#1 Home Improvement Retailer

Internet #202771119

Model #12HF

Store SO SKU #1000801311

Whole House Furnace Mount Flow Through Humidifier

Apply Now
Save up to $100 on your qualifying purchase.
Apply for a Home Depot Consumer Card
  • Create a healthier environment with a whole house humidifier
  • Product sold without installation or permitting
  • Equipment should be sized/installed by a qualified professional
  • View More Details
How to Get It

Frequently Bought Together


Product Overview

Create a healthier environment and Increase the comfort of your entire home by installing the 12HF whole house furnace-mounted flow through humidifier. Having the proper amount of humidity in your home can help reduce respiratory infections, control static electricity, prevent house plants from wilting, and stop wood from drying out and cracking. You may also save money on your utility bill, as you can lower your thermostat and feel just as comfortable since humidified air feels warmer.
  • Uses up to 80% less water than other brands of whole house flow through humidifiers which will save you money on water and sewer charges from your municipality
  • Output of up to 13 Gal. per day for well insulated homes up to 3,000 sq. ft.
  • Lightweight housing design makes the humidifier easy to install on either the warm air supply or return air duct of any forced-air furnace
  • Everything needed for most typical installations is included
  • Evaporator pad is enclosed in plastic frame that ensures water flows through proper path for evaporation and makes it easy to replace
  • 24 VAC transformer simplifies installation as it plugs into a standard outlet and no hardwiring is required
  • Designed for use with all forced-air heating applications
  • Cut-out areas required for installation:humidifier housing: 8-1/4 in. H x 9-1/4 in. W
  • By-pass duct: 6 in. Dia
  • Humidistat: 3-1/2 in. H x 2-3/8 in. W
  • Equipment should be sized, selected and installed by a qualified professional to ensure proper installation, safe operation, adherence to federal, state and local codes and for valid warranty; see installation guide for more details
  • Recommended for professional purchase only
  • Click here for more information on HVAC Installation
  • Click here for more information on Electronic Recycling Programs

Additional Resources

From the Manufacturer

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.



Maximum coverage area (sq. ft.)
Maximum Room Size (cu. ft.)
Product Depth (in.)
Product Height (in.)
Product Width (in.)


Air Treatment Product Type
Whole House Humidifier
Color Family
Control Type
Floor drain required
Humidifier Features
Automatic Moisture Control,Drain Hose Included,Installation Kit Included
Humidifier style
Bypass flow-through
Humidifier Tank Capacity (Gallons)
Included Items
Drain Hose,Installation Kit
Installation kit included
Number of Air Filters Included
Pack Size
Product Weight (lb.)
Room Size (sq. ft.)
Large (Greater than 1000 sq. ft.)
Voltage (volts)
Water Filter Replacement Model#

Warranty / Certifications

Certifications and Listings
UL Listed
Manufacturer Warranty
1 Year Limited Parts Warranty, Lifetime Warranty on Frame and Cover

Questions & Answers

Typical questions asked about products:

  • Is the product durable?
  • Is the product easy to use?
  • What are the dimensions of the product?

