Aprilaire 600M Whole-House Humidifier with Manual Control

Aprilaire 600M Humidifier and 3rd gen Nest Thermostat InstallThis is a fairly easy project, but there are many steps involved, and a lot of info to gather. I am writing this so you should have everything you need in this review to do the project. There are many wiring diagrams you may stumble upon. I have included the 2 best ones I have found. I only had 4 wires in the bundle run to my thermostat. I had AC, heat, and fan. I ran 18/8 wire so I would have 8 wires total. Then I could have 1 for common so that the nest would always be powered, and * for the humidifier, 2 more than my original 4 bringing the total to 6 wires, leaving 2 extra to futureproof. The 18/8 wire is more expensive per foot, but I only needed 30’ (bought locally). 18/7 comes in a 50’ roll, so the price was the same. Just measure how much you need, then add about 5-10’ to be safe. Some systems have dual fan speeds and such, which are many times not used, but the nest may be able to use them. Find your furnace manual online or look at the wiring diagram(s) inside the furnace access covers if there are any. If you have to run more wire, plug the wires in to the nest setup website, so you can use the same colored wires they did to minimize confusion. If you have extra unused wires, put both ends in a wire nut to be safe. I first wired everything without the included transformer and was using the furnace’s built in transformer, see attached wiring diagram. When I first turned everything on, it all seemed to work fine for about 5 seconds, then smoke blew out the side of the solenoid valve! I turned the heat way down and let the furnace finish its cycle and the solenoid valve got pretty hot so there was definitely a short. Amazon sent me a new solenoid valve so no big deal there. The reason for using the included transformer with the relay is to isolate the humidifier solenoid from the furnace and Nest, and this experience proved to me why that would be important! The downside to having a dedicated transformer to the humidifier is that it is always on, and drawing extremely minimal power, but its still power. You may be able to wire the 110V side of the transformer to the extra contacts on a 6AZU3 relay so that there is no such loss, or maybe the relay can control the 110V side and then 24V side always stays connected using the 6AZU2 relay, do some research and try it!I mounted the relay and extra transformer inside the furnace next to the control board.I took the solenoid apart, and it looks like the windings shorted out to the outside case. I’m not sure if it would cause more harm than good, but you could take apart the solenoid before powering it up to check that nothing is shorting with the outer casing, maybe add some electrical tape around the windings, but you risk damaging the wires that power the solenoid. If you need/want to take it apart, take off the nut on the end, then the small rubber grommet. Now the electrical part of this should slide off the shaft. The slotted part (for a flathead screwdriver) does not need to be taken off, that just holds the water valve in. Then push the yellow wires in to the housing while carefully working the windings out of the housing.Keep in mind that the Nest does not have a built in table to decide what humidity you need for a given outside temperature, as described in the Aprilaire operating manual. I have read that the Ecobee thermostats have this kind of table built in. There is a website mynestreports that has some custom settings you can use, including this very table, for the Nest. His values are exactly what is in the Aprilaire owners manual for the M versions. You just log in with your Nest login, and check the boxes and it works. Many complain about this, so I wish Nest would add this feature to the software! Also, the Nest and the app, configured in Hum. will allow you to adjust the Rh more precisely while the Hum. + heat option shows you rain drops on a slider scale. The rain drops do correspond to a 5% increment, as verified on mynestreports.com. So if you set the Aprilaire up using hot water, everything else the same, and you could control the fan, you could use the Hum. setting and see the Rh. Minor point.I’ve run the humidifier now for about a month, and after the house absorbed the moisture, the setup holds my set humidity well. I added 5% to the humidity numbers in mynestreports for everything below 40%, so 40 % is repeated. This is because my heater runs a long time in the morning to warm the house back up from being turned down at night. The day temps are higher, so I wouldn’t get as much humidity as I could because the morning heat run would cut the humidifier early for the current morning temp. Basically, on mynestreports you can see how long the heater has been on, and how long the humidifier has been on. If the times are the same the humidifier is on whenever you are heating and you are getting as much humidity as you can using cold water. Just keep an eye on the windows