How to Install an Aprilaire Whole-House Humidifier and More

Updated on January 11, 2018
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Dan has been in the HVAC industry for 22 years with experience ranging from installation and service to sales and distribution.

Introduction to Home Humidification

Adding a whole-house humidifier to your heating and air conditioning system is something you can do yourself to improve your air quality and comfort.

These easy-to-follow, step-by-step instructions and photos will show you all you need to know to install, operate, maintain and understand your furnace humidifier using an Aprilaire 600M unit as an example.

Table of Contents

  • Thinking About Buying a Whole-House Humidifier?
  • Benefits of Humidifiers
  • What You Need for Installation (Materials/Tools With Photos)
  • Where to Install a Humidifier
  • 12-Step Humidifier Installation Guide (With Photos)
  • Setting and Controlling Your Humidity Level
  • Basic Humidifier Maintenance and Parts
  • Conclusion

Thinking About Buying A Whole-House Humidifier?

The cost of installing or having a heating and cooling professional install a humidifier for you is really rather reasonable. If you're doing it yourself, you can expect to spend around $250 for the unit and necessary materials to install it. Even if you have to purchase a tool or two, you'd likely get out of the HVAC system upgrade for around $300 since you likely have most of the tools you need. If you have an HVAC contractor perform the installation for you, the cost will still be "earthly" and in the neighborhood of $400-$500.

Besides cutting down on your use of moisturizers and boiling pots of water on the stove, here is a list of benefits a whole house humidifier will provide to help pay for itself.

Benefits of Humidifiers

Health
Comfort
Value
Significantly reduces the amount of airborne dust in the home, thus reducing the suffering of those with allergies.
Lowers or even eliminates static electricity.
Save on energy bills—your furnace works harder to heat dry air.
Deters the spread of viruses that thrive in drier environments.
Reduces snoring
Wood floors and cabinets will maintain their appearance and last longer.
Prevents skin from drying and itching and lips from chapping
Helps keep house plants healthy—looking at dying plants doesn't conduce a feeling of comfort.
Increases home value—humidifiers are rather inexpensive but add value to your HVAC system, thus your home. In this way, they will more than pay for themselves.
The benefits far outweigh the cost!

What You Need for Installation

Now that we've decided adding a humidifier is a good and affordable idea, let's get started with installing a unit ourselves using a rather basic Aprilaire humidifier as an example. If you're going to hire a heating and cooling service provider for your install, perhaps you'll want to skip down to the maintenance and humidity control sections of this page.

Materials

  • Aprilaire Humidifier Kit (recommended) – Confirm the model is sized properly for your home.

Each kit comes with:

  • Unit with filter/panel and built-in damper
  • Transformer (110v/24v)
  • Saddle valve (to tap into existing hot water piping)
  • Humidistat (humidity control)
  • Installation template (for fitting the unit and humidistat)

This humidifier kit gets you started but you'll still need a couple items to go with it.
This humidifier kit gets you started but you'll still need a couple items to go with it. | Source
  • 3/4" PVC pipe – 10' should be sufficient if you have an A/C or furnace drain you can tap into.)
  • 3/4" PVC fittings – 1-tee, 4-90o elbows, 2-45o elbows, and 1-coupling should do, in most cases.
  • PVC cement – Very little is required and can be substituted with a waterproof silicone.
  • Small wire nuts – Small and usually blue. Six would be the most you'll use
  • 2 spade terminal connectors – These are usually small and blue.
  • 1" sheet metal screws – 6-10 should be fine.
  • 1/2" sheet metal screws – 10 or so should do.
  • 18/2 thermostat wire – This is low voltage wire (24V).
  • Foil or duct tape – Again, very little is needed.
  • 1/4" copper tubing – The required length will be the distance from the humidifier to the nearest hot water line.
  • 18/2 thermostat wire –This is low voltage wire (24V).
  • 6" round warm air pipe – You'll need a 5' pipe.
  • 1–6" take off – A 6" start collar and elbow could be used instead.
  • 6" adjustable elbows – Depending on your set up, you'll need no more than three.

