Will one unit be sufficient for my home or business?
Yes, unless you have a large house in which several people typically use hot water at the same time (multiple showers), Stiebel Eltron Tempra Series Tankless Water Heaters (Tempra 15 and larger models) will provide your entire home with an endless supply of hot water.
Normally, we find that people are not concerned with multiple users of hot water at the same time, because water pressure issues already prohibit that type of usage. Most people are concerned with the "one shower after another" situation. You will never run out of hot water again!
In warmer climates, you can run up to 7 gallons per minute (far more than enough for more than 2 showers at a time) with an appropriately sized electric tankless water heater. In colder climates, a maximum flow rate of 3 to 3.5 gallons per minute is more realistic, and only one major hot water demand at a time should be expected. Please review our Model Selector for more details.
For very demanding applications, you can use more than one tankless water heater in series or parallel or use a tankless water heater as a booster to a conventional tank-type heater.