Think about the hot water use in your house before selecting an electric tankless water heater. Add up the number of sinks, showers and appliances that require hot water. This inventory will be important as you compare the capabilities of different tankless water heaters.
May The Flow Be With You
The flow rate, measured in gallons per minute (GPM), is a measure of how much hot water is delivered to the faucet. Most homes will only have one peak hot water event at time. These typically involve running a dishwasher or washing machine, but can include running two or more showers at a time.
Generally, an electric tankless water heater with a flow rate of 3.0 GPM will provide ample hot water in this situation. Lower flow rate tankless water heaters would be fine for a few sinks or a single appliance. Measuring the flow rate of your faucets and appliances will give you a good idea of your flow rate requirements.
By design, electric tankless water heaters must deliver a large amount of energy very quickly to heat water. This means you need to be aware of the electrical needs of the electric tankless hot water heater you are considering.
Most electric tankless water heaters require 240-volt electrical service and will require from one to three 60-amp circuits from your circuit breaker. Electric service availability (particularly at the circuit breaker) may influence which tankless hot water heater you choose.
A Little Help From The Pipe
The incoming water temperature has a major effect on the efficiency of an electric tankless water heater. If you live in a cold weather climate, a larger capacity tankless water heater will offset the cold incoming water. In warmer climates, a lower flow rated tankless water heater will be sufficient.