Aprilaire 700 Automatic Whole Home Humidifier Installation 

best wiring introduction for humidifier I have ever watched. Clear and easy to be understood Thanks.

Dude...I didn't have time to install mine, so I hired a contractor. They left and it wasn't working. I went down and they didn't even install the transformer. The lights on the panel come on, but no water flows and the fan doesn't come on. Then I see the transformer sitting on the side and found your video. Going to have to re-wire the whole thing now. Thanks man

I think your wiring is not what they have on aprilair manual. First, the power at the R and C of humidifier should be supply from furnace 24v R and C not from the aprilair transformer. Second, the 120 volt power to the aprilair supplied transformer should be on constant power supply source. You can do this by put another box next to the existing box on furnace which has a switch to turn off the furnace. I think it should be on a GFCI outlet for safety. I believe you have the model 700 which is automatic not the 700M which is manual. I think that need an outdoor sensor to turn the humidifier on. the manual model can be turn on by a current sensor relay. The Gf terminal on the humidifier will activate the furnace blower fan when running with out the furnace in heat mode when more humidity need for the house. thanks for posting this video

Thank you Ron. You saved my bacon. You explained the wiring of the transformer 24VAC/10VAC and the thermostat. I'm adept at reading automotive electrical schematics and even after you explanation, I didn't decipher the schematic the same way, but followed your lead and everything is up and running. Thank you!

Ron, I am impressed with your work. I have a couple concerns though. 1)The HUM terminal is really the terminal you want to use. HUM literally means Humidifier. The EAC terminal is really for the Electronic Air Cleaner. It is active whenever the fan is running on any speed, so the electronic air cleaner can only run when the fan is on. The humidifier should only be active during the heating season. When the A/C is on during the cooling season, it is actually de-humidifying and reducing the temperature of the air. If you run the a/c and humidifier at the same, they are fighting each other. 2) The saddle valve will eventually become clogged or may leak. Also using the saddle valve does not comply with many local codes. 3) The transformer is 24 volts not 10 volts. I think you are looking at the 10 VA power rating. 4) Lastly the wires should be squared off and held in place with plastic clips. This makes the job look much more professional. Also none of this wiring needs to be 12 gauge wire. This the most impressive none pro I have seen. Thanks for sharing it.

Thanks for taking the time to put this video together! I used this in combination with the wiring guide. Would have never figured out the EAC wire. Note to others... my circuit board had a positive and neutral EAC port. Accidentally hooked to EAC neutral in error. The positive EAC port was buried behind other wires in my unit.

Omg good job!!! I did a video on the small handheld humidifiers but my skill will never extend to this! EVER!! Thank God people like you know how to do this stuff

I realize this video is 2 years old, but I couldn’t resist. This video shows, how a person with only an elementary knowledge of Electric wiring can actually pull this project off, without killing him self in the prices. Pretty amazing!

Just want to thank you for this video. It's the only one that I could find that explained everything so well for this unit. Very informative. Everything worked out great.

Ron: Thank you so much for putting together such a helpful video. I just installed mine. Your guidance was awesome, especially wiring the controller. I was replacing a very old humidifier unit. So, most of the work was easy and I did not use the outdoor sensor. your video made my wiring work much easier. Thank you.

You're the best teacher! I understood everything you said, and it works! TY

First video with good details and I’ve watched 15 of these damn videos now. Thanks for the info

This video saved my bacon! Thank you again for saving me $ and helping me with the wiring. I couldn't figure out if I was supposed to use both red and white wires on the low voltage side of the transformer. You answered it! :)

Thank You for the straight forward video! I knew it would be right on when you admitted to missing the small manual.... Like I have done dozens of times! Hate plumbing scares me also..... Thanks Again Wes

Hey Ron, thank you for the great vid, it showed me I absolutely can do this myself! I think ole Rich down there needs new speakers. Anyways, just something I figured out recently while changing out my light switches, and not being an electrician myself, is that you can just slide the wires under the plate behind the screws. There are corners missing, so like with the red and white wires on the left side furnace board you can slide one straight up in to each side and just tighten the screw. No wrapping around the screw and no wires trying to pop out the sides. ;)

Solid video. Really answered some questions about the difficulty of this job.

Great detail! Thanks for showing every part of the system!

Thanks for the detail you showed with the wiring. Helped me out a lot!

Awesome tutorial. You were well thought out and articulate in your process. Best one out there. Thanks bro.

I have been searching for a wire specific video, you nailed this and I thank you so much!

The transformer is 120v on the primary side and 24v and com on the secondary side. 10mva is a secondary rating for the transformer and not one side or the other of the transformer.The 2 brown wires are 24v and com and the humidistat is a simple break switch that can used to break the 24v wire or the com. The 24v can be picked up from the HUM terminal or from the W terminal(this will bring it on in heat only). It can come from the R(24v) terminal but will have to be turned off in the summer manually.

Thanks so much. I had watched your video and tackled it myself also following instructions. I wasn’t getting it to click so I came back to your video. I had the 10v and 24v wires backwards. Thanks for your help 😀

I am about to do this install and have been watching your video for how to..thanks for the great tips!

Thanks for your post. Your right, the wiring diagram made it seem like you needed to run a wire all the way back to the thermostat. your video was the only one that showed how you intercept it at the furnace.

Thank You! I was having trouble with the G and Gr and now I understand! Awesome and informative video!

Terrell Lowry , your you tube video for installing a aprailair 700 series Humidifier was very informative

Thanks Ron, Great vid. Couldn't have done it without your video.

Just want to add my thanks for making this video. Helped me solve a wiring problem I had that was driving me nuts.

I think you're mistaken about the transformer, but your circuit board info helped. Thanks! The "ten" on the transformer is not ten volts, it's ten volt-amps (VA) of 24V. It's just hot and neutral.

Thank you for taking the time to post.

Hook up the primary(black&white) side of the transformer to the switch. That way the auto feature will function as intended.

Very informative. You already saved me a lot of trouble I might have had.

Interesting point on the each dock. The the fan would have to be on "on" full time so the controller sets the humidity level

Ron, thanks for the video. It gave me the confidence to go ahead and attempt the wiring. This is the best video that I found regarding the wiring of the Aprilaire control unit. I just completed my installation tonight and it seems to be working properly. I'm not sure if I could have completed my project without your help.

Thanks for the video. Right at the end you said not to use tin snips, due to the sharp edges… but you didn't recommend what to use instead. I've done a fair amount of electrical and plumbing, so that stuff doesn't scare me, but getting the cutting and fit right has me concerned, as I haven't messed with HVAC before. Thanks!

Great video, very informative Ronaldo Nazario!

Thanks! I appreciated the wiring explanation.

Ron, the video is good, however you have made a serious error about the transformer. It is a 120V to 24V transformer but the 10V you saw it really a 10VA description. It means 10 volt-amps, which is not volts but a power rating. Volts-amps is the wattage rating of the transformer. Actually, Watts is the product of volts (V) and amps (A) and power factor (P.F). Often for transformers the power factor is so close to 1 that is often omitted. This transformer draws about 10 watts. That simple.

Thanks. Great video. I loved the tips. Will get my installed this weekend and I know your video has saved me significant time.

I just wanted to thank you for the video. I am no slouch to wiring but this system had so many different examples on how to wire it but your solution was the ONLY one that worked correctly. Thank you very much :)

One brown wire goes to the C terminal on the board and the other brown wire comes from the 24v source through the humidistat.

Thanks for the video, just wanted to add that the 24v transformer needs to be connected to the furnace board using the black and white wires. White to neutral and the black to the eac terminal. I did not realize this and that the wire running from the brown wire thru the transformer gets ran thru the two screws on the bottom of the transformer. Also as others have said get a sharkbite tee stop instead of using the provided saddle valve. I also used a steel braided 1/4" fridge hose instead of copper tubing, we will see how that works but i am sure it will be fine. I didnt have the tool to bend copper and i did not want to pinch the line

Hey man great job i do hvac and you explained everything very well

Thanks for the great video! Just installed my first humidifier with your info!

