AprilAire 500M 12-gal Whole-House Small Bypass Evaporative Humidifier with Manual Control for up to 3 600 sq ft

Very pleased with this Whole-Home Humidifier I installed myself without any prior professional experience. That being said, I did spend about 5 hours researching installation techniques as the included directions are both difficult to make sense of as a layperson and also fail to reflect newer construction homes with furnace boards containing dedicated humidifier (labeled HUM) circuits. If you have a newer home, see photos and follow instruction. If your furnace's HUM circuit is 24VAC, then you won't need to use EITHER the included transformer or the recommended relay (an additional $35). When you wire the humidifier (using 18/2 thermostat wire), the humidifier only runs when the furnace fan/blower unit is running. When the home thermostat triggers the furnace to run a cycle, it will automatically trigger the humidifier to run along with the furnace. This is ESSENTIAL in saving TONS of money on unnecessary water usage. If you bought the MANUAL version humidifier (like me), then without paying additionally for the relay accessory the humidifier will run around the clock even when the furnace motor is off, essentially just draining your hot water down your floor drain. WIRING (with newer home construction or recently upgraded furnace) You'll first install get the entire unit installed after cutting LEVELED spaces into HVAC using included templates. It is essential that the unit is installed perfectly leveled to ensure balanced water flow throughout the humidifier unit filter. (1) Then, you'll run an 18/2 Thermostat Wire from the furnace circuit board into the vent where your humidifier unit is hooked up (you'll 18/2 wire will come in either a brown or gray sheath containing two wires; one white, and one red). Use conduit to protect wire if running between two vents, as shown in the attached photos. (2) With the 18/2 from the furnace circuit board to the humidifier, you'll tie-in the WHITE wire directly to one of the 2 yellow wires attached to the humidifier unit. The other end of the white wire will hook up to your HUM circuit on the furnace board using a CLAM adapter specified to your 18ga wire. (3) The red wire from the 18/2 running from the furnace circuit board to the humidifier unit will then tie-in to the screw on the near-side of the included thermostat (hung a minimum of 6" above your humidifier unit. The other end of the red wire will tie-in to your COMMON circuit on your furnace circuit board, labeled with a C. This is your 24VAC. There will likely be 1-2 cables already tied into your (C)Common from your homes thermostat and/or AC, so if you need to butterfly the wires to avoid crowding up the input then do so. (See included picture) (4) You'll then run a new, single red wire (pulled out of the brown/gray sheath) from the other screw point on the thermostat directly to the 2nd yellow wire on the thermostat unit. Simple as that! Hooking it up this way will ensure that your humidifier only pulls hot water when the furnace cycle is actively running after being triggered by your homes thermostat as it calls for more heat. TIPS from the PRO FORUMS I researched: -Avoid using the semi-rigid, extendable and flexible duct pipe when connecting the vent from your humidifier unit to the opposite return/flow vent (see pictures). PROS stated they never use this pipe for humidifiers because moisture can build up in the many grooves which can pose many problems down the road. RIGID Vents also allow for smoother airflow. -It was advised to NEVER use the included adapter for cutting into your copper piping to pull water if you are installing in a home without newer PEX Pipe. They stated these always fail over time and will begin to leak. If you have copper piping, you may need to solder in a T-Joint to run the 1/4" hot water line (this skillset is likely beyond the DIY'er). Bite the bullet and hire a pro, even if it is just for this purpose. -Use COPPER 1/4", and NOT plastic tubing when running from your hot water line (it is further advised to always run hot water through the humidifier) to your humidifier unit. -If you have PEX Pipe, working with Shark Bite joints is a breeze--just make sure you measure the depth of how far the pex pipe needs to be inserted into the Shark Bite valve to ensure proper seal. All in all, this was a lengthy install (took me about 6.5 hours with zero prior experience with HVAC) but the unit is running exactly as I had hoped. After one evening's cycle, humidity in the home is up 4% and I hope to be at the recommended 35% within 3-5 days (it was also recommended to NEVER put your humidifier thermostat above 35%, as this can result in excessive moisture build up in the home and lead to mold issues as well as harm any wood work/cabinets). I paid an additional $100 for materials, and saved myself the $300 installation charge for a pro (this was the low-end of estimates I received). The other perk of the self-install is forcing yourself to learn/understand the unit's functioning, which will assist with ongoing maintenance and troubleshooting if problems arise. Give it a go! Read more

The AprilAire Whole-House Humidifier has a sleek look and keeps my house comfortably humid at around 65-70% during the winter months. I have a 2,500 sq ft home, and this unit handles it effortlessly. Installation was simple and straightforward. I recommend this product to my friends all winter long! Read more

I installed a 500M on my furnace due to my house being very dry during harsh midwestern winters. It works perfectly keeping my home at a comfortable humidity 24/7. Pro's: 1. Does exactly what it should. keeps your home at a comfortable and healthy RH% that you set, and does it in a relatively quick amount of time. 2. Easy to use and replace the filter. Adjusting the the settings are as easy as turning a knob to the desired humidity, and it even guides you to suggested levels in relation to the outside temperature. Replacing the filter is quick and easy. Just open the cover, disconnect the water line, removed old and install new. 3. Cost. This unit does a lot for a little investment. Con's: 1. I personally didn't have any issues installing this unit in my house, but it is not something that everyone would want to take on without any HVAC experience. Understand that you will need to cut into your furnace ducting in multiple locations, and have the proper tools to do so, like tin snips, gloves, pliers, etc. You'll also have to do some basic wiring to hook up the humidistat to the furnace and the humidifier, and you'll likely need to be able to read and understand your furnace wiring diagram to know where to wire the unit properly to only work when the furnace is in it's heating mode. This would require some of the proper wire, an enclosed junction box of some kind (not required, but recommended), wire strippers, and hand tools. lastly, you'll need to get the excess water from the unit to an acceptable drain. I tied mine into my condensation trap with some 1/2" PVC and mounting straps. The unit does come with it's own drain hose, but I preferred to drain mine in a rigid line. You'll also have to supply the unit with water. This means tapping into an existing water line, or running a new one. If you think you can do all the above to install it yourself, it can be done with the proper tools and knowledge. If any one of those tasks seems like it might be out of your league (looking at you, electrical lol), then I would recommend hiring a professional to put it in. Overall: Works better than I expected, at a very good price. Easy to use and maintain. May want to hire a pro to install, but is possible to put in yourself. Read more

Fairly priced, moderately easy to install and effective for my 1500 sq foot house. The filter is easy to pop in and pop out for seasonal changing. There's not much cleaning required once up and running, a filter swap and perhaps a wipe down for any hard water stains and calcium buildup. Read more