Below I have a list of questions and answers to questions that potential customers or customers have asked me about Aprilaire humidifiers over the years. More questions and answers will be coming soon!

Please click here to return to our Aprilaire Humidifiers Page.

If you need to ask Aprilaire more questions.

 Aprilaire's Customer Support Number is: 1-800-334-6011

1. What is the difference in a power humidifier, Aprilaire 700 and a by-pass humidifier such as the 550, 600, & 400? Do you think a homeowner can do the installation?

Answer: Depending on the square footage of your home, and cost would determine which humidifier you choose. If your home is over 2,000 square feet I would definitely go with the 700. If you have a smaller home under 2,000 square feet I would probably go with the 550, 600 or 400 humidifiers.  My own personal opinion is that I like the power humidifier (700) over the by-pass humidifiers because with the bypass humidifier you are running humidified air across your filter, blower, heat exchanger and up through your furnace. The thought of having the moist air running up through your furnace just doesn't make sense to me, but people having be using them for years with excellent humidification results. Also, make sure you have enough room for the humidifier. You should have at least 16" between the furnace and a wall or obstruction to be able to install and service the humidifier. 16" is the minimum. 24" would be more preferable. The hole that you cut in the furnace duct work for the 700 is approximately 15" square. If you do not understand the concepts of high and low voltage electrical wiring, some sheet metal work and plumbing work, then I would probably leave it to a professional. The humidifiers with the computerized humidistat (700,600, 400) require 6 low voltage wiring connections and one high voltage 110 volt connection. If you have a friend that understands wiring and how to read a diagram then maybe they could help? The Aprilaire humidifiers can turn off and on by using an A50 current sensing relay.  If you have a newer furnace, with hook ups on the control board for humidifiers or electronic air cleaners, then you will not need the A50 relay. You can wire you humidifier to turn off and on using your furnace's control board. You can tell whether or not you need the relay by looking at the board or looking and reading the furnace's wiring schematic. The Aprilaire 700 humidifier has a transformer built in, to control the power fan relay and on off relay in the 700. The 550, 600, and 400 humidifiers come with a transformer that you can wire up. I always use the furnace's existing transformer to power the humidistat. I run wires up to the humidistat off the "R" and "C" terminals on the furnace's control board. If you decide to install the humidifier yourself, and you do not understand the wiring you can possibly burn the humidifier, humidistat, and your furnace controls up. This would void the humidifier's warranty. I would recommend hiring someone if you are not familiar with the wiring. I believe you will really like the humidifier once it is installed and working for a few days. No more dryness and static electricity. You will wake up feeling better!

2.  My humidifier runs all the time, even when the furnace is off. What could be the problem?

Being able to interface the Aprilaire humidifiers to turn off and on with the furnace blower or gas would depend on whether you have "HUM" (humidifier) hookups on your furnace's control board. Sometimes the "HUM" hookups are high voltage (110 volts) and sometimes they are low voltage. (24 volts). Please see the pictures of furnace control boards below. Sometimes if you have an older furnace you probably will not have any "HUM" hookup at all. If you do not have a "HUM" hookup you would need to purchase an A50 current sensing relay to make the humidifier cut off and on in conjunction with the furnace blower. The A50 acts like a light switch. When the furnace blower is on it senses the current and closes the connection between its two wires. When the blower goes off the A50 opens the circuit and turns your humidifier off. You can purchase an A50 on the following page for $27.00 plus shipping. The A50 is located near the bottom of this page: Click here: Aprilaire Humidifiers & Parts The A50 relay would be wired up in series with one brown wire that comes out of the bottom of the 700 humidifier. On the Aprilaire 600 & 400 humidifiers the A50 current sensing relay would make and break the circuit in the "H H" terminals of the 56 humidistat.  If you are installing an Aprilaire 700, and if you have a high voltage hook up on your furnace's control board, then you can use the high voltage hookup on the furnace's control board, wire up a receptacle (plug) attached to the side of your furnace so the Aprilaire 700 can plug in. I mount the 110 volt receptacle using self tapping sheet metal screws to the side of the furnace.  If you have a low voltage hookup on your control board...you can run this up to the "R & C" terminals of the Aprilaire 56 humidistat. It would be wired, Low voltage "HUM" on your control board up to "R" on the 56 humidistat. Low Voltage "C" (Com) on your control board up to "C" on the Aprilaire 56 humidistat. Polarity must be observed or it will burn up the humidistat and void the warranty. Also make sure these are low voltage, not 110 volts are it will burn the humidistat up. Please look at your furnace's wiring schematic or test with a meter. The low voltage hook up wires for the humidifier are usually located on the same row as your thermostat's low voltage wires. Once you get the humidifier wired using the A50 current sensing relay or through using your furnace's control board then you humidifier should turn off and on with your furnace's blower or gas valve.

Below is a picture of a Carrier Bryant board with a low voltage "HUM" connection on the board. You can tell this is a low voltage connection because the "HUM" hookup is on the same row as the low voltage thermostat wire hookups.

