Control the hot water temperature at faucets and showers that don't have anti-scald valves by installing either a mixing valve or a point-of-use tempering valve.
Cut the copper pipes at your water heater and reroute them through a mixing valve. Install a temperature gauge in a tee fitting near the valve to set the output temperature.
Install a “point-of-use” tempering valve below the sink. Shut off the supply valves and disconnect the existing supply tubes. Add the tempering valve and two new supply tubes.
Turn on the hot water and adjust the tempering valve to obtain 104 degrees F. or less.
If your home is plumbed with copper pipe, you can install a mixing valve right at the water heater and set the maximum temperature to 104 degrees F. You may still get some temperature variations due to fast changes in water pressure (such as from a toilet or a washing machine), but there will be no chance of scalding.
But before you break into any pipes or buy a water heater mixing valve, ask your local building inspector if your code requires “point-of-use” tempering valves at each faucet. These valves may be cheaper than installing temperature-regulating faucets.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.