the available models, I found that only one was in the stores that would replace the current setup — a Honeywell HE360A. Its dimensions were a little off from the old unit (a predecessor to the Carrier SFP), but the physical installation of the unit wasn't that big of a deal.
The old plumbing fittings wouldn't work, so I had to run a new line from the hot water heater to the humidifier. Both the old and new systems used saddle taps to connect the line, so there was a bit of a mess in getting the old line unconnected and to line up the new tap with the old hole. I ran into one or two problems with the supplied compression connectors (in the end, I ran back out and got an icemaker connection kit, which gave me copper tubing for the line instead of plastic, and an extra compression nut), but I think the plumbing is all solid now. (I opened the tap this morning and a little drip of water came out at each fitting, but a little extra twist with a wrench seems to have fixed that. I don't want to leave the pipe pressurized all the time until I have everything working.)
Now the bit that's left undone is the electrical. I think I've figured out how the old humidistat was wired in, but the new one is a little different. Hopefully, I'll get it figured out tonight without too much trouble, but until I do, I guess I still need to refill the other humidifiers.
[ASIDE: Coming from South Louisiana, I still find the idea of needing to add humidity to the air nothing short of bizarre, but when we were at my parents' for Christmas, it was obvious how bone-dry the cold air was when it got cold and the heat was running so much.]
[UPDATE: I talked about this with a coworker this morning and walked him through how I thought I should wire things vs. what was on the schematics and (surprisingly unhelpful) installation instructions, and think I know what I need to do. He also loaned me a voltmeter (I melted mine a few years ago when I was replacing the fan in what's now the nursery with a light and needed to know which wire wasn't needed now that the fan was no longer there — I had it on the wrong setting and tried to change it while it was still connected to the wires; when I say "I melted it," I mean that all too literally) and I checked out things as Evelin adjusted the thermostat on/off.
The two wires that ran into the old humidistat seem to be connected to a relay so that when the furnace is on/off it will tell the humidifier to click on/off. When the furnace was on, the voltmeter'd read 24 volts (or so) and it would read 0 volts (or so) when the furnace was off.
So, I think all I need to do is run one of those wires to the humidifier, one to the humidistat, and then complete the circuit by connecting the humidistat to the humidifier. (I also have to cut a hole in the cool-air return duct to mount the humidistat, but I'm more worried about the wiring than that.)
Someone please leave me a comment if this sounds like I'm going to either kill myself or burn down the house. I don't know if I'm going to get to this until the weekend.]