Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: What is the best or should I hook up a hot water or cold water supply?
Document: The 800 is the best humidification product I've ever installed. Period. Outperforms anything else on the market. For the negative reviewers: constant service lights usually mean that your water continuity is too low. Read the instructions, they'll detail how to fix in 30 seconds with common table salt. As for supply hose leaks, this is also documented in the instructions. Run the supply tube vertically for the recommended length and the clamp won't slip on earlier models.
I went through two Honeywell Truesteam units before switching to the Aprilaire 800. The design of the Aprilaire is superior to the design of the Honeywell. It's really night and day. The Honeywell ran incredibly hot, and the circuitry is immediately above where the water boils (i.e., in a very hot place), and the parts are not near the quality of the Apriliare.
Save yourself many dollars and hours of frustration. I have tried 2 other whole-house humidifiers and 3 portable Humidifiers and this one is the best;- After frustrations with those previous models, this Aprilaire Model 800 was recommended to me by a friend in the HVAC business.- If you have hard water (test it), you want this unit. You just replace the canister and done.
That's it. Or, just order the upgraded muffler style clamp that comes with newer model.Otherwise, always use 240 volt, never feed from hot water line, and install a small expansion tank line-of-sight from the solenoid, and you're in great shape. Read and follow the instructions, people!
It did raise the humidity but not nearly enough. Granted, my home is not well insulated. Also you have to constantly fill it with water, every other day, in my case and this thing holds like 5 gallons.Best of Luck!!! !
I'm a retired chief engineer. I've installed and did maintenance on commercial types of these humidifiers back in the day. This home system is by far the best out of all of them. I had a Honeywell system I installed in my home 2 years ago. Couldn't keep up or maintain a constant humidity. I even wired in a control relay to override the the main fan to start when furnace would shut down on via T-Stat.
Excellent design, kudos to the engineers whom designed it! The controller even overrides the main fan, normally controlled by T-Stat, to keep humidity constant. Everything is dependent on how you wire the humidifier controller in to do the things you need to keep your % RH within guidelines. Even comes with real outside air temp. charts to manually set it as not to over humidify your house during extremely cold outside air temperatures. I was truly impressed by this product and would recommend it for any residential type application.
I had one of these installed along with our Water Furnace geothermal system about 4 years ago. It made a tremendous difference in the comfort of our home - no more static electricity or dry sinuses. I am just now replacing the canister, but our well water has very little particulates so other users experience will differ I'm sure.
I happen to have a water softener so this wasn't an issue with me, but I point it out because the Aprilaire is well designed even in this respect. If you have hard water you will replace the inner cannister more, but your unit will work well because the water will boil more efficiently.I should also note that my unit is a remote installation. It is installed in my linen closet about 6 feet away from my furnace.
12% more humidity (40% is ideal) than Honeywell, in my experience. I have a little humidistat I use to gauge its effectiveness.- If you have hard water, I suggest getting a filter otherwise expect to replace this up to 2 times a winter. Its your water, not the unit.- When it is time to replace the canister you can clean it with some CLR (soak overnight) and it will likely last a few more weeks.
Answer: I don't have the installation instructions with me right now but I'm pretty sure they want it hooked up to the COLD water supply. It sometimes adds water to cool off the water in the system before it auto-drains. Mine is hooked to the cold water and it works great.