thermostatic mixing valves

tim smith_2

You got me thinking now, I am trying to remember the calculation. I know that at 120 degree hot with 105 mix out and 45 entering cold the percentage is about 80% hot. But there is a mathematical formula. If it pops in my braing I will post.

Oly

HOW CAN I DETERMINE HOW MUCH I CAN INCREASE MY WATER HEATER CAPACITY(DUMP LOAD)WITH THE USE OF A THERMOSTATIC MIXING VALVE? FOR EXAMPLE: 46 GALLON INDIRECT HOT WATER HEATER WITH A SETPOINT = 120 DEGREES F. VS. A MIXED SUPPLY =120 DEGREES F. WITH A SETPOINT = 140 DEGREES F. I WAS HOPING FOR SPECIFICS. ENGINEERING DATA OR SOME MATH FORMULA WOULD BE REALLY NICE. THANKYOU.

Mr. Bill

Water Heater capacity

The answer is it depends on things like recovery rates. However lets assume you are just storing water in the tank and not replenishing the energy or introducing cold water into the tank as its drawn off.

If your tank holds 46 gallons, you store it at 120 deg, and you want 120 deg. then you obviously have 46 gallons.

If you store it at at 140 deg but still want 120 deg. water you have to mix it with cold water. If the cold water is at 60 you would mix it with 27 gallons of cold, therefore your total available water at 120 would be 71 gallons.