HVAC

Have HVAC questions? Ask an HVAC Expert for answers

Ask an Expert,
Get an Answer ASAP!

I have the Aprilaire 400 digital humidifier installed but…

Customer Question
Rich. I have the...

Rich. I have the Aprilaire 400 digital humidifier installed but not wired. The diagram provided is not clear to me as I am not versed in wiring. I need easy instructions. There are only a few wires so it can't be that confusing.

Contractor's Assistant: Thanks. Can you give me any more details about your issue?

I am not sure where the transformer goes.

Contractor's Assistant: OK got it. Last thing — JustAnswer charges a fee (generally around $18) to post your type of question to HVAC Experts (you only pay if satisfied). There are a couple customers ahead of you. We can help you for less if you're not in a rush. Are you willing to wait a bit?

Yes

Submitted: 2 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 1 hour by:
1/20/2016
HVAC Technician: Matthew, HVAC Technician replied 2 years ago
Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2,014
Experience: 14 years experience in the HVAC field of service, installation, Manual J & D calculations
Verified

Are you using a current sensing relay?

Ask Your Own HVAC Question
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

And are you going to use the humidistat that came with it to control humidity?

Ask Your Own HVAC Question
Customer reply replied 2 years ago
I'm not sure about the current sensing relay but I am using the didital controler provided.
Customer reply replied 2 years ago
There are threads on the transformer like it attaches to something but I don't know what
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

great. The digital controller has the terminals

R C A B ODT ODT W G H H GF

from your furnace control board where all the thermostat wires hook in you are going to run a wire from the R terminal of that board to the R terminal of the controller.

Run a wire from the C terminal of that board to the C terminal of the controller.

Your outdoor temperature sensor goes into the ODT terminals of controller.

Run a wire from the W terminal of the furnace board to the W terminal of the controler

At your furnace control board you will find a wire under G (should be green wire). You take that wire out of the G terminal and wire nut a wire onto it to extend that green wire up to the controller G terminal.

Then run a wire from the controller Gf terminal down to the furnace control board G terminal.

out of the transformer provided with the humidifier you have 2 low voltage wires. One wire will go up to the controller and hook to one of the H terminals. The other one will go up to one of the two yellow wires hanging off the humidifier itself. Then the other yellow wire on the humidifier will run up and hook to the other H terminal on the controller.

Ask Your Own HVAC Question
Customer reply replied 2 years ago
what does the transformer screw/attach into ?
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

you can mount it just about anywhere you please. It has to hook into 120v somewhere so most often it just mounts right inside the furnace cabinet somewhere so that you can splice off the incoming 120v feed that supply's the furnace power. Will be a white and black wire that is wire nutted into the furnace high voltage feeds.

Ask Your Own HVAC Question
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

You will want to make sure high voltage is off to the furnace. Normally you will have to provide larger wire nuts now that you have 3 wires being put together instead of just the two that are already together in the furnace now for high voltage.

Ask Your Own HVAC Question
Customer reply replied 2 years ago
Okay thanks, ***** ***** be helpful. I'll let you know if I need more assistance.
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

Sure thing, I check back in periodically throughout the day.

Ask Your Own HVAC Question
Customer reply replied 2 years ago
I take it the low voltage wires connect to the terminals on the transformer. I have the transformer mounted but having trouble identifying the high voltage feeds from the furnace.
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

There should be a high voltage wire/whip that runs into the side of the furnace. This wire comes from either a toggle switch next to the furnace or if the furnace is within 6' of the breaker box it will run directly from the box into the furnace. Depending on the model furnace you have the wires will lead into an area where they then wire nut into two wires leading off the furnace. The hot lead (black wire) normally comes off the door safety switch. This switch is pressed in when the furnace doors are securely put on. The white lead (neutral) will lead from the furnace control board up to the wire coming into the furnace either from said toggle switch or from breaker box.

Most often these wire nut connections are behind a little metal box that covers them up. You have to take the little screw out of the little metal box so the side of it pulls off and exposes these wire nut connections.

Ask Your Own HVAC Question
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

http://www.nastyz28.com/forum/gallery/data/500/DSCF0658.JPG in this picture it's on the right side. The metal conduit outside the furnace has the high voltage wire in it and leads into this box where the wire nut connections are made

Ask Your Own HVAC Question
HVAC Technician: Matthew, HVAC Technician replied 2 years ago

And correct. If your particular transformer has two little screw terminals on it and not wires then that is where the low voltage ties in.

Ask Your Own HVAC Question
Customer reply replied 2 years ago
I located the box and attached a photo of it. There are three black wires inside of the box. One comes from outside of the furnace and I suspect it is the lead wire. Of the other two black wires that come from inside of the furnace, one is marked HUM and the other EAC and they are loose and capped off. Also Inside of the box there are two white wires that are fastened together and a blue wire I suspect is the ground. The black wire marked HUM is connected to what looks like a transformer similar to the one provided with the humidifier. Is this unit pre-wired for a humidifier? I'M confused.
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a hvac technicianLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Phil Your Own Question
Phil
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6,938
6,938 Satisfied Customers
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial

Phil is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Phil

Phil

Mechanical Engineer

6,938 satisfied customers

Retired HVAC/ Electrical & Boiler contractor. Industrial

Rick Mather

Rick Mather

HVAC Technician

3,133 satisfied customers

35 years experience, HVAC

Matthew

Matthew

HVAC Technician

2,014 satisfied customers

14 years experience in the HVAC field of service, installation, Manual J & D calculations

Kenton Guidry

Kenton Guidry

HVAC Technician

963 satisfied customers

12 years install/service experience.