for any condensation.Keep in mind that the advertised size of house that the Aprilaire 500 and 600’s can humidify is probably based on using hot water to evaporate more water. I have an on demand heater, so I did not want to run the water heater all the time. I therefore bought the 600M so that cold water would work better. It seems overkill, but the prices are very comparable especially through Amazon Warehouse. Also, the yellow plastic orifice in the discharge tube is the same for the 500 and 600, so you are using the same amount of water either way, and electrically they are identical.Also, the 400 requires you to change filters twice per season, but it is more efficient with the water. You will need a drain of some kind for the 500 and 600. My furnace had a small pump on the side to catch water from the furnace and AC, so I just put the drain in the 3rd hole, works fine.I used a duct for a rectangular register, and cut it and bent it with some snips and sheet metal pliers, then sealed the edges with foil tape. If you look closely at one of the pictures, you can see that I left the corner of the duct intact, and its more of a vane now. I just used some pliers and sheet metal pliers to bend the corner into a flat plate, this keeps the duct more rigid. Your installation may be different, but try to minimize how long of ducting you need and turns.I almost had to move/modify my furnace vents, but there was enough clearance, keep this in mind for your installation.Also, consider using a level when cutting your opening and installing the unit, the water distributes in a tray on top, and you want it distributing evenly.There is a “Nest Pro Installation Guide” available. There are some wiring diagrams in there, which can be useful, but not complete or straightforward. The diagrams I have included should work for the nest. They recommend a different relay, but they do the same thing.You will need to go into the pro settings, just hit continue and ok etc. Use the dial to move down to the *. Select it, and set it up for being a humidifier. In the pro install guide, it says “Pro Setup will show an Activate setting to specify whether heat needs to be activated for humidification to turn on. Bypass humidifiers should use the Hum. + heat option while steam, independent, or on-demand humidifiers should use the Hum. only option.” So in this case that means the humidifier will only turn on when the heat and fan is on. You can set this up to run the humidifier with the fan, and no heat, but you will need to plump the humidifier to hot water then, see the Aprilaire manual on their website.The 600M came with a saddle valve (I have read these are not the best), the manual humidistat, evaporation panel and all internals, but no wiring, ducting, or plumbing. Keep in mind the warranty is voided if you install it and are not a professional. The only part I could see breaking is the solenoid valve, and those are ~$30.Here are some links to useful tools you may not have. The non-contact voltage tester is pretty useful with the built in flashlight. The tin snips are hardened so they should last a long time. The pex tool was the cheapest I found, the smallest, which could come in handy in tight places and for storing it, and it comes with a tubing cutter and test gauge. I just cut my pex tube, put in a T, then a fitting with a shutoff to go to the humidifier. Klein Tools NCVT-3 Non-Contact Voltage Tester with Flashlight IWISS Pex Pipe Crimping Tool kit for 3/8",1/2",3/4",1" Copper Ring with Free Gauge&Pex Pipe Cutter -Meet ASTM F1807 for Sharkbite,Watts,Apollo-Light and Portable MIDWEST Aviation Snip - Left Cut Offset Stainless Steel Cutting Shears with Forged Blade & KUSH'N-POWER Comfort Grips - MWT-SS6510L MIDWEST Aviation Snip - Right Cut Offset Stainless Steel Cutting Shears with Forged Blade & KUSH'N-POWER Comfort Grips - MWT-SS6510R Parts list:- Aprilaire humidifier of choice- Ducts and or vents- Sheet metal screws- Duct/foil tape- Thermostat wire, suggest 18/7 or 18/8 (Only if you don’t have enough wires)- Crimp on electrical connectors- Electrical tapePlumbing (depending on the plumbing in your house):- Pex pipe, fittings (T, shutoff, union, etc), crimp collars- Copper pipe, fittings, solder, flux paste- PVC pipe, PVC fittings, PVC solvent/glue- ¼” copper tube will be needed for any setup, that is what goes into the humidifierTool list:- Non-contact voltage tester- Voltmeter (I didn’t end up needing one, but could have)- Tin-snips, suggest R & L hand- Wire cutter/stripper- Other common tools etc. Klein Tools NCVT-3 Non-Contact Voltage Tester with FlashlightIWISS Pex Pipe Crimping Tool kit for 3/8",1/2",3/4",1" Copper Ring with Free Gauge&Pex Pipe Cutter -Meet ASTM F1807 for Sharkbite,Watts,Apollo-Light and PortableMIDWEST Aviation Snip - Left Cut Offset Stainless Steel Cutting Shears with Forged Blade & KUSH'N-POWER Comfort Grips - MWT-SS6510LMIDWEST Aviation Snip - Right Cut Offset Stainless Steel Cutting Shears with Forged Blade & KUSH'N-POWER Comfort Grips - MWT-SS6510R

