Conventional tank type water heaters heat cold water via a simple heating element and then store the heated water in a large insulated tank. In addition to heating the water for storage, a traditional tank must constantly reheat water to keep it at a steady temperature, usually between 120 to 140 degrees Fahrenheit. This means that while you’re sleeping, at work, or away, your tank type water heater is burning energy. This is a very inefficient way to heat and store energy. A tankless water heater, on the other hand, only heats the water you need, resulting in much more efficiency.
There are two typical tankless water heater types, electric and gas water heaters. Electric tankless water heaters heat cold water via an electric element as it passes through the unit. Similarly, gas tankless water heaters heat incoming water via a gas burner as it enters the gas-fired unit. They both have certain advantages. Gas tankless water heaters are often utilized for entire house applications, where as electric tankless water heaters are often utilized for point of use applications, such as lavatories or kitchens.
The following represents a very simple step by step explanation on how a gas tankless water heaters work. An electric tankless water heater works very similarly, but utilizes electric heating units (step 4) rather than a burner:
The specific output of a tankless water heater unit is an important factor when purchasing a tankless water heater. The output of a given tankless water heater is determined by its maximum flow rate. The maximum flow rate is measured when a desired temperature rise is met. Most tankless water heaters provide flow rates of approximately 2 – 6 gallons per minute. Most commonly, gas type tankless water heaters have superior flow rates when compared to their electric counterparts. As a result, gas-fired tankless water heaters are the most frequent choice when it comes to a whole house application.
When selecting a tankless water heater it’s important to determine your needs. Are you looking for a point of use set up? If so, an electric type tankless water heater might be the best fit. Do you need a hot water for the whole house? If that’s the case, you’ll probably need something that can provide a large enough flow rate to insure two simultaneous hot water draws. Let’s say a shower and washing machine running at the same time, for example. Most electric units just don’t have the flow rates to meet those needs. For those in need of even larger flow rates, multiple tankless units can be set up in parallel.