Click thumbnail to view full-size
PVC pipe and fittings, wire nuts, spade terminals, screws, wire ties, and thermostat wire.A 6" warm air pipe and fittings—the take off is on the left, the elbow on the right, and the pipe at the back.A small tin of PVC cement/glueRolls of foil tape. Duct tape can be used, but this tape has taken over the HVAC industry. It is easily torn, but makes a better, longer-lasting seal.A coil of 1/4" copper tubing.
PVC pipe and fittings, wire nuts, spade terminals, screws, wire ties, and thermostat wire.
PVC pipe and fittings, wire nuts, spade terminals, screws, wire ties, and thermostat wire. | Source
A 6" warm air pipe and fittings—the take off is on the left, the elbow on the right, and the pipe at the back.
A 6" warm air pipe and fittings—the take off is on the left, the elbow on the right, and the pipe at the back. | Source
A small tin of PVC cement/glue
A small tin of PVC cement/glue | Source
Rolls of foil tape. Duct tape can be used, but this tape has taken over the HVAC industry. It is easily torn, but makes a better, longer-lasting seal.
Rolls of foil tape. Duct tape can be used, but this tape has taken over the HVAC industry. It is easily torn, but makes a better, longer-lasting seal. | Source
A coil of 1/4" copper tubing.
A coil of 1/4" copper tubing. | Source

Note: You may only need some of these, depending on the humidifier you're installing. You may find that you already have tools that can be used as substitutes for some of these HVAC specialty tools. Before you buy any of these items, perhaps you should assess your installation compared to this example.

  • Tape measure
  • Marker
  • Hammer
  • Flathead and Philip's screwdriver
  • Cordless (battery-powered) drill and 1/4" hex driver
  • Tin snips
  • Pliers – You will want two pairs of standard pliers or channel locks.
  • Torpedo level
  • Tubing cutter
  • Awl
  • Crimping tool

Click thumbnail to view full-size
Tape measure and markerHammer ImagePhillips head and flathead screwdrivers.Cordless drill. A 1/4" hex driver is needed to install sheet metal screws.Tin snips.Pliers. The center pair of pliers or the ones on the far right (channel locks) are what you need.Torpedo level—used to check that you're installing parts in the correct (most stable) orientations.Pipe cutters. The pair at the top are ideal. However, you can use a hacksaw or something similar to cut your PVC. The bottom cutter is for cutting your copper tubing.Awl. A scratch awl can be handy, depending on how you run your wiring.Sheet metal crimping tool. These will be handy if you need to cut and crimp your warm air pipe. You may not need to and can use needle nose pliers to create similar results.
Tape measure and marker
Tape measure and marker | Source
Hammer Image
Hammer Image | Source
Phillips head and flathead screwdrivers.
Phillips head and flathead screwdrivers. | Source
Cordless drill. A 1/4" hex driver is needed to install sheet metal screws.
Cordless drill. A 1/4" hex driver is needed to install sheet metal screws. | Source
Tin snips.
Tin snips. | Source
Pliers. The center pair of pliers or the ones on the far right (channel locks) are what you need.
Pliers. The center pair of pliers or the ones on the far right (channel locks) are what you need. | Source
Torpedo level—used to check that you're installing parts in the correct (most stable) orientations.
Torpedo level—used to check that you're installing parts in the correct (most stable) orientations. | Source
Pipe cutters. The pair at the top are ideal. However, you can use a hacksaw or something similar to cut your PVC. The bottom cutter is for cutting your copper tubing.
Pipe cutters. The pair at the top are ideal. However, you can use a hacksaw or something similar to cut your PVC. The bottom cutter is for cutting your copper tubing. | Source
Awl. A scratch awl can be handy, depending on how you run your wiring.
Awl. A scratch awl can be handy, depending on how you run your wiring. | Source
Sheet metal crimping tool. These will be handy if you need to cut and crimp your warm air pipe. You may not need to and can use needle nose pliers to create similar results.
Sheet metal crimping tool. These will be handy if you need to cut and crimp your warm air pipe. You may not need to and can use needle nose pliers to create similar results. | Source

Where to Install a Humidifier

Before we start cutting holes into our ductwork, we need to decide where we're going to install our humidifier. Your options may be limited by your existing heating and cooling system's set up. Again, I suggest you follow this example installation to the end to have a good understanding of what you will be doing and then make your decision.

Here are a few things to keep in mind—I've applied them to this home humidifier install.

