Honeywell AM-1 Series Thermostatic Mixing Valves. ( water heater tempering )
Many plumbing codes require a tempering valve to prevent scalding if you have a tub that people bath in. A tempering valve takes the cold water and mixes it with hot water and dials it down to a suitable temperature.
Some adjust between 70 F and 120 F
And you can also get one that does 70 F to 145 F
Raising the water in the tank to 140 F helps to prevent the growth of Legionella bacteria.
• Allows homeowners to store water at 140 F and
higher to prevent legionella growth, but receive
safe, comfortable 120 F water at sinks, shower
• Designed to increase the amount of usable hot
water by up to 50 percent