everything comes with it, easy to install

Like the headline says, shoulda installed one years ago. I live in North Central Washington, where the air is really dry, and winter is cold enough that my heat pump runs roughly 12 hours a day. Last year the average humidity level in my house was in the mid-twenty percent. Dry, itchy skin was the norm (and I'm aging, so the scratching is beginning to be an issue. Sigh.). I installed this a month ago, and just started using it 5 days ago. It's taken a few days, but the humidity level in my 4,000 square foot home is now at 38%, and still climbing. I'm more comfortable, my skin feels better, and I think I'll be able to lower the temperature soon (currently I run 70° F daytime). Fantastic!Install was easy for me, my water heater is right next to my air handler. I had to install it in the less-desirable configuration, humidifier on the return air, due to a lack of space. Still works grand, but would probably be more efficient on the supply side. I have a Nest thermostat, so didn't use the included controller. Didn't need the included transformer, either (and you won't either if you have a Nest with a C wire). Took me maybe an hour total to install, even having to cut a circular hole in a cramped space (used the adhesive style duct connector rather than a standard starting collar. No need for a perfectly round hole that way) Oh, and skip the included saddle valve if you can. I spent the extra few bucks and used a Sharkbite ball valve. Easy peasy.In other words, just buy it. You'll be glad you did!

We bought this to replace a retro Aprilaire that was probably 50 years old. The older unit needed work, and I was prepared to do that until I saw how reasonably priced a new unit was. We opted for this bypass version, whereas the older model we had was fan powered. Honestly, I am glad we went with the bypass version. Yes, it took a little more work and materials to run the bypass duct, but an incredible amount of air circulates through the unit. I am under the impression that this has to be more airflow that a powered unit.Within 30 minutes of the first time we had this installed and our windows were dripping wet due to the luscious humidity, and so was our basement...There are some things that could be better about the unit, but some minor modification can fix most of the worries. At the end of the feed tube is a little yellow orifice. This meters the flow of water so that an appropriate amount runs through the water panel. It also turns the feed tube into a super soaker. Water sprays out of the orifice with enough force to launch clearly across my basement (30 ft), and what happens inside the unit is splatter all over the place, which collects on the housing and runs down around the water panel before leaking out of the seam in the cover (not through the drain). This created quite the mess in short order in our basement... luckily it is currently unfinished so I just squeegeed up the water and put a fan on it to dry overnight. Due to the design being reversible, there was probably no good way to make it so that if spray hit the housing it would funnel back into the distribution tray so it could route through the drain tube. A covered distribution tray would help... not sure if that would create mold. I did a pretty easy fix that should be worry free - simply move the orifice to the solenoid end of the feed tube. This way it dribbles out of the unobstructed end vs a 300mph needle jet.We have this hooked up to our Nest thermostat, which was super straightforward. No need to use the included transformer or humidistat, and no need to purchase a relay. As long as you have the Nest powered by 24VAC through the common wire, create a circuit by routing a wire from the * terminal on the nest to the common terminal in your furnace. I love being able to adjust the humidity level and temperature from one place. I now feel like we have complete control of our climate in our house.All in all, I definitely recommend this unit, with a couple watchouts so you don't flood your basement.

Recently installed this so I cannot really say how much I like it yet long term but so far it’s working perfect. As a lot of other reviewers mentioned it’s really easy to install this and that was my experience as well. The directions are clear and there are a ton of great videos out there to help you along. It seems very well designed and it went in without a hitch. I chose the manual model since I have it connected to an ecobee premium thermostat. Hopefully it will provide years and years of trouble free humidity So far so good!