  • Mount the unit on the return air duct whenever possible. You can mount to the supply side, but the system works much better on the return side and poses less of a threat to your furnace, should there ever be a malfunction involving water and electrical components.
  • Make sure there is enough room above the unit to mount your humidistat. It's suggested to be at least 6" above the unit.
  • Try to make the bypass connection as short and straight as possible.
  • Aprilaire units are able to be flipped around so that the bypass can be on either side.
  • Be sure you have room to remove the unit's cover, water pad/panel, and other parts for easy maintenance and repair in the future.
  • Visualize your drain path to be sure you'll be able to maintain a downward slope towards its destination. This ensures proper drainage and prevents stagnant water from building up in the line. Again, the shorter, the better.

Without further delay, let's start installing our humidifier!

Location is important. This is a very easy set-up ,and clearly, I will mount the unit to the return air on the right and bypass to the back of the plenum.
Location is important. This is a very easy set-up ,and clearly, I will mount the unit to the return air on the right and bypass to the back of the plenum. | Source

12-Step Humidifier Installation Guide (With Photos)

A picture is worth a thousand words, so why don't I keep this as simple as possible? Below, I've listed the steps for my Aprilaire 600M installation example, but you don't lose anything to your imagination, I've provided pictures to go along with these steps. The two combined should give you a very clear sense of how to install your own humidifier.

1. Level and trace your humidifier template onto your return air duct.

Source

2. Make a slit in the duct just inside the pattern about 3" long.

Source
  • Place your flat head screwdriver against the duct at a slight angle and hammer it into the metal.
  • Alternatively, you may want to drill a screw in the duct and remove it for an easier start.
  • Twist the screwdriver to pry the slit open a little so that you can start your snips for the next step.

3. Cut out the humidifier and humidistat patterns.

Source
  • Place the humidistat 6" above where the humidifier will be. It does not have to be located on the same side of the return air duct.

4. Mount the humidifier casing and control body.

Top left: the control for this system's zoning. Top right: control body. Bottom: humidifier casing.
Top left: the control for this system's zoning. Top right: control body. Bottom: humidifier casing. | Source
  • Remove the cover and water pad from the humidifier and place the casing into the cutout on the duct.
  • Using 1" long sheet metal screws, mount the casing to the duct by running screws through the provided holes in the casing.
  • This Aprilaire unit requires 6 screws. Pull off the control knob so that you can pull the facing off of the main control body.
  • Using four 1/2" long sheet metal screws, fasten the control body to the duct in the hole you cut. Don't forget the foam gasket that goes between the humidity control body and the duct.

5. Locate, trace, cut out, and install the 6" take off on the supply duct for your bypass.

The take off is installed at the top left in this photo. Notice how it's above the coil and facing the humidifier casing.
The take off is installed at the top left in this photo. Notice how it's above the coil and facing the humidifier casing. | Source
  • Remember, the shorter and straighter the bypass, the better.
  • Warning: If you have air conditioning, avoid mounting the take off right on the coil case, and if that’s the only place you can place it, definitely don't pierce a hole in the coil when cutting into the duct.
  • Now, slide the teeth of the take off or collar into the hole and fold them over to lock it in place.

6. Install the bypass piping.

Install the 6" elbow to the casing. Be sure the bypass damper can swing.
Install the 6" elbow to the casing. Be sure the bypass damper can swing. | Source
  • Your path may vary from mine—just keep in mind that you want to take the path of least resistance when possible.
  • Connect your 6" elbow to the humidifier casing with two 1" screws. The casing has holes at the top and bottom of the damper connection for this. Make sure you adjust the elbow first and check that the damper can swing freely.
  • When cutting straight pipe sections, measure from the edge of point A to the edge of point B and add an extra 3" for your connections.
  • As you complete each connection, wrap tape around them, and install two 1/2" screws in each, across from each other.
  • If it's summer, close the damper. If it's winter, leave it open.