The board pictured below has a "HUM" hookup near the low voltage wires, but not on the same row. I would test the "HUM" terminal with a Volt meter to see if it is a 24 or 110 volt hookup.

Below is the wiring diagram for the Aprilaire 550:

Please click on the wiring thumbnails below for wiring diagrams for Aprilaire's 700 & 600 Humidifiers. The Aprilaire 400 would be wire the same as the Aprilaire 600 humidifier.  Please click your browser's "<" button to return to our site after viewing the thumbnail. Thanks! We would love to have your business!

700 Wiring Thumbnail       600 Wiring Thumbnail

More questions and answers coming soon. This page started: December 4, 2004.

Please click here to return to our Aprilaire Humidifiers Page.

3. Is it normal for quiet a bit of water to be running out of my 550, 600, 700 Aprilaire humidifier?

Yes, It is normal for a small stream of water to run out of the bottom, through the drain tube in the humidifier. This water flow should stop shortly after the humidifier goes off. If the water continues to run more than 5 minutes, you have a not wired the humidifier properly or you have a bad 4040 solenoid valve. Turn the furnace power off with the switch on the side.  If the water stops flowing the humidifier is not wired properly. Recheck the wiring diagram and wire properly. Please see above wiring diagrams.

4. What tools and supplies might I need to install a humidifier?

I mount many of the humidifiers on the side of the cooling coil all the time when I was doing installs. You want to make sure that you are on the sides of the coil and not on the ends. If you install the humidifier on the ends of the coil then it will restrict air flow to the humidifier. I always traced around the template making sure the template is level. You want to make sure your template is positioned high enough where you aren't cutting into the drain pain of the coil. Many times I take one end of the cased coil off, or move the coil cover back away enough so I can see inside the coil. I have seen so many coils that I know pretty much where to cut and not to cut. I would suggest starting as high as possible on where you drew the cut out with the template. Since the coils are pointed away near the top it is unlikely you would hit the coil if you start drilling near the top. I drill a hole large, sometimes with a metal cutting hole saw or large drill bit (do not drill deep just enough to go through the metal) big enough to get my sheet metal shears started then cut a small opening so I can see inside the cased coil, so you can see where the coil is positioned. You can always move the template up if you are not in a good position for cutting. Best of luck!

Steve.

 

6. I received my Aprilaire humidifier and it looks like the water panel has been used? I hope you are not selling me a used product?

Hi!

Thanks for your business! Everything that we sell is brand new unless I have it listed on our

Click here: Bonus Buys! page.  The Bonus Buys Page has merchandise that has been returned, but still brand new.

The Aprilaire humidifier water panels come with a coating on them to help hold the water to the water panel so you will get better evaporation of the water. You are not the first one to ask this question. Yes, they do look used, but this is the way they come from the factory. If you would like to call Aprilaire Customer support at 1-800-334-6011 and ask them about this then you may. We sell lots of the Aprilaire water panels and all of them have this coating. I hope you have a nice day! I also hope that you and your family have a Happy, Healthful and Prosperous 2005! God bless you and your family.

Sincerely, Steve Arnold, www.arnoldservice.com

 7.  I just installed my Aprilaire 700, and it is leaking water out of the bottom. What could be the problem?

Hi!

Sorry that you are having problems with the humidifier leaking. Problems that I have seen that cause humidifiers not to drain properly or leak are:

1. Out of plumb or not level. Please take the cover that contains the fan off and check to see if you are level and plumb. Please see picture below for part identification.

2. While you have the cover off, pull the scale control insert part 4236 out and inspect it for cracks in the plastic. Separate the distribution tray from the scale control insert and look to make sure the colored spot on the water panel is facing up.

3. Assemble back making sure the drain hole in the bottom of the scale control lines up with the hole in the body of the humidifier. Make sure feed tube and nozzle are in the right position attached to the distribution tray.

There is no reason why the humidifier should leak if all these guide lines are followed. Best of luck in finding the problem. I hope you have a nice day!

Steve Arnold, www.arnoldservice.com

 

8. My Aprilaire 700 humidifier will not turn on. Water will not run or the power fan will not turn on. What could be the problem?

Hi!

Thanks for your continued interest and support in our web site! If you can disconnect the wires from the humidistat that go to the humidifier (wires that go to the two brown wires that come out of the bottom of the humidifier) then plug the humidifier into a 110 volt outlet. Tie the two brown wires together that come out of the bottom of the humidifier together. The humidifier should come on and the water should flow. If it does come on then you probably have a 56 humidistat problem or outdoor sensor problem. If the humidifier doesn't come on then you probably have a humidifier control board problem. Please make sure you are getting 24 volts to the humidistat on the R & C terminals by checking with a meter. Best of luck in finding the problem.

Sincerely, Steve Arnold, www.arnoldservice.com
 

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            Louisville, KY. 40291