AprilAire 400M Whole-House Humidifier, Manual Water Saver Furnace Humidifier, Large Capacity Whole-House Humidifier for Homes up to 5,000 Sq. Ft., White

This humidifier works really well. Installation was straight forward and easy. It takes a little time to do it right. The day I installed it, the humidity in the house was 20% and miserable. (Had been that low for a month) By the evening the humidity was low 30% and the house felt much better. By the end of the second day the humidity was up to 40% (my set point) and has been there for 2 months. Sleeping better, breathing better and dry skin is gone. This humidifier does exactly what they say it will do,

I'm very happy with this humidifier. (I replaced an old drum style humidifier that always had water in the reservoir that got green etc. Wish I had replaced it earlier.) My HVAC contractor recommended the 400 because it uses a lot less water. Also, he recommended that I install it on my return duct, which I did. I also hooked it up to the hot water supply for maximum humidity.I did the entire install. The wiring was a bit confusing but there a many YouTube videos on line. I also called customer service and they were excellent.

Easy to install, didn’t have to use transformer as 24ac HUM connection on AC.Humidity is sitting at 39 after 1 week of use.Like the water saver feature

I recently installed the AprilAire 400M unit to one of the heaters in my home. The incredible difficulty that I had was determining what electrical wires went where, if it could be hooked up to a Nest thermostat, and if so, how. I am writing this review in hopes of making the experience less difficult for someone else by sharing what I have found to be correct and true, allowing the unit to function as it should. I have only recently installed the AprilAire unit, so I cannot comment on the performance as of yet. Let me start by saying that I am a fairly "mechanical" type person and have a decent understanding of electrical and HVAC units - but I am in no means an expert at either. The AprilAire packaged items that you will receive include: The main humidifier, the humidistat (either manual or digital), a saddle valve for attaching to copper water line, and a 24v transformer. I will discuss each item, and how they apply and are to be used. The kit does not come with: screws to mount any of the items, the needed water line to run from your home line to the humidifier, the ductwork needed to run from the humidifier to the other plenum (other duct side of unit), the needed 6" collar to insert into the other side of plenum, the additional 18ga wire you will need to run from the humidifier to the heater unit, or any sealant/tape. The unit also comes with a fairly simple, yet very basic and lacking set of instructions for install. The install of the humidifier unit is pretty straight forward - you mark out the size of the "template" which is actually the full size instruction sheet, and then cut this opening out where you will be putting the humidifier. As per AprilAire, it does not matter if this is on the supply or return side of the heater unit, but then the actual "bypass" (the new ductwork you will buy, along with new collar) will be installed on the other side of the unit (either supply side or return side - opposite of where you put the humidifier). You can mark out the size of the hole to cut for the bypass line by tracing the outside of the new collar that you bought. The saddle valve will be attached to your existing water line in your home. Then you will add the new section of water line that you bought to that valve, and run it to the water supply on the side of the humidifier. I do not prefer saddle valves as they are prone to leak, so I bought a new Sharkbite "T" connector with a shutoff valve on it and used this. It was also easier as my home has PEX water lines, and not copper. However, I did use a new copper 1/4" line to run from the "T" to the humidifier as copper is less prone to leaks or punctures than using a plastic tube. My humidifier is the 400 which does NOT require hot water to be fed, but I did notice in some units that it says you must tap into the HOT water side of your homes line. Okay - that is the easy part, and the less confusing part. The confusing part is when you get to the electrical - and what gets hooked up to what, and if it is actually needed or not. My HVAC units are fairly new, being only 5 yrs old, and I have a NEST 3rd Gen thermostat on the main floor. The confusing thing for me was that the inside of my heater unit did not have a "control board", so there was no obvious "C" (common) wire connection to tap in to. I also became aware that my Nest thermostat could run the new humidifier, without any need for the supplied Humidistat, or the 24V transformer, which made things a lot easier. I understand that this can be done with the Ecobee thermostat as well, but I am not familiar with them. To wire the humidifier unit up to my heater and thermostat all I had to do was the following: 1- Go to your Nest thermostat, pull the faceplate cover off and determine if you have extra wires in the back. If your home is somewhat newer, you will have 18/8 (18-gauge wire, with 8 individual wires inside) wire running from the thermostat to the heater unit. And if so, not all 8 wires are being used, and they likely just wrapped the extra 3 or so in the back that weren't being used. If there are extra wires - take one and plug it in to the * (star) position on the lower right side of the thermostat base until it clicks. Doesn't matter which color - but the black is commonly used for Humidifiers. If you do not have extra wires - you will have to run a single 18ga wires from the heater unit down to your thermostat to do this. Okay - Now go back to your heater unit - but don't open it up until you kill all the power to it - either by the shut-off switch on the side of it, or by going to your breaker box and shutting off all of the breakers to it. Once all power to the unit is killed - go ahead and open up the main access door. Find the area on your heater unit where all of the wires are coming in (usually a hole punched in the side or top). You will have large, thick black wires - which are the main power wires that run to the beakers, and there should also be 2 sets of smaller wires (1 set going down to the thermostat, and the other set going out to your AC unit outside). The set of wires going out to AC unit will only have 2 wires , and will be easy to differentiate from the 5-8 wires coming in from your thermostat. Once you find the wire group that runs to thermostat, locate the black wire (or whatever color you hooked up to the * on Nest) and tie/splice/connect a portion of the new wire you purchased to this wire. There are 2 wires on the side of the Humidifier that you need to tap in to - a yellow one and a white one. This black thermostat wire will tie in to the White wire on the side of humidifier. Just one more to go - tie/splice/connect another piece of the new wire you bought to the yellow wire coming off the side of the humidifier. This wire will connect to the "C" (or common) wire inside of your heater unit. Some units will have a "control board" where you will see the other thermostat wires attached too, and labeled as R,C,G,W,Y - etc. You want to tap in to the "C" wire or attach it to the screw or clip. If you followed these steps - You DO NOT have to use the supplied humidistat, OR the supplied 24v transformer. The Nest unit operates off 24V, and a transformer will already be inline, and another would just be redundant. However, if your heater is older, or you are not sure if you have a 24v transformer/system - test the wiring first to make sure or you will blow something, and it won't be good. Finally - now that you have all of the AprilAire unit hooked up - you can close up and seal the heater unit as you are done in there. Now go back down to the Nest thermostat - you need to tell the thermostat that you installed new equipment, and what to do with it. Go to Settings - then to Equipment. It will pull up a screen that shows all of the wires connected to the thermostat. Turn the dial till you get to the * on the bottom right and hit enter. Nest will then ask you what type of equipment this is. Select Humidifier, then Humidifier+heat, then No fan. This will run the humidifier when the heat comes on only. If you go back out of settings, and then back into Equipment, your humidifier should now show up. Select your Humidifier - and now you can set the Humidity level that you want it to run at. Nest runs displays "droplets" as the levels or percentages. All the way to the left is 0% and all the way to the right is 100%. You can also go into the app on your phone now and much more easily adjust and fine tune the humidity level/output. Thats it. You're done. Of course, if you don't have a Nest or Ecobee - you can simply use the supplied Humidistat and transformer for control of the Humidifier. Just simply mount the humidistat, and now the white wire from the Humidifier that ran to your black Nest wire, will run in to the Humidistat and then another wire out from the Humidistat out to the transformer. The transformer will need to be powered by an outside power source that is 120vac and is separate from your blower motor.

