Review on Aprilaire - 600MZ 600M Whole Home Humidifier, High Output Manual Furnace Humidifier for Large Houses up to 4,000 Sq. Ft. by Jennifer Stevenson

This is an amazing humidifier. We have 2400 square meters. ft and it helps well with the problems we had this winter: bumps and itching. There are many reviews on here saying how good it is, but I wanted to talk a bit about the wiring because there are so many diagrams on how to hook this up to the Nest and none of them match ours. needs. I'd like to give a glimpse to people who might need the same thing, namely a fully automatic Nest humidifier (3rd gen) that works whether the heater is on or not. Our house is only a few years old and the stove is quite efficient so the heating cycle is not long enough for the humidifier to bring the relative humidity in our house to the desired level. I ended up buying a relay that many of these circuits have and I didn't even need it. I'm not sure what the purpose of the relay is, but as you can see from the attached picture all the wiring in our system was done on the 24VAC terminals. This eliminates the need for a transformer, relay and hygrostat. This connection method allows Nest to fully control the humidifier. When Nest requests humidity, it sends 24VAC to the wire*, so if it is connected to the humidifier's solenoid valve and the common wire is connected to the other, the circuit is completed when needed. This connection also requires 6 wires to the outlet, so I routed the 18/7 wire by connecting it to the existing 18/5 wire and running it through the wall into the basement. The next step depends on your needs. If (and only if) you have hot water to a humidifier and the water heater is near the stove, you can set the 'Pro' setting on the thermostat to 'hum'. Only" and set the fan to Activate . Otherwise you need to run "Hum + Heat". Without hot water, you're just wasting a lot of cold water.