Rinnai: V53e Flow Verses Temperature Rise

Rinnai Tankless water heaters all have a wide BTU operating range and can provide precise hot water output over a substantial range of water flow rates.

This graph represents the relationship between water temperature rise (commonly know as ΔT) and maximum water flow rates. Assuming a given use temperature (120° for example) a tankless water heater can produce larger amounts of hot water with higher entering water temperatures. So if you are in a warmer climate area where the incoming water temperature is high, you can produce more hot water than the same model in more northern climates with colder incoming water temperature.

To determine the flow rate you may expect from a model of tankless water heater, measure your entering water temperature and apply it to the graph above. Subtract your entering water temperature from your desired use temperature to determine your temperature rise °F. Keep in mind that many water temperatures do vary widely as you go through the seasons: coldest entering water temperatures are typically in March or April, and warmest entering water temperatures are in October or November.