7. Install the drain piping.

Measure to cut your 6" warm air pipe to fit and finish up your bypass. Remember, edge to edge plus 3".
Measure to cut your 6" warm air pipe to fit and finish up your bypass. Remember, edge to edge plus 3". | Source
  • Assuming you have air conditioning or a high-efficiency furnace, you can easily tap into one of those 3/4" lines by cutting in a "tee" and running your pipe from there to the humidifier.
  • You can measure edge to edge plus 1" to get your cuts for straight pipe.
  • Be sure to glue each joint and secure the pipe to the furnace or duct with 1/2" screws.
  • You can use pieces of your scrap metal for strapping.
  • If you don't have a drain already, you can run the pipe along the floor to a laundry drain, or you'll have to add a condensate pump to pump the water to its destination.

Finish the bypass by taping the joints and installing two screws to each joint.
Finish the bypass by taping the joints and installing two screws to each joint. | Source
Tap into existing drains.
Tap into existing drains. | Source
Tap into the drain by cutting in a "tee".
Tap into the drain by cutting in a "tee". | Source
Install PVC drain between "tee" and humidifier with the path of least resistance.
Install PVC drain between "tee" and humidifier with the path of least resistance. | Source
Be sure to glue the fittings and secure the pipe.
Be sure to glue the fittings and secure the pipe. | Source

8. Connect your transformer. *Make sure the unit is powered off.*

Source
  • Modern furnaces have terminals on the circuit board marked HUM and NEUTRAL for easier humidifier hook up.
  • Be sure you don't tie into the 24V common by mistake. The NEUTRAL is for 110V use.
  • Use pliers to squeeze your spade connectors onto the transformer's black and white wires.
  • Then, just securely press the black connector onto the HUM terminal and the white connector onto the NEUTRAL.
  • If you don't have these terminals, you'll have to tap into another 110V source using wire nuts.

Humidifier Wiring Diagram

The 24V humidifier wiring is done in a very simple series.
The 24V humidifier wiring is done in a very simple series. | Source
Put your spade connectors on to your transformer wires.
Put your spade connectors on to your transformer wires. | Source
Carefully push the spade connectors onto the circuit board. Black to HUM and white to the 110V Neutral.
Carefully push the spade connectors onto the circuit board. Black to HUM and white to the 110V Neutral. | Source

9. Run the thermostat wiring (low-voltage wiring).

Connect your red and white low-voltage wires to the transformer. It doesn't matter which color goes to which side; just remember where they're going.
Connect your red and white low-voltage wires to the transformer. It doesn't matter which color goes to which side; just remember where they're going. | Source

I have chosen to run most of my wiring through my ductwork, in this example, because it keeps it protected and looks much neater. However, with so many options and situations, I've provided photos and a wiring diagram that I believe will give you a better idea of how to tackle your specific needs. Just keep this in mind:

  • Any wiring outside of the duct from the ceiling down should be protected by some sort of flexible conduit.
  • Don't let the wire rub on sharp edges.
  • Make sure you make good connections. Don't over tighten, but be sure the wire is secure in whatever terminal type you're using.

Here are the connections to the humidifier control. Red is from the transformer and white goes to the humidifier.
Here are the connections to the humidifier control. Red is from the transformer and white goes to the humidifier. | Source
I poked a hole in the duct and inserted the wires from the humidifier to hide my connections. White is from the humidistat to humidifier unit and from unit back to the transformer. Red is just a continuation from the transformer to humidistat.
I poked a hole in the duct and inserted the wires from the humidifier to hide my connections. White is from the humidistat to humidifier unit and from unit back to the transformer. Red is just a continuation from the transformer to humidistat. | Source
Here, I protected my wiring from the duct to the furnace.
Here, I protected my wiring from the duct to the furnace. | Source

10. Install the water line and valve.

Notice how the needle is recessed into the rubber gasket and that the gasket is seated on the valve so that the curvature of the two match up.
Notice how the needle is recessed into the rubber gasket and that the gasket is seated on the valve so that the curvature of the two match up. | Source

Again, I think the photos will help you the most, so as you look at those, keep in mind:

  • Make sure the rubber gasket is seated properly, the "tee" handle is tightened to the mounting bracket, and the valve needle is retracted when mounting the valve to the hot water line.
  • Don't over tighten anything, and use two pairs of pliers to make sure you don't twist things as you tighten.
  • Once you've cut the line and completed the install of it, twist the valve "tee" handle all the way down to pierce the main and then loosen it to open the valve and allow water to flow to the humidifier.
  • Make sure you know where the nearest water shut off is.

