WATER HEATER KNOWLEDGE
What Is Temperature Rise?
Temperature rise is the difference between incoming-water temperature and the desired outlet temperature. It is one of the two core values used to size a tankless water heater.
KEY POINTS
What to understand first
Simple subtraction
Outlet target minus inlet temperature equals required rise.
Climate matters
Ground-water temperature varies by region and season.
Higher rise needs more heat
The unit may support less flow when the water starts colder.
Use it with GPM
Rise alone does not describe household demand.
PLAIN-LANGUAGE GUIDE
Temperature rise connects climate to capacity
A heater in a cold-water region must add more heat to reach the same outlet setting than a heater receiving warmer inlet water. That difference affects how much flow the unit can support.
Use a realistic low seasonal inlet temperature rather than a best-case summer value.
WORKED METHOD
Calculate the required rise
Desired outlet temperature − incoming-water temperature = required temperature rise.
Pair the result with simultaneous GPM when reading the performance chart.
COMMON QUESTIONS
Frequently asked questions
Where do I find inlet-water temperature?
Ask the local water utility or a qualified installer for a realistic seasonal range.
Is a larger temperature rise better?
It is not a quality score; it is the amount of heating the system must provide.
Can I size from temperature rise alone?
No. You also need the simultaneous hot-water flow.
NEXT STEP
Read the Sizing Guide
Continue with the current NOVIEEX product information and model-specific requirements.