Product review (5 stars): Humidifier installation with Aprilair #50 current sensing relay
I used this Aprilair #50 current sensing relay to complete my installation of a Honeywell HE220A Whole House Bypass Humidifier. My installation was on a 20 year old furnace that does not have accessory terminals to control the humidifier. I followed the instructions supplied with the Aprilair relay to wire the 24VAC transformer, current sensing relay, humidstat, solenoid water valve circuit and the humidifier functions perfectly.

A basic understanding of electrical circuitry is necessary to install this relay. The relay is installed inside the furnace. I recommend professional installation to those without electrical wiring experience and who may not understand how to interpret the electrical schematic diagram supplied with their furnace.

This Aprilair #50 current sensing relay was exactly what I needed to complete my humidifier installation and I would recommend it to anyone that needs to install a humidifier on an older furnace that does not have accessory terminals.