Today I finished a project that was pretty easy after I figured out the mechanics involved. One regulation in our state for family child care is that the water temperature in sinks/baths/etc cannot exceed 120 degrees. Most homes, including mine, have the water heater set at a higher temp (around 140F). I didn't want to reduce the temperature for the entire house.
After some research, trial and error, and a completely unhelpful and degrading manager at a big box store that starts with L and rhymes with "toes," I was able to put in a system that reliably lowers the hot water temperature on the sink.
My Supplies (not pictured: a wrench, plumbing tape)
Two Ice Maker Connector Reinforced PVC, 1/4" Compression inlet & outlet, 12" long
Four Compression Adapter, 3/8" Fem C x 1/4" OD
One T Adapter, 3/8" x 3/8"
One Sloan Mixing Valve for Lavatory Faucet, Mix-60-A
First I turned off the hot and cold water underneath the sink, then I unscrewed the hot and cold hose from the supply valves. The T Adapter screwed directly onto the cold supply. I used plumbers tape at each joint to help prevent leaking.
Next, I added an adapter each end of each connector hose. You will have to remove the compression bolt; it isn't needed for this project. Screw one hose onto the hot water supply line. Screw the other hose onto the "T" part of the T Adapter on the cold water supply.
Now you are ready for the mixing valve! Fun! Screw the cold hose onto the "cold" side of the valve and the hot hose onto the "hot" side of the valve. (Super tricky, right?) Double check that the screws are tight, there are TWO at each connection.
Last step is to connect the hot water supply line to the mixing valve and the cold water supply line to the T adapter. I cleared out the space below where I worked and put a paper towel underneath before testing it. This was 1) so there wouldn't be as huge of a mess if there was a leak 2) I could tell if there was a small leak by looking at the paper. GUESS WHAT? There was no leak! Woo!
You can adjust the mixing valve to give the desired temperature you want for the hot side of your faucet. Mine is set pretty low - just warm enough to be comfortable washing a face. If for some reason you do need hot water in the sink, then you can move the valve over to stop the cold water from mixing.
Tota cost for this project was around $60. If I had taken time to find hoses that had the end pieces I needed I think I could have saved a little more, but overall I'm happy with the outcome.