Installing a whole house humidifier

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nkwak
Posts: 650
Joined: Sat Nov 13, 2010 9:55 pm
Location: Pittsburgh PA suburbs

Re: Installing a whole house humidifier

Post by nkwak »

OK, I'm reconsidering the model. My house is 2,000 sq ft. The 600 series is overkill; it has a 4,000 sq ft capacity. The 500M's dimensions are 16 X 11 X 13 and but it needs clearance below for the drain line. Spot 2 isn't ideal because it's practically sitting on my hot water heater and the old humidistat is in the way (so it'll have to go) but it's also not going to drip on that electrical box and it's a more direct shot to the floor drain.
~ Neil
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Installing a whole house humidifier

Post by Diane Kauffmds »

Frank days that the capacity (square foot) rating, isn't hugely important. It'll run according to your humidistat setting, but only while your furnace is running. It cannot be too large, unlike an air conditioner. But, it can be too small. The rating is the maximum area that its capable of humidifying. Just make sure you don't go under a rating of 2000 sf.

The one problem we've encountered is that our 92% efficient furnace, installed in our well sealed house, doesn't run long or often enough to humidify the house to the setting on the humidifier. I frequently have winter humidity readings of less than 25%, even with the humidifier set at 45% or higher. Energy efficiency is a double edged sword. I have to run 2 humidifiers in the shop area to attempt to keep it at 45%.

All of the units have the same drain line location, so the clearance will be the same. Frank said to choose the unit based on the unit's physical size. Just don't go below a rating of 2000 sf.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
nkwak
Posts: 650
Joined: Sat Nov 13, 2010 9:55 pm
Location: Pittsburgh PA suburbs

Re: Installing a whole house humidifier

Post by nkwak »

Thanks once again to you and your husband, Diane. TBH the 600 would be a tight fit so I went ahead and ordered the 500M. It should be here in about 4 days.
~ Neil
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Installing a whole house humidifier

Post by Diane Kauffmds »

We're glad to help. You made a good choice.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
nkwak
Posts: 650
Joined: Sat Nov 13, 2010 9:55 pm
Location: Pittsburgh PA suburbs

Re: Installing a whole house humidifier

Post by nkwak »

OK, I have the unit physically installed but not wired up yet. The picture is cut off but I also installed the humidistat on the same face as the outlet, but not directly above it. I haven't removed the old humidistat but it's also no longer wired and I was going to take it out. The old humidifier was taken out when we had a new furnace put in but the wiring that powered it appears to have been wired into the new furnace (actually, it's 11 years old now; Carrier 58MCB100) but I'm not sure how it's connected.

Image

Image

Note the black and white wires that enter into and out of a box at the left of the following picture. I'm guessing the control board is sealed below.

Image

Here's what the control board should look like.
https://www.repairclinic.com/PartDetail ... B100-10116

The Aprilaire instructions say to wire the 24V line to the common connection of the blower motor.
~ Neil
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Installing a whole house humidifier

Post by Diane Kauffmds »

Okay Neil. The first thing Frank said was, nix the instructions. Don't hook the control to the fan. If you follow the instructions and someone puts the fan in the "on" position, your humidifier will run, causing the humidity to rise quickly. You want it to run when the heat comes on.

You will most likely need a length of thermostat wire. Just go to any big box store, and buy the thinnest single wire. Thermostat wire is 18 gauge. You can even use a lamp cord. You'll need enough to extend one of the wires from the humidifier to your furnace circuit board, and you'll need a wire that will run from the humidistat to the circuit board.

Yes, the control panel for your furnace is in the area that you indicated, sealed below in the photo. You will need to open the door on the front. There may or may not be screws. The circuit board may or may not be covered, but you need to gain access to the circuit board.

Wire this way:

The humidifier has 2 wires, one will go to the humidistat, and the other will go to the circuit board on the furnace. It does NOT matter which wire goes where.

Take one wire from the humidifier and hook it to one of the screws on the humidistat. Again, it does NOT matter which screw you use. You're going to hook a piece of 18 gauge, or thermostat wire, to the other screw and run it down to the circuit board on your furnace. Locate the screw on your furnace circuit board labeled as "c". Screw the wire from the humidistat to the "c" screw on the furnace circuitboard.


You will may need to lengthen the other wire on the Aprilair, so that it easily reaches the circuit board on your furnace. Use a length of the 18 gauge, or thermostat, wire to do this. Locate the screw on your furnace circuit board labeled as "w". Screw the wire from the Aprilair humidifier to the "w" screw on the furnace circuit board.

That's it. All done. Test everything by running the furnace. When the furnace runs (heat is actually running, not fan), the Aprilair humdifier should run in tandem.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
nkwak
Posts: 650
Joined: Sat Nov 13, 2010 9:55 pm
Location: Pittsburgh PA suburbs

Re: Installing a whole house humidifier

Post by nkwak »

Thank you and your husband, Diane.

Quite frankly, electricity and water together scare the crap out of me. You're helping me build my confidence. Before this I didn't even know how to take the front cover off the furnace. When I was in the Navy I got flagged on a surprise extension when I was caught doing light electrical work without my rubber gloves on. Aboard ship there's no such thing as a ground wire.

Looking at my control board I see that there's a HUM fitting. Also, what about the 24V transformer that came with the unit?

Also, I'm rethinking using a saddle valve on the hot water line right out of the hot water heater. We had an interruption of water pressure due to a water main break nearby and the saddle valve I'd installed on a cold water line to feed the ice maker on my refrigerator starting leaking badly this morning. Fortunately, I was able to rectify that by removing, resealing and tightening the valve but I don't want that to happen next to the furnace since I'll be drawing from hot water right off the water heater. I have a section of copper tubing and I'm thinking of picking up a compression T-fitting to do the job.

PS: my wife will kill me if I monkey with the water any more before Thanksgiving though and I'm supposed to be doing laundry and dishes in anticipation of having some particularly picky houseguests come for dinner. I'm trying my best to bite my tongue.
~ Neil
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Installing a whole house humidifier

Post by Diane Kauffmds »

Ignore the HUM and that 24v transformer; they're used for connecting the humidifier to the fan. Just do as outlined in my previous post. Frank said the saddle valve is a good idea. He also said that if you put the valve closer to the water heater, you'll get hot water sooner, and it will be away from the humidifier, so you won't have the threat of the valve spewing water on the furnace or electrical connections.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
nkwak
Posts: 650
Joined: Sat Nov 13, 2010 9:55 pm
Location: Pittsburgh PA suburbs

Re: Installing a whole house humidifier

Post by nkwak »

UPDATE: it’s all hooked up and doing stuff. It kicks off and on when the furnace does but I expect there will need to be some tweaks.
~ Neil
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Installing a whole house humidifier

Post by Diane Kauffmds »

If it's coming on with the furnace, and turning off when the furnace is off, then the wiring is right on the money. Congratulations, you did a good job. You'll just have to tweak your humidity setting based on your preference.

Good job Neil.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
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