Have you thought about buying a new hot water heater yet? Unlike the other necessary appliances in one’s home, a new water heater is not usually on the top of one’s to-buy list until his current one breaks. Then, in a state of panic (and with dreams of a hot shower), the homeowner doesn’t take the time to shop around to find the unit best suited for his needs. This is unfortunate, however, because the different types of water heaters vary substantially.
In selecting the hot water heater that will best suit your needs, it is necessary to understand the different types, and to balance the pros and cons of each. The following is a brief summary of two of the most common types of hot water heaters on the market today: the conventional storage tank water heater and the tankless water heater (also known as the “demand water heater” and the “instantaneous water heater”). Your plumber will be able to provide more information about these, and other less common types of hot water heaters, and to assist you in purchasing the hot water heater that best suits your household’s needs.
Conventional Storage Tank Water Heaters
The most common type of hot water heater in the United States today is the tall, familiar, cylindrical white tank that is fueled by natural gas, oil, propane or electricity, otherwise known as a conventional storage tank water heater. This type of heater works by heating large quantities of water in advance of use, and then releasing the water when the tap is turned on. More specifically, cold water flows into a large insulated tank, is heated by a burner or coil in the tank (utilizing electricity, gas or oil), and is then kept hot in the tank until needed. When the tap is opened, hot water flows through the pipes and cold water enters the tank, restarting the process. The benefit of this type of heater is that the tank (which typically stores 40 to 80 gallons of water) is always full, and hot water is available around-the-clock.
The downside of a conventional storage tank water heater, however, is that it wastes a huge amount of energy (known as “standby heat loss”) in maintaining hot water even when it’s not needed, increasing one’s energy bills unnecessarily.
Tankless Water Heaters
One method of completely eliminating standby heat loss, and reducing energy consumption by up to 30 percent, is to purchase a tankless water heater.
As its name implies, a tankless water heater heats water directly, without utilizing a storage tank. Rather, when the hot water tap is turned on, cold water travels through a pipe into the heating unit and is heated by either a gas burner or an electric element. As a result, the tankless water heater delivers a constant supply of hot water, but only when needed. This results in a significant reduction in energy costs.
However, as any licensed plumber will tell you, there are a few downsides.
First, a tankless water heater generally costs more to purchase and install than a conventional storage tank water heater. However, over time, the energy savings mentioned above can be enormous. Moreover, the life expectancy of a tankless water heater is generally 20 years, as opposed to 13 years for a conventional storage water heater.
Second, a tankless water heater has a limited flow rate, meaning that the amount of hot water that can be produced at one time is limited. More specifically, tankless water heaters generally provide hot water at a rate of two to five gallons (7.6 to 15.2 liters) per minute, with gas-fired heaters producing higher flow rates than electric ones. While the standard flow rate might be sufficient for a house that does not use hot water at more than one location at the same time, in large households even the largest, gas-fired model may not produce enough hot water. A solution to this problem is to install two or more tankless water heaters.
Third, a tankless water heater takes longer to produce hot water than the conventional storage tank variety since it doesn’t start heating the water until the faucet is turned on. Thus, each time the tap is turned on the user needs to wait about 20 seconds for the water to become hot. While waiting, about a gallon of water is wasted.
Depending on your household’s needs and your budget, one type of heater may be more suitable than the other. When determining what to buy it is a very good idea to sit down with your plumber and to discuss your particular situation.