20 Most Recent Aprilaire 400 Humidifier Questions & Answers

Somewhere in the mess you have described there is a short that is compelling the transformer to put out more current than what it is designed for. It gets hot, really overheats, insulation melts, and the wires melt. Ergo blown transformer.Problem is with whatever that unit is plugged into/powering..

Not happy either. I bought 3 Aprilaire 400 for my house (3 zones). I picked this style since I have attic installation and did not want to run drains. The first night I expected a major air quality improvement but no change in humidity. I have installed humidifiers before so I know the drastic improvement they make. So I watched for a season and still no humidity improvement. Absolutely nothing at all. Same exact observation as you all described. Only the bottom of the media was wet. I'm dissatisfied with Aprilaire 400. Do not buy! Since I installed humidifiers before and understand them I am converting the Aprilaire 400 to work like a Aprilaire 600. I simply unwired the float sensors, removed the floats/lid and using a knife cut some of the plastic cups so the water would drain well. I also cut open the plastic exit port some too so it wont clog from dust globs. I obviously added drains. HUGE RESULTS. On the very first cycle on the humidity in that zone went from 25 to 48. I am watching carefully. -GK

Here is a installation guide http://electronicaircleaners.com/database/documents/aprilaire_400_installation.pdf

Your humidifier is a bypass type. The only voltage needed is 24vac to open the water valve. Air only flows through the humidifier when the furnace blower is running, and the wet pad will add very little humidity if the furnace is not running and heating the air before flowing through the wet pad in the humidifier. It is best the water valve is only energized when the furnace is running. Some furnaces have a connector on their control boards labeled HUM for this purpose. Test it's voltage when the furnace is running because some will output 110vac instead of 24vac you need.

This may caused by a weak solenoid or loose wiring comncetions to the solenoid. Make sure all wiring connections to humidifier amd solenoid are tight and secure.

This is either the solenoid or a loose low voltage wire. Make sure all the wiring connections are tight, if they are the solenoid if bad and will need to be replaced.

Hello, if your asking how to replace the water all you need to do is buy a replacement water panel, and make sure the side with the black mark is pointing up.

Hello, check to see if you are getting 24 volts to the solenoid valve, if you are and the solenoid does to click to let the water in it must be replaced. If you are not getting 24 volts start at the transformer and work your way toward the solenoid valve to find where the voltage stops.

If your humidifier is equipped with a Digital Humidifier Control with Water

Panel change indicator, after replacing the Water Panel, turn the control

knob to the "Test/Reset" position until the "Humidifier On" light blinks to

reset its timer. (Blower must be operating and HVAC calling for heat.) Be sure

to turn the control knob back to it's original setting. If the "Humidifier On"

light continues to blink, your humidifier is in Test mode. DO NOT LEAVE THE
CONTROL IN TEST MODE OR HUMIDIFIER WILL NOT OPERATE.

Hi,
Sounds like you are not getting the proper voltage to the solenoid valve...
Check for 24v coming off of the transformer...that may be 24vac not vdc...

Then check to see if there is power coming from the humidistat...
unhook the wires to check for the power at the solenoid valve...
check across the two wires...

if there is power the valve is bad and that alone will cost about 90 bucks with shipping...
if there is no power trace back and see where the power stops at...

heatman101

The first thing to check is if you are getting 24 volts to the solenoid valve, if you are and it is not opening to let the water in then u need a new solenoid vlave. If you are not getting 24 volts check to see if you are getting 24 volts at transformer, if not then turn off power to to the transformer and check itls continuity on the secondary side, if no continuity then the transformer must be replaced. Also make sure the saddle valve is open and that the inlet strainer at the solenoid valve is clean and no sediment is built up in it restricting water flow.

I don't really have a "solution" but you might want to check the resivoirs for lime/calcium buildup as they can defeat the signal by the sensors thinking that the system is full of water. Some vinegar and a toothbrush resolves this. The other possibility is that your sensors may be deflected below (not in contact with) the resivor bottom.

Check to see if you are getting 24 volts from the transformer, if not, turn off power to the transformer and check the resistance of the secondary side, if no resistance the transformer is bad and need to be replaced. Also check to make sure all the wires are secure. If you are getting voltage at the transformer then bring power directly from transformer directly to solenoid valve and it should click open and let the water through, if it does then either the sailswitch/current sensing relay is bad or humidistat is bad.