Thanks Ron, this was a very informative video. I am planning to install my own shortly, and this will help tremendously

Thank you.

Saved me a lot of time. Thanks!

so the transformer black and white wires go to the EAC (black)/ N (white)....excellent...one question though....my transformers white and black wires are bare on the ends where you have the clips....did you need to do that? I originally wanted to do it this way but on the directions (template) its states in bold " DO NOT WIRE TRASFORERMINTO FURNACE BLOWER CIRCUIT"...like on yours at the 1:00 mark (I have the 700 M where you have the digital). In addition to that confusion I also noted the "Model 50 Current Sensing Relay (if required??).....thus going into the blower and NOT the transformer.....as you now know I am NOT an electrician and have only installed outlets, lighting, and stuff like that

Will it control furnace blower ON/OFF? My humidifier is mist kind and requires heat and blower working together with humidifier. My humidifier also requires furnace blower to work a couple minutes after humidifier switches off automatically to distribute all the moisture collected in the duct. If blower stops the same time with mist humidifier moisture still will sit inside plenum and makes it rust. Will this Humidifier Control have this setting so furnace blower work few minutes after humidifier switched off?

Very good video

Great video, but I do need to add that your control should be above your humidifier. And those saddle valves eventually leak. Aprilair will always put that saddle valve in the box. in my experience, I've always thrown those saddle valve out and put in a add a line ball valve. granted you have to drain the water from your water heater but they work way better. great video though.

Have you changed any of the wiring hook up to different ones or is this video still accurate. Any chance you can tell me what wire to get to complete this or a buying list? Thank you

Good guide. my problem was how to wire the transformer secondary. I was confused by the Aprileaire instructions regarding the 24 VAC. The transformer supplied has 2 terminals, one 24 VAC and one 10 VAC. Your video was the only one I found that clearly told how to wire to the two brown wires on the solenoid. Thanks.

Thank you Ron.. Its very detailed and helpful to understand how this product works. This helps me to fix my issue.

Don’t connect to EAC! A regular power source such as the switch or a nearby outlet will do and keep the auto features on constantly instead of just when the fan is on.

Tim Whiteman, I cannot reply directly to your comment for some reason. To install the saddle valve I shut off the cold water to the hot water heater. I ran the hot water in my basement in a sink to get the water pressure out of the line. The saddle valve itself has it's own shut off mechanism when you turn it all the way to the right. I don't think you *have* to shut off the water for this. If you did it this way, I would recommend making the connection on the Aprilaire unit before installing the saddle valve to avoid water from squirting out the end that is supposed to connect to the Aprilaire unit.

Saddle valves will eventually leak. Always. Change it out for something more permanent and durable.

U don't need the transformer that comes with the humidifier.. run 5 wires from your furnace, r,c,w, and you break g.. then run a jumper wire on the humidifier control from r to h and connect the 2 wires from the humidifier to c and the other h terminal on the control...humidifier with digital control will turn the fan on every HR to sample the air and will humidify if needed. You turn that option on and off by using the blower activation switch.. if you run the humidifier without the heat you need to plumb it to a hot water supply.. if you turn off blower activation then the humidifier will sample air only when heat turns on or you turn the fan switch on your thermostat to on.. also there is no 10 volts, heating systems use 115v and 24 volt. So connect your wire back to the hum terminal and turn blower activation on.. you don't use or need eac. Hum is humidifier and eac is electronic air cleaner

Great job, Ron! I used your vid to replace my Honeywell HE265 with a new Aprilaire 600. I just couldn't understand the transformer install by reading the instructions and diagram. Glad you figured it out! Now my only problem is that the RH value on humidistat goes through the roof (quickly ramps up from 50%) when I manually turn the furnace blower on, which of course means the humidifier does not turn on since it thinks the RH is already higher than the highest 45% (setting 7) allowed by the humidistat. Automatic blower activation does not work either even when the humidistat displays the "real" RH of about 25% when the blower is off. Perhaps the two issues are related. I plan to call Aprilaire tomorrow for troubleshooting since I can't find anything online. My guess is that I need to relocate the humidistat as the immediate RH reading spike is probably due to it sensing lots of moisture from the humidifier. I welcome ideas in the meantime if anyone has any.

