Aprilaire 50 Sensing Relay, 24-volt

Works great

I have installed two of the Honeywell HE-360 humidifiers in my home, and use this relay to trigger the system to run only when the heat is activated in my furnace. An humidistat also makes sure the humidifier only runs when humidification is needed, but this relay ensures that the powered humidifier runs only when the furnace blower is running in heat mode. If your thermostat doesn't control a humidifier directly (and most do not, unless you spend $200 or more for such a system,) you must have a means to control power to the humidifier.Without being too technical, most modern furnaces have blowers that operate at different speeds depending upon whether they are heating or cooling. This relay is placed on the wire that powers the furnace blower when in heat mode. The relay senses the power running through the wire, and closes a low voltage switch that drives a relay on the humidifier, turning it on. It's very simple to install if you follow the directions and have some electrical knowledge or skill.I've had one of these installed for 6 years, it works great with no problems.

Works perfectly

If you are not familiar with working on furnaces and working around / with electricity, then hire a licensed contractor. Safety first. Shut off the power to the furnace before starting this installation.I installed an Aprilaire 600M a few weeks back. My issue was that the unit would call for water at the panel when the furnace was off. This relay is the answer to the problem. Easy install as you locate the common wire going from the circuit board to the fan and run it between the metal clamp and the relay. The relay is wired between the valve on the humidifier and the low voltage transformer that comes with the humidifier. The relay is lightweight so there is no need to secure it to any surface. Problem solved and it only took around 20 minutes of my time.

This unit prevents the humidifier from running when the furnace blower is not running. when the humidifier is running without the blower running it just humidifies the air in the duct without circulating through the house and to the humistat wasting a lot of water.Now the humidifier only runs when the blower is running (and the humidity is too low). Unfornunately the orifice on the April air puts out a lot more water than what can be evaporated of the wick. Over half goes down the drain.