Question about Aprilaire 600 Humidifier

3 Answers

Aprilaire 600 only operates in test mode...

The system is installed in automatic mode and operates in "test mode" but will not operate out of "test mode".

Outside temperature is 35-40 degrees and the resistance of the temp. sensor at the humidistadt measures ~27 k Ohm (corresponds to the suggested impedance for this temp.). The humidifier is installed in the supply plenum and the humidistadt is located about 5 feet (farther form furnace) away from the humidifier.

On a side note, I used the manual mode resistor with similar results.

Posted by on

3 Answers

Re: Aprilaire 600 only operates in test mode...

Thank you, got my problem fixed, after spend $275.00 call the service man to come. it come up to all about wrong wiring.all working and happy:) now.

Posted on Jan 05, 2008

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer
Re: Aprilaire 600 only operates in test mode...

Well I fixed my problem. It was my fault. I was using installation instructions that I printed from the web, they were for a model 600. The model 600A has a different control and wiring. The model 600 required only one 24V power supply to the R & C terminals. I ran the furnace accesssory power (110v) to the supplied transformer and then to the R & C as required by the model 600. But on the 600A this must be run to the W/G & Cf pair and a seperate continuously powered 24V must be connected to the R&C pair. I bought another transformer, wired everything using the correct diagram and it works great. BTW the E3 code indicates an open circuit on the temperature sensor. Maybe you clipped the wire while stapling it to the joists. Good luck.

Posted on Dec 29, 2007

Re: Aprilaire 600 only operates in test mode...

Call Aprilaire and tell them, this is happining everywhere

Posted on Dec 12, 2007

Add Your Answer

0 characters

Uploading: 0%


Complete. Click "Add" to insert your video. Add


3 Points

Related Questions:

1 Answer

Replaced water panel and the light keeps blinking to change it agai...model 700

Sorry to read about your problem, I hope this helps you out.
did you hit the reset

Digital Humidifier Control (Model 700): (Automatic or Manual mode) Check system operation and reset Change Water Panel indicator by setting the knob to "Test/Reset". With HVAC blower operating and HVAC calling for heat, humidifier will operate for one minute. DO NOT LEAVE IN TEST MODE AS HUMIDIFIER WILL NOT OPERATE.

I tried to help you. Please help me and Rate/Vote on my response. We take the time to answer your question. take the time to rate us.Thanks and good luck

4 Thumbs - Very Helpful
3 Thumbs - Helpful
2 Thumbs - Somewhat Helpful
1 Thumb - Not Helpful

Dec 29, 2010 | Aprilaire 700 Humidifier

1 Answer

I replaced the water panel on our aprilaire 600 humidifier. I adjusted the thermostat to call for heat to test it. When the dial (non-digital control panel for the humidifier) is turned to test/reset,...

Thank you for contacting us with regards to your model 600 Humidifier. The Change Water Panel indicator should flash when the control knob is set to the Test/Reset mode. The flashing indicates that the timer has been successfully reset. However, the humidifier should operate for the first 60 seconds of Test mode as long as your furnace is running. If your humidifier does not turn on, contact your installer. The humidifier may require service.
We appreciate the opportunity to be of assistance.

Brett Phillips
Technical Support
Research Products Corporation

Nov 01, 2010 | Aprilaire 600 Humidifier

1 Answer

Aprilaire 700. It works on fan on mode but not otherwise. It's never on and the humidity reading is always way below the setting. It should turn on automatically to bring the humidity up, right?

It appears your Aprilaire model 700 is wired to only operate when your HVAC fan is operated by your thermostat. Your HVAC installer can wire the humidifier control to operate the humidifier during a heat call, fan call or to turn on the fan when there is a need for humidification. Please contact your HVAC installer to have them change the wiring.

Thank you for giving us the opportunity to be of service

Brad Uselmann
Technical Support
Research Products Corporation

Nov 01, 2010 | Aprilaire 700 Humidifier

1 Answer

Solenoid valve won't open

Check for 24v.hum transformer shuold interlock/power up during blower motor hearing speed operation.Make sure its running.also manual mode resistor has to be installed in control panel.a blue plastic tag w/2 ends.

Mar 15, 2010 | Aprilaire 600 Humidifier

1 Answer

Testing a Aprilaire Humidifier 600 Controller

if it works in the test mode then it should be okay but you can get a humidity gauge from radio shack and set in the house to see how high or low its is. the humidifier is only going to give a max of 45% humidity

Nov 27, 2009 | Aprilaire 600 Humidifier

2 Answers

Aprilaire 700 only works in test mode.

connect two wires at humidifier without any wirng connected if works problem is in wiring or humidistat

Oct 28, 2009 | Aprilaire 700 Humidifier

1 Answer

Is there a url that compares all the whole house humidifiers?

go for the Aprilaire 600 but make sure they install the outdoor sensor and set it up for AUTO operation

Oct 01, 2009 | Aprilaire 600 Humidifier

1 Answer

Aprilaire 600: water only runs in "Emergency" Heat mode

When your unit is on normal the outside unit works and the inside only the fan runs. your heat pump does not remove any humidity when it operates so the installation cotractor did not wire it to operate then. you can change the wiring on the humidifier to operate all the time by wiring it to the fan (g) terminal then it should work just turn it all the way to the lowest humidity when you are in cooling mode.

Jan 07, 2009 | Aprilaire 600 Humidifier

2 Answers

Aprilaire 600 Humidifier


I had this problem several years ago. In order for the water to flow, the outside temperature sending unit must indicate to the controller that it is less than 60F. If not, the unit will not operate outside of test mode. Check the temp outside where your sending unit is (could the sun be heating that side of the house?) and ensure that the circuit to the sending unit is working. I had a bad wire splice inside a wire nut stopping the circuit. Took me a long while to figure it out.

If the outside temp and your sending unit circuit is ok, I wish you luck on your troubleshooting.


Nov 10, 2008 | Aprilaire 600 Humidifier

1 Answer

No water at all

does the solenoid click when in test mode, if not check power to panel/solenoid.

If it does check that restrictor is not blocked

Jan 19, 2008 | Aprilaire 600 Humidifier

Not finding what you are looking for?
Aprilaire 600 Humidifier Logo

1,661 people viewed this question

Ask a Question

Usually answered in minutes!

Top Aprilaire Humidifiers Experts


Level 3 Expert

1033 Answers


Level 3 Expert

1751 Answers

Barrett Palumbo
Barrett Palumbo

Level 2 Expert

1772 Answers

Are you an Aprilaire Humidifier Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides