Tankless Water Heaters

Tankless water heaters heat tap water quickly, efficiently, and only as hot water is being requested. As a result, these systems are 24 to 34 percent more efficient than conventional, tank-based water heaters that heat a tank of water at all times — even while we sleep

Performance

Tankless water heaters are capable of heating water to high temperatures and are able to moderate the warmth of the water as needed. They are limited, however, in how much hot water they can generate at any given time. This is called the flow rate, and, depending on the model, usually ranges between two and seven gallons of hot water per minute. Therefore, before choosing a model, it is important to make sure the system’s flow rate matches your needs. As long as your hot water use does not exceed the flow rate, you won’t run out of hot water.

Types

Tankless water heaters are powered by either gas or electricity. Gas models are typically the more powerful of the two but, because of their need for a pilot light, are generally less energy efficient. Gas models, however, can be used either indoors or outdoors, whereas electric heaters must be placed inside. Both models are about the size of a briefcase.

Tankless water heaters can exist as a whole-house application or a single-point application model. True to their names, the whole-house versions provide hot water to an entire home and have greater power capacity, whereas single-point application units only heat the water of specific rooms, faucets, or appliances (for example, washing machines).

Costs

Conventional, tank-based water heaters usually cost between $200 and $700 for electric models, between $300 and $2,000 for gas models, and last eight to 10 years on average. In comparison, tankless water heaters cost closer to $300 to $800 for electric and $500 to $4,500 for gas. Tankless water heaters last two to three times longer and make up for the higher price with increased energy savings. The pay-back period varies significantly.

Brands

Many companies offer tankless water heaters.  The October 2008 issue of Consumer Reports includes a report ranking the models based on their performance and customer reviews. The following is a list of brands to consider:

•     Noritz America
  
•     Paloma Industries
  
•     Rinnai Corporation
  
•     Takagi Industrial Co. USA, Inc
  
•     Titan
  
•     Rheem
  
•     Eemax
  
•     Stiebel Eltron
  
•     Bosch
  
•     WaiWela

Additional information

One complaint about tankless water heaters is that without a specialized pump that recirculates the water, the cold water in the pipes must be pushed out (and down the drain) before the hot water arrives. Not all tankless water heaters need these pumps, but if they do, they can cost up to $400, in addition to the cost of the water heater.

Also, note that if you live in a cold area, the system will use more energy to heat incoming water to hot temperatures than if you live in a moderate climate, so you will likely require a heater with greater power capacity.