Brian HVAC Guy

Brian HVAC Guy

HVAC Technician

953 satisfied customers

I have been an HVAC/R mechanic/technician for 30+ years.

Rick Ridley

Rick Ridley

UK Heating Engineer

871 satisfied customers

Retired But have had 30 years on the tools, Ex CORGI

Tom

Tom

HVAC Technician

770 satisfied customers

16+yrs HVAC/R service. Residential Commerical Industrial

< Previous | Next >

Related HVAC Questions
I replaced my failing carrier humidistat wir. With a Nest
I replaced my failing carrier humidistat wir JA: I'll do all I can to help. How long have you been dealing with this? Customer: With a Nest and have a wiring error JA: How old is the appliance? Have y… read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
I have a aprilaire humidifier what should it be set at. It's
I have a aprilaire humidifier what should it be set at. It's 85 degrees outside … read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Do I have to have my humidistat on in order for my ac to
do I have to have my humidistat on in order for my ac to run.????? … read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
How much water will dump from the humidifier if float was
How much water will dump from the humidifier if float was “stuck” for a 24-48 hr period? This was my second walk through (first was before the storm) then less than 48 hours after, the basement is wet… read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
How do I operate a humidistat. How to operates humidistat. I
I simply turned humidistat on and turned to the current area humidity and assumed the a/cwould come on Nothing happened. HELP … read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
I need an humidistat and a thermostat with WiFi combined for
Hello, I need an humidistat and a thermostat with WiFi combined for my south Florida condo, so that when I'm back in Connecticut I. Can control both the humidity and temperature,,, thanks … read more
gotoman for ac
gotoman for ac
HVAC Service manager and owner
Associate Degree
4,135 satisfied customers
My lennox humidifier doesn't work. it has a fan and solenoid
my lennox humidifier doesn't work. it has a fan and solenoid for water. it is not receiving 24 volts from the lennox furnacde … read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
I'm installing a Aprilaire 600 humidifier with a Aprilaire
I'm installing a Aprilaire 600 humidifier with a Aprilaire Model 60 automatic digital humidifier control into a Honeywell EIM THM5421R. I thought I had the wiring figured out but I'm stuck. Need guida… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Trying to hook up humidifier to furnace and thermostat.
Trying to hook up humidifier to furnace and thermostat … read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
454 satisfied customers
I'm trying to connect/wire from my Wait 6000 humidifier to
I'm trying to connect/wire from my Wait 6000 humidifier to the Lennox EL296UHE furnace. The Wait manual say connect the wires C & W (W1) terminals. But Lennox manual say one wire to terminal C and the… read more
MattR757
MattR757
HVAC Contractor / Owner
Associate Degree
14 satisfied customers
I, I installed a furnace control Board part # 62-24084-82.
I, I installed a furnace control Board part # 62-24084-82. It cycled once and will will not cycle again. all the controls are ok after checking them. any Ideas? … read more
Regan Land
Regan Land
General Manager
Vocational, Technical or Trade Scho
508 satisfied customers
I've recently installed a HM700A1000 steam humidifier and
I've recently installed a HM700A1000 steam humidifier and everything is working fine except that it's not shutting off. It has the yellow LED constantly on which indicates the water level is to high w… read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
I'm wondering if humidistat for my he120 can be tapped onto
Hi I'm wondering if humidistat for my he120 can be tapped onto hum terminal on my furnace … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,870 satisfied customers
How do you hook up a general E2 humidistat to an Acu steam
How do you hook up a general E2 humidistat to an Acu steam 10 humidifier … read more
Daniel Plourde
Daniel Plourde
plumbing, hvac technichian
Vocational, Technical or Trade School
454 satisfied customers
My Aprilaire 700 humidifier is not working properly. The
My Aprilaire 700 humidifier is not working properly. The humidistat on the side of the furnace reads 50% while the actual humidity throughout the house is only 30%. Is this something I can fix myself,… read more
gotoman for ac
gotoman for ac
HVAC Service manager and owner
Associate Degree
4,135 satisfied customers
I want to wire my Generalaire Humidistat to my Furnace. I
I want to wire my Generalaire Humidistat to my Bryant Furnace. I see a dedicated terminal for the Humidifier (HUM), but I do not know where to connect to common (C). I see a vertical row of terminals … read more
Phil
Phil
Mechanical Engineer
6,938 satisfied customers
A quick question on a humidifier: The humidifier goes on at
A quick question on a humidifier: The humidifier goes on at 20 {manual on} but does not shut off when the flame goes off (cool). Where can I find manuals for these humidifiers and what is the problem?… read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 satisfied customers
This is the same guy with the Goodman furnace control board
Hi, this is the same guy with the Goodman furnace control board / transformer. My plumber said what caused the board to fail was a short in the blower motor from water from AC unit backing up into blo… read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x