Tools and Materials Required
You need a 1.375-inch hole saw or step drill bit, adjustable wrench, basin wrench for tight under-sink access, Teflon tape, and a GFCI outlet tester. The K-6665 kit includes the tank assembly, faucet body, mounting hardware, and a 3/8-inch compression supply line. Kohler does not include the power cord -- you supply a standard 3-prong 18AWG cord rated for 15A, or have an electrician install a dedicated outlet near the tank position.
Step 1: Shut Off Water Supply and Drill the Sink Hole
Shut off the cold water supply valve under the sink. Drill a 1.375-inch (35mm) hole in the sink deck at the desired faucet location -- most homeowners place the dispenser faucet to the right of the main kitchen faucet. Use a slow drill speed on stainless steel sinks to avoid heat buildup. Smooth the hole edge with a file and apply silicone sealant around the faucet shank before inserting to prevent moisture intrusion into the cabinet.
Step 2: Mount the Faucet Body
Insert the faucet shank through the drilled hole. Slide the rubber gasket, then the mounting nut, onto the shank from below. Hand-tighten the mounting nut, then snug with a basin wrench -- do not overtighten on thin sink decks. The faucet outlet nozzle should clear the sink bowl by at least 4 inches to allow a cup to be placed underneath.
Step 3: Connect the Supply Line to the Tank
The K-6665 tank inlet accepts a 3/8-inch compression fitting. Wrap the tank inlet threads with two layers of Teflon tape. Connect the cold-water supply line from the shutoff valve to the tank inlet, then run the outlet tube from the tank to the faucet shank fitting. Hand-tighten all compression nuts, then snug with a wrench -- 1/4 turn past hand-tight is sufficient for compression fittings.
Step 4: Electrical Connection
The K-6665 draws 1500W at 120V (12.5A). Connect the power cord to the tank power terminals per the wiring diagram in installation document 1000005455. Plug into a GFCI outlet rated for 15A. Kohler strongly recommends a dedicated circuit to prevent nuisance tripping when the heating element cycles at full draw. Do not use an extension cord.
Step 5: Fill the Tank and Set Temperature
Turn the cold water supply on slowly and allow the tank to fill completely -- the tank is full when water flows steadily from the faucet nozzle with the lever held open. Once full, plug in the unit. The indicator light on the tank illuminates red during heating. First heat-up takes 15-20 minutes from cold. Set the thermostat dial (located on the tank body) to your desired output: 190F for tea, 200F for most instant cooking, 210F for blanching. Allow one full heat cycle before drawing water for consumption.
Troubleshooting: Faucet Drips or Tank Does Not Heat
A dripping faucet after installation usually indicates a loose faucet seat or debris on the O-ring -- remove and inspect the faucet body seat. If the tank does not heat, check the GFCI outlet reset button first; a nuisance trip is the most common cause. If the indicator light does not illuminate at all, verify the power cord connection at the tank terminals and confirm the outlet is live with a tester.