Replacement Humidifier Water Solenoid Valve 4040 for Aprilaire Whole House Humidifier 220 224 400 440 500 550 558 560 600 700 760 768 | 24 Volts | 2.3 Watts | 60 HZ from an AMERICAN Owned Company

worked well

AN UNUSUAL PROBLEM caused me to buy this valve: After the furnace came on, I never heard the valve click. With my DVM, I measured the AC voltage across the solenoid: With the furnace off, the voltage was about zero (or only tenths of a volt). With the furnace on, the voltage rose to 117 volts. Wow! Way too much! (The correct reading is 24 VAC.)“HUM” CONNECTIONS. My Carrier furnace CPU Board has two humidifier terminals: One terminal bears the label "HUM." The other terminal is "HUM 24VAC." The red humidifier wire connected to the “HUM” terminal. (I checked the voltage inside the furnace. When the furnace came on, the voltage across the red and white wires measured 117VAC.) Conclusion: The technician who worked on my CPU Board last year connected the humidifier wrong! His error probably burned out my solenoid.WARNING. Know what you’re doing, or don’t try this next part! After switching off the furnace, I moved the red humidifier wire from "HUM" to "HUM 24VAC.” The white humidifier wire was already on the "C" (common) terminal. I left the white wire alone.REPLACEMENT. I shut of the water supply to the humidifier. Then I installed the new solenoid valve. I set the humidifier to "35%" (Normal). Next, I opened the water valve, and switched on the furnace. When the furnace came on, the new solenoid clicked. The solenoid voltage measured 26.7VAC (Acceptable). Checking the water outlet, I noticed a trickle of water flowing (Normal). When the furnace shut off, the outlet trickle diminished to nothing. Perfect!STRAINERS. With the valve, I received two input water strainers. One of these strainers was already in the input pipe. I’ll save the other strainer as a spare.THANKS. Weeks after valve replacement, the humidifier still works splendidly. Thanks, Alpine!

The product fit perfect, that's why we depend on accurate descriptions before buying

Fixed my problem and was easy to install

Works as intended for my Aprilaire 700 humidifier for our home's central hvac system. The OEM solenoid comes with a plastic filter/strainer on the input side of the valve. This replacement has some sort of metal screen there. I left the metal screen in place and will replace it with the plastic piece if it clogs up. I took away one star because the wires are noticeably shorter than the oem valve and it took some "customization" of my Aprilaire enclosure to make this work.

Using this and doing yourself is lot cheaper than having it replaced. It’s easy to do.

Great quality great price, works perfectly

This valve replaced the original without any modification, a perfect fit in my model 440. The valve appears to be well made, better than the original one with a plastic body which had cracked. It included a new compression ring and nut. The valve had a filter already installed and included a spare, a nice touch. Working good so far.

My new furnace was installed and it fried the humidifier valve because the voltage from the furnace was wrong. I had to drop the voltage from 110 volts down to 24 volts.It took me 10 minutes to remove the old solenoid valve and replace it with this one.It works like a dream. Great price too.

Arrived very quick. It is a must have to run your humidifier.

it meets my needs

it looks fine.Time will tell reliability

it works