Nice video - when I get in there this week I might have some questions for you - I got the 600 series and there's a lot of confusion about needing a relay or hooking up correctly so it only comes on when the fan is running - I think you did that in this video but you had to move some wires? I don't want to mess with the wiring of the furnace. Other than the G wire. I hope I can figure this out - I just don't want it running water into the drain constantly (pump). I want it to only come on when it calls for water and the fan is on.

I see the black and white coming from the transformer. if those get hooked up to constant power, where are the black and white that hook up to the panel coming from? the part of the video where you first hooked it to the hum and then moved it.

Great video, Ron! It really helped me with the wiring of my AprilAire 700. Question about the wiring from the transformer to the circuit board: You hooked up the black to EAC and the white to "neutral". My circuit board doesn't have any terminals labeled "neutral", but it does have a few labeled "spare." Are neutral and spare the same thing? Thanks in advance!

Enjoyed your video. Very informative. I'm replacing an older model with the control in my dining room. Do you know if the 700 M can be controlled from there too. Would rather not have to run down the basement every time there needs to be an adjustment.

Thanks! it was helpful

+Ron Stack thanks for this very informative and most needed instructions! I have everything hooked up and ready for the wiring. I notice that you have your 700 setup in Manual mode. I am going for the Automatic. Questions: 1. Your 120v input to the transformer - Narrative between 6.20 to 7.50 - suggests that if you want the humidifier to run when the furnace fan runs, then you want it hooked up to EAC. If on Auto mode, there is a Blower Activation ON/OF switch on the control. According to the manual, this feature turns the furnace fan on for an air sampling. You can see my confusion now. Should I still go for EAC? Or just hard wire (have an outlet nearby). 2. Outdoor sensor - assume the wire is just regular thermostat wire?

thanks. Excellent Wiring Instruction. I have a question, does the wiring of Aprilaire 700 & 600 digital controller are the same?

Thanks for the helpful video

how did you install the shut off valve? did you just shut down the water on the cold water side? great video as well.

Hello Ron. Thank you for the great video. One question, on my supply side i do not have much space above the AC coil. How far the humidifier must be from the coil?

Hey great video. Did you plug in the fan unit to a regular outlet? Or did connecting the solenoid directly to the furnace take care of the fans power needs? Thanks Ryan

Very helpful. Thanks!

Does your drain line from the humidifier flow a lot of water? I've heard this unit wastes quite a bit of water which would be a problem for me since we're on a well system. Also I'm concerned about the hot water usage. I watched one vid where the water was flowing pretty freely.

I am confused. The Aprilaire support told me the transformer is getting 120V then step down to 24V. In your configuration, the transformer connects to EAC which is a low voltage port that provides 24V. My 700A has its transformer connects to the line voltage which is 120V.

Ron, thanks very much for this video. I couldn't have done the electrical part of the job without it. I just finished installing the unit. It seems to be working great. One question: is it normal that water is flowing through always when the humidifier is running? It seems to be lots of water wasted. Thanks again for the great video.

I'm wondering if the Aprilaire 500 has the same transformer. The two black and white wires are 18 gauge. Why did you got with 12 gauge to connect those to the board?

Thanks man!

Great videos. I have a 700 with manual control. I would like to update to an automatic digital controller. Your suggestions! Thanks.

Thank you, thank you, thank you. The installation wiring instructions that come with the unit are flat out wrong. It says to "Connect the 24 volt side of the transformer to one of the "H" terminals on the humidifier control and to one of the humidifier solenoid valve wires. Connect the other solenoid valve wire to the other "H" terminal" After watching your video I realized it should instead read: Connect the 24 volt side of the transformer to one of the "H" terminals on the humidifier control and CONNECT THE OTHER SIDE OF THE TRANSFORMER to one of the humidifier solenoid valve wires. Connect the other solenoid valve wire to the other "H" terminal.

Don't ever use a saddle valve! I'd use sharkbite before I use that!

Is it normal for the humidifier to run when the furnace is off? I mean when I turn the dial on the control unit to the lowest setting and the heat/blower both off the humidifier kicks in and the water starts to run. I want it to run only when the heat is called by the thermostat. Does this make sense? TIA

I say put an add a line ball valve because it's recommend in Minnesota. our inspectors won't let us put the saddle valves on. just sayin

If yo can read this. Please invest in a steam humidifier, the extra power and installation cost are far less than the continued maintenance for continued use. Aprilaire 700 is the best ive used, also opt to install dedicated 220v circuit for more GPD if you have a home larger than 1800 sqft. Honeywell Truesteam is trash.

Great video. So you wired the unit to run every time the fan turns on right. So if you ac or heat.. it runs?

Thanks so much for taking the time to share this video. I am investigating putting in a humidifier for a 3000 sq ft home which is 38 yrs old. Are you happy with this humidifier? What size home/age of home do you use it for? Thanks for any input.

I'm probably more than a little lost...we have the humidifier installed and I am trying to work on the wiring. Where I'm confused is with the transformer. It is mounted to a 110 outlet, so that's good, but what wires are supposed to connect to the 24 and 10 connections? (sorry, beyond a newbie here)

What's that green stuff on the floor of your furnace?

I don’t like the piercing valve,I bought a shark grip 1/2 t reduced to 1/4 with on off valve

Does it always waste that much hot water when it's running?

Take the saddle valve OFF! You have to replace it ASAP with a stubbed out 1/4" ball valve that is nowhere near the vertical hot water tube. I can tell you that the valve WILL FAIL and the slow leak of water is going straight down into your water heater and soaking the insulation around the tank. This will cause 1000s of tiny perforations to develop and you can kiss your heater good bye. I did this to a 3 year old heater and it cost me over $600.00 to replace it. Sharkbite or solder, but get that piece of junk off of your system, please! I just installed a 760 on my furnace and have a 6" stub out (horizontally) from the hot water side and a chrome-plated 1/4" valve on the end. Best money you can spend.

@Ron Stack I have Honeywell thermostat RTH9585WF1004 and is connected to terminal R and C on the furnace terminal, I suppose that is how Honeywell thermostat gets dc power, if I disconnect thermostat from terminal C, it will lose its power source. Is it possible to have connected my thermostat to terminal C and humidistat model 60 connected to terminal C at the same time? I also notice there is a second cable connected to terminal C on my furnace as well (apart from one coming from thermostat) this second cable goes to AC, so in total of 2 cables are connected to C terminal. A third one from humidistat model 60 can be connected to terminal C as well?

can I use icemaker tubing for water feed? I mean are both the same size ? thanks

where does the power cord hook up. Just to a 110 line

Geezzzz can’t somebody make a good steady sharp video of this install?

How far does the unit stick out from the side?

Am not getting 24 volts at water valve. any suggestions??

Saddle valves are NO LONGER ALLOWED in US Code.

By installing on return plenum you are probably pouring the mist into the furnace filter. Probably why AprilAire suggests installing to main plenum. I would suggest you leave this to licensed, trained HVAC personnel. By your own admission, you are not experienced; not trained, and uncomfortable with it.

I have the same model, however, I am not a HVAC technician, so I hired one to install it. These people are certified. I do not recommend doing this yourself. You can damage your system.

Do it yourselfers BEWARE .... The warranty on this unit does not apply unless installed by a licensed HVAC contractor.

You CANNOT use SADDLE VALVES! They are NOT CODE!!!