Its a pretty generic relay. Its nothing fancy. I use it so that I can utilize the low speed fan windings on my furnace. I have my air handler configured to run every now and then via a separate control box, and this is the relay I use. It got a lot of daily use since I got it, and its still working. It can't be that bad.

great for using thermostats to control fans.

we installed this on our furnace and it failed during the night, we woke to a freezing house and had to call service. They found that the relay failed.

My house was built in the fifties and I'm converting it little by little to a smart home with substandard wiring. I have an old Williams milivolt wall heater that I just absolutely love but it just has the old style on off Mercury type of switch and converted it to a nest gen 2 in October. I needed to put a power supply and a relay to make this compatible with that heater and it works. There is an audible click and when the relay switches on but I've kind of gotten to like that because I know that might my heater is engaged .... great product

I used this in my heat only 2-wire system to add a "C" wire to power the Nest Thermostat.

Although the Nest worked without the "C" wire, it was temperamental, especially when the Nest called for heat often. As the Nest only pulls power from the two wires when furnace is NOT calling for heat, the Nest would be erratic if the heater was on often, and the Nest could not get enough power.

This little relay solved the problem. By wiring it in with the 24VAC transformer in the furnace, and sharing one of the leads with the "C" connection in the Nest, my Nest now always has power, even when furnace is calling for heat.

It has performed flawlessly all winter. No noticeable noise other than a very slight "click" when it energizes, but this happens at the same time the other furnace relay clicks, so it's barely noticeable.

Bottom line... if you need to add a "C" wire to a 2-wire heating system, this works like a charm!