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Picture of How to save water with your humidifier.
A whole-house humidifier can make you more comfortable in winter, and it can help you be a bit greener by making your house feel warmer, which lets you turn down the heat. But most humidifiers waste an enormous amount of water. Here's how to reduce that waste.
 
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Step 1: Recycle instead of dump

Picture of Recycle instead of dump
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I recently installed a whole-house humidifier on my home's heater. I bought a Honeywell because it was rated Energy Star. Apparently Energy Star doesn't apply to water use, though, because for every gallon it puts into the air, it dumps at least 5 gallons down the drain. It works by trickling water through a filter and blowing air over the filter. Any water that isn't picked up by the air blowing past just goes down the drain.

I decided to recirculate the water back into the humidifier instead of dumping it.

Start with two 5-gallon buckets. Tape the buckets together, bottom-to-bottom, and drill a pilot hole through the bottoms of both buckets. You might also want to remove the handle on the bottom bucket because it tends to get in the way.

Now pull the buckets apart and use the pilot hole to drill a 1" hole in the top bucket and a 2" hole in the bottom bucket. Also drill another 1" hole in the side of the bottom bucket about 5" from the bottom. Check out pictures in the next steps first and you will see why these holes go where they do.

Step 2: Parts you need

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You will need a pump, a toilet fill valve and hose, and some plumbing parts. I used a $10 aquarium pump from Harbor Freight. The pump has a 1/2" outlet so I needed a few adapters to get it into the 3/16" hose on the humidifier. You will probably also need a copper tee and parts to extend a water line to near the bucket. I'm not very good at soldering copper so I went from the tee to a PVC union and used glued PVC the rest of the way. Put a toilet supply valve at the end and this will have the 3/8" compression fitting for your toilet supply hose.

You probably want the type of toilet fill valve that has the float riding on the valve itself, rather than the old-fashioned type with the stalk and balloon float. The old kind is what I have and you'll see what I had to do to make it fit.

The hard part for me was figuring out all the connections and going from pipe to hose to smaller hose. It took a few trips to the hardware store.

Step 3: Putting it all together

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Remember those holes you drilled in the buckets? Use the 1" hole in the top bucket to install the toilet fill valve. It will stick out through the bottom of the bucket and into the bottom bucket, whose only purpose in life is to get the top bucket off the floor. Thread the supply line through the hole in the side of the bottom bucket and connect to the valve. Connect the other end to your water supply, just as if you were hooking up a new toilet. Try not to use this as a toilet, though.

Connect the pump to the humidifier (I pulled the hose off the humidifier's water supply solenoid and connected it to a barbed fitting on the pump hose).

Wire the pump to the heater. You probably want to use the heater's "EAC" connections, which provide 110VAC while the heater fan is running (presumably for an Electronic Air Cleaner?). It's best if you can wire through a switch so that you can turn off the pump in summer or when you're not running the humidifier.

Finally, drop a bleach toilet cleaning tablet into the bucket and put a cover on the bucket. This water is going to be going into your air supply so we don't want to be giving anybody Legionnaire's Disease.

Final note: if I hadn't already paid for and installed the humidifier, I would have searched for a water-saving humidifier instead of going to all this trouble. This only makes sense if you're trying to improve an old humidifier but better ones are available now.
RTurnock4 months ago

I have thought of this but decided no to because of the risk of mold, fungus etc. building up in the recycles water. I also find it impossible to set a tap "just right" even with the little pin hole inserts they provide it's too much waste. My conclusion is to cycle the valve, i.e. when the humidity control is asking for water I plan to put a timer relay between it and valve so I can set what percentage of the time the valve is open.

Hello. Please tell, what was the result? Did you try the water valve on the main device, to curb water usage/wastage? Did you continue using the bucket collector?

chartle3 years ago
Much simpler solution.

Find the valve that feeds your humidifier. When the furnace is running and warmed up. Turn down the valve until just a trickle of water comes out the bottom and into whatever drains your system.

Double check every once and a while.

Much less chance of getting Legionnaire's Disease.
Kezz6 years ago
Its a great water saving idea. However because this device is going to be the tank for the humidifier - I recommend that you use a non-toxic agent to avoid bacterial growth - like Iodine Vinegar and bicarb Natural oils (I am thinking eucalypt but I dont know enough about thier anti bacterial properties) etc.... Or putting a water filter cartridge/ scrubber in-line with your pump - you don't want to be breathing ammonia in the air. Especially if its vaporised
nate121 Kezz6 years ago
tea tree extract will kill germs
quigs999 (author) 6 years ago
Good idea. The toilet tablet contains bleach, not ammonia, and I'm sure the concentration of chlorine is pretty low, but I still don't really want to be breathing it.
I mean use the water from your humidifier to fill your toilet tank, and flush your toilet, instead of storing it where it'll grow bacteria.
BigNateMI6 years ago
Why don't you feed the water into another system like the toilet flush water, or a garden or lawn irrigation system. Then it's not wasted, and not recirculated.
steveharr6 years ago
You'll want to be very organised to remember to add some kind of water treatment at regular intervals. The very reason your unit doesn't recycle its water is as you mentioned, Legionnaire's Disease. Ummmm I wonder why the manufacturer does not make it recycle water????
mowdish6 years ago
I'm flabbergasted that a company would produce a humidifier that sent unevaporated water down the drain. It seems so obvious to me that II would have torn my house apart looking for a leaking pipe, before it would occur to me that the humidifier didn't recirculate it's water. Good for you for fixing it.
PKM mowdish6 years ago
I would guess that that is because recirculating water can keep the water hanging around long enough for nasties to grow in it. Perhaps a periodic flush feature that stops recirculating for long enough to drain the water would be a good idea? Anyway, good detective work on finding out just how bad your old humidifier was.
mowdish PKM6 years ago
I don't know. The easiest way to prevent nasties is to keep the water moving. And quigs999's set up is a simple, effective and very obvious way to do that. In the Southwestern U.S., where the air is generally dry and hot, it is common to use evaporative coolers in the summer. These work by blowing hot dry air over wet filters. As the water evaporates, it cools the air. This sounds just like quigs999's humidifier. Having years of experience with evaporative coolers, I never had problems with stagnating water. Of course, this humidifier isn't operating in a desert in the middle of the summer. But simply using a small reservoir would insure that the water doesn't sit for long. Unless someone can explain how a winter humidifier is the equivalent of a petri dish, I'm going to stick to my flabbergasted ruling.
I've got an evaporating cooler and it recirculates. If the water is not used in 72 hours it dumps it
richms6 years ago
The new water coming in will be treated by the city supply, so should take care of anything in the storage bucket, its a small amount and quickly turned over so shouldnt get anything growing in it other then when left idle for a while, so I would just make it a habit to drain the system when going away for a while. If you were to put the origional valve on the supply to the toilet valve you could just shut the power off to it and leave the humidifier running till its dry assuming the pump is ok with running dry (not sure on those small ones)
lemonie6 years ago
You'll need to keep treating the water in here, but well worth it for the water that isn't wasted! L