The basic principle for all tankless water heaters is the same and relatively simple.
Step 1:
The hot water faucet in your house is opened
Step 2:
Cold running water enters the tankless water heater
Step 3:
A water flow sensor in the tankless water heater detects the incoming water
Step 4:
A burner inside the water heater gets ignited
Step 5:
The water circulates through the heat exchanger inside the heater and gets heated immediately to the desired temperature
Step 6:
You get endless supply of hot water for your use
Time taken for steps 1 – 5: 2 Seconds