Another important factor in choosing a heater is how you use hot water in your home.
Most American families use water during what we call “peak demand” periods. Scenarios such as average or larger families, frequent use of dishwashers, showers (especially multi-head showers and spray systems), hot tubs, normal to heavy use of washing machine, etc. With a heavy demand during a 60-90 minute period in the morning, followed another heavy-demand period in the evening. A tank type water heater is best-suited for this usage pattern, because of its ability to deliver a large volume of “stored” water and recover to heat additional water as needed.
“Heavy Peak Demand” Usage
The above pattern will most likely will create a demand that surpasses the capability of tankless. There may be hot water temperature fluctuations if more than one appliance is being used. The potential for a cold water sandwich increases, where “off and on” operations (e.g. back-to-back showers or washing dishes) create large slugs of cold water in the middle of the hot water delivery.
The following figures represent hot water demand usage where tankless is a good solution; demand does not have extreme fluctuations. These situations of occasional or steady usage normally within the output capability provided by tankless.
“Occasional Demand” Us
“Steady Stream” Usage