Answers to Your Humidifier Questions

Q. I have an Aprilaire Humidifier. The humidifier works only when I turn it all the way to the maximum setting on the humidistat. Does this mean the humidistat is blown?

A. Usually the humidistat is just a switch that closes on call for humidity; most are low voltage connections. It should be easy to find a replacement.

Q. I have a slop sink that’s about 10 feet away from my furnace. Would it be right to go for the Aprilaire 400 or can I simply run the drain line along the wall to the sink?

A. Sure, go for it - a drain is a drain. Pipe it in with a good fall to the sink.

Q. I'm looking at installing a whole house humidifier. I have a carrier furnace model 58sta1stx.What is the best type of humidifier to get? My house is 3,000 square feet. What does the term by-pass humidifier mean?

A. Installing a humidifier is a good DIY job. By bypass, they mean the humidifier is put on the cold air drop or duct and a small pipe is run over to the heat duct or plenum from it. This lets warm air pass over the water.

Q. I'll be replacing an ancient AprilAire A112 with an A700, and in an effort to avoid last minute trips to a supplier, I have a question for the experts. Is a "sail switch" a viable alternative to an A50? My current A112 has a manual humidistat and a sail switch, but no A50. The furnace has been replaced and I could probably use the humidifier terminals, but it seems a blower sensor is more flexible.

A. A sail switch just has too many reasons why it doesn’t work. Maybe dirt, or perhaps it is out a balance. So the humidifier works best if just on its own, not on the furnace board. That means do get a current sensing relay to use. Check out which one you need: either A50 for 24 volts, or the A51 for 120 volts. They work like an amp probe - just slip around the blower wires. Any time the blower is on, it will turn the humidifier on if the humidistat calls for it.

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