AprilAire 400M Whole-House Humidifier + Manual Control

Coming off an older unit that basically dumped gallons of water down the drain daily during heating season, this unit is a world of difference. I haven’t gotten my next water bill bill yet, but doing some monitoring myself, I’m very confident that it’s going to be significant lower than winter seasons past. My bills run in 3 month cycles, and I will tell you heating season water bills are my worst, by far, even with all the extra showering and watering during summer months. The old units just dump unused water straight down the floor drain. I am handy and installed the unit myself. I only had to enlargen my cutout an inch or so, so no big deal. I eliminated the saddle valve from the original unit and sweated a copper coupling in its place. I installed a 3/4” Sharkbite valve a little closer to the unit and shortened the existing 1/4” supply copper tube. The unit even came with a spare water pad, so I find that to be a bonus. Installation only took me about 2 hours, only because I have extremely limited space behind my furnace where I was patching up the old saddle valve setup. Very pleased with the quality of this unit, and it also raised my humidity level about 15 percentage points within a few hours. That is coming off my old system which I had turned off since last year. Great produ

Previously, I had another manual model (500m) that drained continuously. Although it was rated for a home of 3,000 sq. Feet, it never was able to keep humidity levels of our 1,600 SQ. ft. Home at a preferred 45% RH. Instead, at most if might hit 38%. On top of this, it was dumping into the furnace condensation pump adding additional electrical bills and wear and tear with a potential for flooding since it continuously wasted water.I thought “upgrading” this to a 400m which covers 4,000 sq. Ft. and doesn’t drain might be the perfect solution. One less thing to go wrong and it might actually cover more of the house, right? Well, as I found out I was very wrong. I ended up enlarging the opening slightly over the 300m which I had expected. The bypass still lined up perfectly. However, I noticed that the house was now hovering around 27% humidity vs. 38% with the previous model. Taking the cover off, I noticed that there was water in the tray, but the panel filter itself wasn’t wicking up water. At first I thought there might be something wrong with the solenoid but I bypassed the wiring and the solenoid worked as expected. I ended up trying the wiring bypass to ignore the switch but now this just turns it into a larger 300m with the water drainage issue again. Also, water had overflowed at night—apparently the overflow drainage hole is smaller than the 300m so you have to carefully take your t valve and turn it way way down. I also highly recommend that you DO NOT use the supplied Saddle Valves as they leak all of the time. Most HVAC and plumbers will tell you that.So I tired to figure out a way to fix it and had contacted Aprilaire. A rep told me that this unit should not be run when the fan is on but only when the call to heat is initiated. Also, the fan shouldn’t be run which I find problematic as I use this for whole house air purification and to balance out the rooms. Secondly, he recommended hot water to it if possible which I already had installed on a recirculating line. Third, he mentioned that the bottom third of the filter was to remain wet at all times but this wasn’t happening. All that being followed, I’m at a loss for the unit.I can’t return this item because I’d have a gaping hole in my return duct. I can’t go back to the previous unit because it was smaller. Calling a HVAC contractor won’t do anything other than run me a bill because it’s installed correctly. The main issue is that the water panels are simply inefficient at wicking up water according to their claims. Also, the SQ. Footage they claim is assuming you have a new leak-proof construction home which most people don’t.As a workaround, I decided to cut a strip off of an older clean t-shirt and make sure it dips into the well and acts as a more through wick. I didn’t cover the whole panel as we still need the air flowing through it. My humidity has gone back up. My only concern is that the humidity might shot too high. At which point I suppose I could turn down my humidification settings on my Ecobee 3 or cut smaller strips if necessary. I plan on replacing or washing these strips frequently although I suspect they’ll absorb some of the antibacterial properties of the honeycomb panel. If I had to make a recommendation to the company, they need to find a better material for these panels.

Well designed and very effective performance. Needed to humidify when using our wood furnace and have had trouble finding any furnace-mount humidifier that would fit the only flat vertical area available on my ductwork. I couldn't find any reference on the company website or in reviews for required opening dimensions for this unit so I emailed the company late Friday evening and got a company response Sunday: H-12.5", W- 10", perfect for my situation.To install this you need to be pretty precise cutting into existing furnace ductwork. I used a jig saw to cut the rough opening and an angle grinder to finish the opening to final, plumb dimensions, then mounted the humidifier. You will also need to tap into a nearby cold or hot waterline with the self-taping needle valve supplied, or better, with a quarter-turn ball valve that you buy separately, which I did. Self-taping needle valves present several long-term maintenance problems in my experience. I purchased 10' 1/4" copper tubing and some extra brass compression fittings from HD, along with 10 ft. of flexible duct for the bypass, a 6' elbow and 6" flange for connecting the flex duct to the return plenum. The last thing you need to do is mount and wire in the 24V transformer into your wood furnace wiring and run some low-voltage wire to the humidifier. The wiring, plumbing and ductwork can each present installation challenges and take much longer than you imagine, particularly if you don't have a well equipped workshop and abroad selection of tools and basic plumbing and electrical supplies. I do have those things and budgeted a full day once I had everything I thought I would need, but it actually took me parts of 4 days, but at 68 I'm always slower than I expect. It has turned much colder, 15 deg this morning and windy, and the humidifier works really well, supplied with cold water in this installation. As advertised, the unit needs no drain but there is a fitting for one just to play it safe, which I am using to protect other furnace components. Good luck!

Instructions clear and easy to understand.

Replaced a regular electronic bypass with this unit and love that it doesn’t waste gallons and gallons of water down the drain!

In the winter our forced air furnace made our home so dry with the humidity level always in the single digits. Now with this unit I set it to be at a consistent 35%. No more dry skin for my wife and I or our 2 dogs. My dogs also shed far less and I don’t shock them anymore when I try to pet them.I’m kind of handy but I was always intimidated about installing this myself. Had I known it was so easy, I would have done it a long time ago.

Very happy with the product.

Aprilaire 400 works great with no drain.