In case there is a problem once you pierce the line, you'll have to shut off the water to that pipe to stop the leak and fix the issue. It is probably just a matter of tightening the connections a bit more, but worst case scenario—you can install an inline valve and make the repair to the main at the same time using push fittings. Simple as pie.

Install the saddle valve on the hot water line with the discharge pointing toward the humidifier. Be sure everything is securely tightened but not overtightened.
Install the saddle valve on the hot water line with the discharge pointing toward the humidifier. Be sure everything is securely tightened but not overtightened. | Source
This is how you place the nut and ferule onto the 1/4" water line you are about to connect.
This is how you place the nut and ferule onto the 1/4" water line you are about to connect. | Source

11. Re-install the water feed tube, panel and humidistat cover.

Source
  • Place the tube in the valve.
  • Slide the nut and ferrule up to the valve
  • Tighten the two by using one plier to hold the valve and the other to tighten the nut.
  • With the tube connected, tighten the valve down to pierce the main.
  • Then, loosen it to allow water to flow.

Source
  • Insert the feed tube into the water panel housing where it was
  • Snap the panel back into the humidifier by putting the bottom in first and snapping the top back into the humidifier housing.
  • The humidistat cover will also just snap into place.
  • Put the knob back on the control post. The knob only goes on one way.

12. Run a test cycle.

Run a test cycle and replace the cover. Your humidifier installation is done if the test cycle was good.
Run a test cycle and replace the cover. Your humidifier installation is done if the test cycle was good. | Source
  • Make sure the power to the furnace is turned back on and that the main thermostat is set high enough to make the furnace run.
  • Place the doors back onto the furnace and turn the humidistat all the way up or to the "test" marking.
  • Within a minute or so, you should hear the "click" of the humidifier's solenoid valve opening and the water flowing into the water panel.
  • You can remove the hose to see if the water is coming, but when you do, make sure you point it at the panel near the bottom to catch the water.
  • If all is well, replace the cover on the humidifier and adjust your humidity control to your liking.

Setting and Controlling the Humidity Level

Once your humidifier installation is complete—and you've checked that all of your plumbing connections are leak free—you can run a test to make sure it's operating properly and set your desired humidity level.

Turn the humidistat all the way up or to the "test" level. This will force the unit to operate. You can confirm this by listening for the "click" of the solenoid valve open and for the flow of water and drainage coming from the unit.

The recommended starting setting will vary a bit based on the region you're in. That being said, 35-45% is the suggested range for most of us, but we want to ease into that. Start at 30% and let the humidity settle into the home before deciding to make adjustments.

Remember that things will begin to expand and soak up the initial humidity, so you won't get a true feel for what the proper level is until you let the unit work for a while and equilibrate. Consider waiting 4-5 days before fine-tuning the settings.

Tips for making adjustments:

  • Do a little at a time. You'd be surprised how much 1 or 2% can make a difference.
  • If windows and horizontal surfaces feel damp, the level is too high. This can cause wood to take in too much humidity and ice to form on windows.
  • If static is still keeping you from wanting to be near your loved ones, and you feel that the air is still dry, the level is likely too low. You should bump up your humidistat until you're comfortable (without making your home too damp).
  • Once you find a level that you're comfortable with, mark it on the humidistat so that when you shut down the humidifier for the summer, you'll know where to set it again when cold weather swings back in.

Basic Humidifier Maintenance and Parts

One of the best things about humidifiers is that they're so simple to maintain and there are only a couple of working parts.

Below are photos of these parts as well as a brief description of each one for easy reference, should you need them. As far as maintenance goes, just replace your water panel as needed.

A water panel doesn't have an exact lifespan. It largely depends on the water that it uses and the home that it's in. Be sure to check it for mineral build-up and/or deterioration. These are signs that your water panel needs replacing.

Other than that, remember: When we have plenty of summer humidity, and we want our humidifier shut down, turn your humidistat all the way down or off, and shut the bypass damper between the unit and the plenum (turn it to "summer").

This may be a good time to replace your water pad or panel since it's also a good time to replace your furnace filter with spring coming.

Tip: Change your filters after you do your spring cleaning since you'll likely be stirring up dust.

Humidifier Parts

Click thumbnail to view full-size
The water panel casing holds the water panel. The top comes off so that you can slide the panel out for replacement.The solenoid valve opens and closes when the humidistat tells it to and allows the water to flow as needed.The feed tube runs from the solenoid to the panel.This is a simple 110/24V transformer. It's easy to find if yours ever goes bad.
The water panel casing holds the water panel.
The water panel casing holds the water panel. | Source
The top comes off so that you can slide the panel out for replacement.
The top comes off so that you can slide the panel out for replacement. | Source
The solenoid valve opens and closes when the humidistat tells it to and allows the water to flow as needed.
The solenoid valve opens and closes when the humidistat tells it to and allows the water to flow as needed. | Source
The feed tube runs from the solenoid to the panel.
The feed tube runs from the solenoid to the panel. | Source
This is a simple 110/24V transformer. It's easy to find if yours ever goes bad.
This is a simple 110/24V transformer. It's easy to find if yours ever goes bad. | Source

Aprilaire 600M Humidifier Kit Review

Aprilaire 600 Humidifier Auto
Aprilaire 600 Humidifier Auto

Aprilaire is one of the most well-known names in air quality appliances. I have used their products for years and feel they live up to their reputation. I am not in anyway affiliated with Aprilaire; I just like the product and feel it is well-made and installer friendly. When properly installed, used, and maintained, I know you'll be happy with their products.

The 600M is a simple, manually operated damper and stat model humidifier for larger homes. Aprilaire also has many models that offer options for outdoor humidity sensing and more automated functions to go along with a variety of other HVAC air quality accessories.

 

This Concludes Our Session of Humidifier 101

Perhaps this is more than you ever wanted to know about humidifiers, but I wanted to provide a complete guide, not just on installing a whole-house humidifier but also all the things that go with it.

Whether it be the Aprilaire unit I used in this example or any other humidifier brand, all of this information is applicable, and the project should only take about four hours to complete for the average homeowner.

Steps 9 - 12

Click thumbnail to view full-size
Connect your red and white low voltage wires to the transformer. It doesn't matter which color goes to which side just remember where they're going.Here are the connections to the humidifier control. Red from transformer and white goes to the humidiferI poked a hole in the duct & inserted the wires from the humidifier to hide my connections. White from humidistat to AprilAire unit and from  AprilAire unit back to the transformer. The red is just a continuation from transformer to humidistat.Here I had to protect my wire from the duct to the furnace. See how the needle is recessed into the rubber gasket and that the gasket is seated into the valve so that the curve of the 2 are the same.Install the saddle valve on the hot water line with the discharge pointing toward the humidifier. Be sure everything is securely tightened but not over tightened.This is how you place the nut and ferule onto the 1/4" water line you are about to connect.Place the tube in the valve. Slide the nut & ferule up to the valve & tighten by using one plier to hold the valve & the other to tighten the nut. With tube connected, tighten the valve down to pierce the main and then loosen it allow water to flow.Reinsert your water panel bottom first and click it into place at the top. Put the water feed tube back into the hole at the top of your water panel casing.Run a test cycle and replace the cover. Your humidifier installation is done if the test cycle was good.
Connect your red and white low voltage wires to the transformer. It doesn't matter which color goes to which side just remember where they're going.
Connect your red and white low voltage wires to the transformer. It doesn't matter which color goes to which side just remember where they're going. | Source
Here are the connections to the humidifier control. Red from transformer and white goes to the humidifer
Here are the connections to the humidifier control. Red from transformer and white goes to the humidifer | Source
I poked a hole in the duct & inserted the wires from the humidifier to hide my connections. White from humidistat to AprilAire unit and from  AprilAire unit back to the transformer. The red is just a continuation from transformer to humidistat.
I poked a hole in the duct & inserted the wires from the humidifier to hide my connections. White from humidistat to AprilAire unit and from AprilAire unit back to the transformer. The red is just a continuation from transformer to humidistat. | Source
Here I had to protect my wire from the duct to the furnace.
Here I had to protect my wire from the duct to the furnace. | Source
See how the needle is recessed into the rubber gasket and that the gasket is seated into the valve so that the curve of the 2 are the same.
See how the needle is recessed into the rubber gasket and that the gasket is seated into the valve so that the curve of the 2 are the same. | Source
Install the saddle valve on the hot water line with the discharge pointing toward the humidifier. Be sure everything is securely tightened but not over tightened.
Install the saddle valve on the hot water line with the discharge pointing toward the humidifier. Be sure everything is securely tightened but not over tightened. | Source
This is how you place the nut and ferule onto the 1/4" water line you are about to connect.
This is how you place the nut and ferule onto the 1/4" water line you are about to connect. | Source
Place the tube in the valve. Slide the nut & ferule up to the valve & tighten by using one plier to hold the valve & the other to tighten the nut. With tube connected, tighten the valve down to pierce the main and then loosen it allow water to flow.
Place the tube in the valve. Slide the nut & ferule up to the valve & tighten by using one plier to hold the valve & the other to tighten the nut. With tube connected, tighten the valve down to pierce the main and then loosen it allow water to flow. | Source
Reinsert your water panel bottom first and click it into place at the top. Put the water feed tube back into the hole at the top of your water panel casing.
Reinsert your water panel bottom first and click it into place at the top. Put the water feed tube back into the hole at the top of your water panel casing. | Source
Run a test cycle and replace the cover. Your humidifier installation is done if the test cycle was good.
Run a test cycle and replace the cover. Your humidifier installation is done if the test cycle was good. | Source

