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  3. What does the term “temperature rise” mean?

What does the term “temperature rise” mean?

The difference between the incoming ground water temperature and the set temperature of the tankless unit. For example, if your tankless unit was set at 120°F and your incoming ground water temperature was 50°F your temperature rise would be 70°F (120-50=70). Temperature rise is used to determine BTU size of heater, when peak fixture demand is known. I.e. large temperature rise and high peak fixture demand requires a tankless heater with higher BTU input capacity.

BTU
British thermal unit, the amount of heat required to raise the temperature of 1 lb. of water 1°F

Fixture
A device that receives water from the water supply piping

Temperature Rise
The difference between the set temperature of the tankless heater and the ground water temperature (e.g. 120 Fahrenheit setting – 60 Fahrenheit ground water = 60 degree Fahrenheit rise.)

Updated on April 13, 2021

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