6AZU2 Enclosed Fan Relay, SPNO, 24V

This relay works perfectly for the Nest thermostat and Aprilaire Whole-House Humidifier with the simple 24VAC water solenoid/valve. Nest will not provide any information on connecting the two systems, and will only direct you to a $$$ professional HVAC company. The Aprilaire representative was sympathetic and directed me to search the internet for a relay, and online HVAC or DYI forums. I added the wiring diagram that works for my system, as a picture for this relay, and included a HVAC forum link in the comment section of this review. This information probably does not suit all systems, but it relates to 90% of the systems in the Midwest. Using the wiring diagram as shown with the "H" or humidifier power tap on my Carrier furnace only turns on only when the heat cycle is running. So when the Nest sees a demand for humidity, it closes the new relay, starts the fan, but there's no power to the water solenoid until the heat kicks in. Consequently, the fan may continually run without providing humidification. This alternative does not replace the Aprilaire Humidistat with outdoor temperature monitoring, and automatic turn down for temperatures below 30 degrees, like the Aprilaire RP-58 Automatic Digital Humidifier Controls. These automatic humidity controls are far superior to the Nest for control winter humidity. The Nest requires you to monitor the outside temperature, house humidity, understand what adjustments are needed, and then use the Nest app to change the humidifier setting. Thanks Aprilaire for making reliable systems and having great customer service. After researching this problem, I wish I would have bought a less expensive WIFI thermostat and the RP-58 humidistat.

Edit: This is junk. I have problems just like others. It worked for a couple of weeks, but now I had to unhook my humidifier because it was stuck on. If you are buying this to use a whole house humidifier with a Nest thermostat, purchase a white-rodgers 90-290q relay instead. That's what I purchased to replace this one and it works great, and it is also 10 times quieter than this relay was. This one has a very loud click when engaging and disengaging.

Purchased for use with my nest thermostat and my dehumidifier. Works perfect for my application.

I have a HVAC system with a humidifier and had an issue with a Nest Thermostat that would over heat (i.e. Thermostat would be warm to the touch). I found the wiring diagram attached which basically shows that you need a relay switch with a powered humidifier, which is what I have. This unit was easy to install and worked perfectly!

Bought this to use with a nest thermostat to run a honeywell humidifier. Install was easy and it worked great for 3 months. This past month the relay stopped working. I understand defects happen but because of this I have to give it 1 star.

There's not much negative I can say about these. They're a standard commercial relay and they do exactly what they say they'll do. They're built solid, as you'd expect from this kind of component. They worked immediately upon hookup. If I needed these on a regular basis, I'd have no hesitation in buying these over and over again. I bought them so that I could have my Nest thermostat control my whole home humidifiers, and they worked perfectly for that purpose.

Just what I needed.

Worked fine for about 10 years then relay would stick on (closed) and not open or shut off until tapped. This would cause my Aprilaire humidifier, which this was hooked up to, to constantly run, wasting hot water.