Questions & Answers

    © 2014 Dan Robbins

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      • Cre8tor profile image
        Author

        Dan Robbins 4 days ago from Ohio

        I really can't say for sure on a specific board but I do know the neutrals are often sectioned off on their own sort of and if they are all occupied there spade terminal splitters you can get that will turn a single into a double.

      • Cre8tor profile image
        Author

        Dan Robbins 4 days ago from Ohio

        There should be a neutral section on the board that's common to all the 110 circuits, it just may not be located right there by the HUM terminal.

      • profile image

        Eric 8 days ago

        Follow up to my last post, the circuit board is a Nordyne 624790-A for reference. In the corner of the board, it has two terminals labeled "LINE N" and a terminal labeled "XFMR N", are these the dedicated neutrals I can hook up to? (all three are currently in use) If so, does it matter which one I hook up to?

      • profile image

        Eric 8 days ago

        I have the Aprilaire 500m unit. My circuit board has the HUM (110v) terminal but no neutral terminal. Where else can I hook the white wire from the transformer?

      • Cre8tor profile image
        Author

        Dan Robbins 2 weeks ago from Ohio

        It sounds like you have an upgraded model. Keep in mind the example in my article is using a 600M...a very simple unit. You should have wiring diagrams in with the unit you bought that will help with yours.

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        Aprilaire 2 weeks ago

        Thanks for putting so much effort into this article. Helps but it still didn’t work. I have on my April aire humidistat r,c,w,h,h,gf,a,b, g,odt

        So the diagram doesn’t workout.

        I bypassed it for now so it will run. Any suggestions will help

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        Author

        Dan Robbins 3 years ago from Ohio

        Yes but not much and your installation guide should help you with the outdoor sensor wiring. I don't remember off the top of my head however I know it's quite simple. The rest of the wiring is basically a circle going from the furnace to the stat (red), from there to the humidifier solenoid (red still) and back to the furnace (white/common). The stat acts as a switch triggered by the humidity reading so that it won't come on unless the humidity is less than what you a setting it to call for so the 24v just goes to the stat when the heat comes on but only makes it to the solenoid if the stat then "closes the bridge" allowing it to pass to the valve so it will open. This is where the work is done so it then sends the negative voltage back to the common on the furnace and that's it.

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        Kenny 3 years ago

        Thank you soo much. Very helpful. But the wiring still confuses Me. I have an automatic 500 aprilaire with outside temperature. Will wiring be different for me.

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        Dan Robbins 3 years ago from Ohio

        Hello Millionaire Tips. The only time you have to worry about mold with a humidifier is if it's not used properly. People who say their humidifier caused mold usually have it set too high and/or forget to shit it down in the winter. Like most products, it just takes proper care...I highly recommend having a humidifier. It's one of the most beneficial of hvac accessories and affordable. Thank you for reading!

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        Shasta Matova 3 years ago from USA

        Congratulations on being one of the top 10 hubs for Friday. I've seen advertisements for the Aprilaire humidifier, and have been seriously tempted. Do you have to worry about mold with a humidifier?

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