I had an old, old, old unit attached to the furnace when I bought the house. This thing was terrible. I think it was actually more of a breeding ground for germs and bacteria than a humidifier. That old piece of junk was cracked on the bottom and I said enough of this thing. It was started to leak and the water inlet/float was not working correctly and would continuously allow water to continue to let water in and not stop. I had tried to make adjustments and finally said enough. I searched and searched for a replacement and this one came with good reviews and people seem to like it. Since I already had one attached to the furnace I just had to modify the size of the hole for the new unit and connect all of the ductwork and electrical. I knew it was working quite well because I set the dial to what the old one was set at and the house seemed incredibly damp. The windows were fogging up. I live in Michigan and in the winter time the bay window will fog up when the humidity is high. I kept baking it off until the ridiculous amount of condensation was no longer present. So it works and the humidity controller is functioning properly. I also have a humidistat to check humidity in the house but I just rely on the old eye test. Overall...... Excellent unit at a great price.

There was a review below that helped massively for the wiring. I work in the gas utility industry so I had a bit of knowledge but honestly it was an easy install. Great unit work fabulous. There was things included in my unit that said wasn’t included so I had to return some to the store but I’m not complaining haha

Amazing addition to any furnace in Canada's colder weather. This works as advertised and does not use as much water as many of the others as there is no waste.

could be more discription of wiring. wasted a lot of time with wiring . The problem was that the supplied 24 volt transformer was not working, this was annoying. unit worked fine after getting a working transformercannot rate comfort as it has only been working for 1 day

Read instructions. It will go easier. Works great. Love it. 👍👍👍👍

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