ECM Motors and By-pass Humidifiers

I recently was asked the question, “Can I use a by-pass humidifier on a furnace with an ECM motor?”  Now, I had never seen anything to the contrary, so I figured the best source was to go to the ECM Motor manufacturer — Regal Beloit — and ask them the same question.

As we all know, moisture is one of the biggest problems when it comes to any electronics.  Since the ECM motor has the motor module on it that contains its electronics, this was a very good question.

Well, according to Regal Beloit, by-pass humidifiers CAN be used with ECM Motors.  HOWEVER – when you think about it ( it makes a lot of sense), the return duct with the by-pass humidifier attached to it should come into the furnace on the OPPOSITE side of the furnace from where the motor is mounted into  the blower housing.   This keeps the “humid air” out of the motor and its electronics.

This was one of those “ah ha!” moments.  More over, I learned something new from this question.  Then it got me thinking about all the times we hear about furnaces that have repeat ECM Motor failures.  How many of these have by-pass humidifiers and have the return on the furnace on the side the motor is mounted?

We always”assume” that most problems with ECM motors are “voltage related” and add “choke coils” to control the voltage better, but how many are simply because the humidifier is actually causing the problem?

So, it was a very good question and I’m glad it was asked.  Anytime I can learn something new is a great day.  I plan to add this tidbit to my furnace training.

Hopefully, when you install a furnace that  has an ECM motor in it and plan to use a by-pass humidifier, try to make sure that the motor is not directly exposed to the moisture or you could have repeat failures of  those motors and then ‘bad mouth”  the motor or manufacturer when it really is an application issue.

About yorkcentraltechtalk

I have been in the HVAC industry most of my life. I worked 25 years for contractors on anything from residential to large commercial boilers and power burners. For the past 23+ years I had been employed by York International UPG Division ( a division of Johnson Controls) as a Technical support/Service Manager but I am now retired. One of my goals has always been to "educate" dealers and contractors. The reason for starting this blog was to share some knowledge, thoughts, ideas, etc with anyone who takes the time to read it. The contents of this blog are my own opinions, thoughts, experiences and should not be construed as those of Johnson Controls York UPG in any way. I hope you find this a help. I always welcome comments and suggestions for postings and will do my best to address any thoughts, questions, or topics you may want to hear about. Thanks for taking the time to read my postings! Mike Bishop
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7 Responses to ECM Motors and By-pass Humidifiers

  1. Whit Perry says:

    You mentioned choke coils. Could you discuss them in a future blog or direct me to a previous blog if you’ve already discussed them.

  2. Since the ECM electronics are all sealed in epoxy they should be impervious to moisture. What is left is no different than a PSC. If those statements are true then PSC motors need the same protection that ECM motors receive.

    • Bruce — the electronics in the ecm module are “sealed” to a point. If you remember, all the instructions say that the plugs should always be pointed down and a drip loop put in the harnesses to keep moisture out.
      If you really think about it, , YES — the humidity from a bypass humidifier is getting into any motor that has the return on the same side. the only saving point with a psc motor is there are no “electronics”.
      The post was based on the info I received from regal Beloit. Here are the exact words they responded with:
      “Hi Mike, yes they can be used with bypass humidifiers and yes the return should be on the opposite side of the motor.
      Thank you,
      Christopher A. Mohalley
      Training Manager
      Regal Beloit America, Inc.

  3. oscar wells says:

    i see way to much mold when a By-pass Humidifiers is installed on a electric furnaces any suggestion for By-pass Humidifiers installation on electric furnaces

    • Oscar — I would suggest using some type of temperature compensating humidistat. Most humidisatats just look at indoor RH.. the Temperature compensating will look at indoor RH but also outdoor temp and decrease humidity as temps go down to maintan a set level. Most hoeowners “set it and forget it” and then get steam on the windows, etc. the temperature compensating humidisitat will automatically change the setting based on indoor RH and outdoor temp

  4. Snake says:

    So I guess the furnace control board would be okay since it would not be in the path of the return air stream? (boards that are mounted on or near the blower housing) What’s with the thing at the very bottom of the page?

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