Honeywell AM-1 Thermostatic Mixing Valves. ( water heater tempering )

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.



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• Allows homeowners to store water at 140 F and
higher to prevent legionella growth, but receive
safe, comfortable 120 F water at sinks, shower
or tub
• Designed to increase the amount of usable hot
water by up to 50 percent

Installing the AM-1







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With a recirc pump and a tempering valve, you will also need an aquastat to prevent the temperatures from climbing. Without an aquastat, the entire hot line, including the return line will climb in temperature to as high as what the water heater has been set to. With the aquastat, once the return line come back warm, it turns off the pump, preventing temperature overrun.



Grundfos makes this clip-on aquastat that fits onto the 1/2" return line.

Honeywell AMX300 Tempering Valve Kit for water heaters



Installed on a gas water heater.

Here is a smaller unit located in the bathroom, under a lav cabinet for the garden tub.