Customer Reviews

  • 4
    out of 85 reviews
  • 88%recommend this product
Filter by:
Showing 1-10 of 85 reviews
I installed this unit in a hall way utility closet thus a tight fit. The air return is under a wo...
I installed this unit in a hall way utility closet thus a tight fit. The air return is under a wood deck so the flex duct needs to be longer than the supplied one. A hole was cut to accommodate the duct. The drain was routed to a sewer vent PVC vent pipe under the deck. A 1/2 inch brass nipple to threaded fitting was installed with a bit of thread paste after drilling a hole in PVC. I really don't like the pipe piercing fittings. I soldered a TEE in a cold water pipe with a ball valve. Now the system can be securely shut off and less risk of leakage. The controller system is inadequate as whether it is set on HIGH or LOW heat, the humidifier will not match the start or end of the heat cycle. Thus there is lots of water wastage and less humidifying. The solution is to activate the humidifier with the thermostat call for heat or manual fan run. I bought a pair of relays for $15 (mxuteuk 2pcs JQX-13FL AC 24V Coil 8 Pin 10A DPDT LED Indicator Electromagnetic Power Relay, with Base, with DIN Rail Slotted Aluminum). Now I can run the humidifier by turning on manual fan or it runs with auto heat cycle and matches the cycle exactly. All the wiring comes off the thermostat control terminals in the heater, these are low voltage terminals. Don't make my mistake of using the HUM terminal which is 120 volt, that fried the controller and was $47 to replace. We started with indoor humidity of 23%, With running on heat cycle only we reached 28%. By running on auto fan for several hours the humidity reached 30%. I hope to get to 35% in a few more days. I'll try to include pictures and wiring diagram with this review. During the summer the humidifier won't run with COOL cycle as the relays aren't connected to that terminal.
    • Recommended
    1 found this review helpful
    This humidifier consistently maintains 40-42% humidity on a gas furnace, with outside temps about...
    This humidifier consistently maintains 40-42% humidity on a gas furnace, with outside temps about 40 degrees. Install was not hard even with cutting into the ductwork. The 2 screws for the diffuser were the wrong size (#8 vs. #6) but had some on hand. The wire from the controller to the valve needs to be longer. It's only long enough if your supply and return access is on the same side of the furnace. Last, I would recommend a stiffer 6" flex duct. The 3' piece that was included wasn't long enough for mine, and the one I bought was sturdy enough not to need any added support or clamps. Overall I'm happy with the 12HF humidifier. I dropped the thermostat 2 degrees since it actually feels warmer in the house and the nose/sinuses feel better.
      • Recommended
      5 found this review helpful
      Inadequate for desired humidity
      Product was received as advertised and installed per directions with no issues. I am going on my second season of use however I have been unable to achieve a desireable humidity level of 39-40%. I have a 1600 sq ft home and with outdoor temperature in the upper teens to mid 20's the indoor humidity level will not exceed 33%. I believe this unit is helping with humidity but the unit capacity is over rated and did not meet my expectations.
        2 found this review helpful
        Took a while to install plus a couple hours troubleshooting... make sure your water pressure is ...
        Took a while to install plus a couple hours troubleshooting... make sure your water pressure is not too high as the relay can't open the valve, the directions say psi over 90 is too much I think it's a lower threshold, I switched to the saddle valve and it seemed to work better. All in all it seems to be working well, humidity is definitely up in the house.
        • Verified Purchase
        • Recommended
        3 found this review helpful
        Replaced a 20 year old foam roller unit. This thing really does the job. Easy to install. I re...
        Replaced a 20 year old foam roller unit. This thing really does the job. Easy to install. I really like the water saving feature. You can hear the valve cycle on and off due to the provided timer relay (make sure to install it as shown between the valve and ac voltage supply). Note: use the 24vac from your furnace. The provided 24vac plug in supply has too few amps to properly energize the valve at times without buzzing, which is valve solenoid chatter. Finding a larger 24vac transformer is easy if your furnace cannot supply it.
        • Verified Purchase
        • Recommended
        6 found this review helpful
        Purchased this item online local Home Depot does not carry...
        Purchased this item online local Home Depot does not carry in stock.Installed this humidifier myself in about 3 hours following directions.I have 40 years in multiple trades and would not recommend self install unless mechanically inclined. Works great with adjustable humidistat.Great Product.
        • Verified Purchase
        6 found this review helpful
        Thank you, Timely delivery, easy assembly and mounting instructions.
        Thank you, Timely delivery, easy assembly and mounting instructions.
        • Verified Purchase
        • Recommended
        2 found this review helpful
        100% satisfied
        Performs exactly as advertised, very quiet and does a great job moisturizing the air in my little 672 sq. ft. home. No significant increase in my water usage either.
        • DIY
        • Verified Purchase
        • Recommended
        5 found this review helpful
        Works Great but the installation may need enhancements
        This humidifier would be rated 5 stars for an application that requires no adjustments to the supplied installation plans. My basic, forced air furnace is installed so that only one side of each vertical plenum is accessible. It was necessary to install the humidifier on the wide side of the hot air plenum and then use rigid 6” round duct work to feed the unit’s output into the horizontal cold air plenum. This unit is designed to fit the flexible duct that comes with it. The output port of the unit is much smaller than the female side of a 6” round duct so an adapter had to be fabricated. By hammering out the crimps of the male side of a 6” elbow, it then fit nice and snug onto the supplied plastic starter collar. During testing, the pulse module never came on in the normal setting. The “LO” setting worked but would continue to pulse water for 15 minutes after the furnace turned off. An outlet was installed on the side of the furnace for the unit’s AC adapter. This outlet was wired to toggle on and off with the furnace fan. I was then able to leave the pulse module setting on low with the unit automatically shutting down when the furnace fan turned off. The unit works perfectly now, but I feel installation enhancements such as this would be beyond the ability of many home owners. The media pads are not carried at Home Depot and must be ordered on-line. One pad should last an entire heating season. In summary, this type of humidifier, with a flow through water system, is the only kind to use. I’ve had plenty of bad experiences with the rotating drum, water bath, calcium clogged nightmare types to never go back.
        • DIY
        • Recommended
        22 found this review helpful
        Great Product. I mounted it to the flex duct return.
        This is a great product. I read the reviews online and discovered the Honeywell model has issues, so I went with Hamilton. Very pleased and zero regrets. I have a 1,600 sq. ft. house and this unit can make the windows drip with condensation (I actually have to turn it down). No moving parts (except the water solenoid), no slimy drum to clean out, and best of all no humidifiers to refill. See the pictures, attached. The directions say it can be mounted to either the return or supply ducts at the furnace. I have a flex duct return, so I wanted the main body of the humidifier mounted to the solid surface of the supply duct. The directions did not describe this scenario, so I improvised. I hope the attached pictures and drawings help someone else in the same boat I was. I did have to install a 110VAC outlet for the power. However, I already had an existing drain (for AC condensation), for the drain tube. The unit works beautifully and no more dry skin. Great job Hamilton!!!
        • DIY
        • Recommended
        27 found this review helpful
        Showing 1-10 of 85 reviews