Need to do the same in my house but in the opposite direction.
If my duct were that bare it would have a few inches of mold on it.
Humidity in the south is no joke.
Even now (in the "winter") I'm using a dehumidifier to keep the basement under 60%.
That being said, the last snow when it was single digits for a week, nosebleeds were no fun. Especially with the electric heat going 24/7.
Do you guys have a relay setup to keep the humidifiers from running when the main blower is off?
I would be worried about moisture building up in the duct otherwise.
I can still relate. The humidity and mold when I lived in HK was/is legendary.
First thing I did when I woke up every morning was empty the bedroom's stand-alone dehumidifier.
Then I moved back to the high and dry prairie.
Yes, to the relay question. In fact, one of the old relays was toast and had to be replaced in the process. The advantage to rotating drums is that the water pan fills up and then the float valve shuts off the water. Then the low-water sensor kicks in as needed to keep the pan full. The drum only rotates when the furnace is on.
The disadvantage to the drums is that there are more moving parts and more to go wrong.
The new humidifiers ditch the drums and are a gravity-fed trickle thingermajiggy, so basically no moving parts and thus less electricity consumed, BUT they are a total loss system. When the furnace is on, the water relay trips the water a tricklin' and there is unfortunately some water wastage.
It's so dry here, moisture still wouldn't build up in the duct; the water turns off when the furnace isn't blowing.
We have two furnaces (two-level house), so two humidifiers. My HVAC friend's house is one level and he has a furnace that is almost too small for the house so when it's really cold the furnace is almost always constantly on, and thus so is the humidifier and he has a stable humidity level. Due to the upstairs/downstairs split at mine, the humidity is always trying to balance itself out between the two floors.
At night the main-floor furnace is set to eco mode, during the day we turn down the furnace for the upper bedrooms — I bet my friend spends less on heating not because he has but one furnace, but because his furnace is mostly coasting, just maintaining a temperature; whereas ours are always transitioning.
Nonetheless, even though I have a powerful dual-furnace system, I also have a thick-furred dog and wife experiencing The Great Change, thus ensuring that I'm still always cold.
Too much blathering on about my furnaces...
Also on the workbench:
I've partially populated a PCB tonight. No pics, alas, as I'm missing a few values in caps and resistors.
