When you need hot water at the kitchen faucet, taking a shower, or washing dishes, cold water travels down a pipe and into the tankless water heater. Either an electric element or gas burner turns on, which heats the water instantly. The freshly heated water then travels down the pipe to the appliance or fixture where the hot water is needed. The supply and demand are immediate!

Tankless water heaters provide two to five gallons of hot water per minute.  Gas-fired models tend to have a higher flow rate than electric units. However, gas water heaters waste energy if the pilot light is constantly burning. When an intermittent ignition device (IID) is used, a spark ignition device eliminates the need for a standing pilot light. 

Tankless water heaters may not be able to keep up with multiple hot water needs occurring simultaneously. For example, taking a shower while using the dishwasher may push the tankless unit to its limits.

Homeowners can overcome the flow rate restrictions of demand water heaters by installing a whole-house unit and two or three point-of-use systems in your home. Kitchens are an excellent location for point-of-use water heaters.  They are small enough to fit under the sink and virtually eliminate the lag time for hot water. Another advantage to a point-of-use unit in the kitchen is freeing up the whole-house unit for hot water needs in the bathrooms and laundry room.