Tankless water heater (C) Daniel Friedman Pro PHCC Brand Tankless Water Heater Life Expectancy, Uses & Applications
Demand Water Heaters or Instantaneous Water Heaters or Endless Hot Water Systems

  • TANKLESS WATER HEATER LIFE & USES - CONTENTS: What are the suitable applications or uses of a tankless water heater, instantaneous water heater, point of use heater, endless water heater?
  • POST a QUESTION or READ FAQs about the best or most effective use of tankless water heaters, demand water heaters, & point of use water heaters & about tankless or demand water heater life & warranty periods

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What is the life expectancy of a tankless water heater, & what are the types & applications of tankless water heaters - demand water heaters or instantaneous water heaters.

This article describes typical and special applications of tankless or instantaneous water heaters in a variety of uses, and we distinguish among single or point of use demand water heaters, whole-building water heaters, when or how to use a gang of multiple instant water heaters, & the location of tankless water heaters outdoors vs. indoors.

Tankless or demand water heaters are also referred to as point-of-use water heaters when installed close to the fixtures or bath or kitchen where used.

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List of Typical Tankless Water Heater Applications

Tankless water heater (C) Carson Dunlop AssociatesArticle Contents

[Click to enlarge any image]

Thermostatic Hot Water Booster Applications

A single point of use tankless water heater is installed where a boost in hot water temperature is needed such as

  • Long pipe runs, slow hot water: In a building with long water piping runs the heat loss during delivery of hot water to distant fixtures as well as the delay in delivery of hot water are eliminated if a point of use tankless water heater is installed.

    If your concern is only the hot water delivery time,
  • High temperature applications: such as in restaurants, food processing, or other facilities where dishwashing requires a specific and high hot water temperature

Sketch of a point of use tankless water heater shown above was provided courtesy of Carson Dunlop Associates.

Single point of use tankless water heater

  • Limited hot water need: To support limited-requirement hot water flow requirements such as a low-usage restaurant bathroom
  • Intermittent hot water need: to support delivery of hot water that is only occasionally needed in a building, avoiding conventional water heater standby energy losses.
  • Home heating systems - water to air: Tankless water heaters may also be used to heat the home, either as part of a forced air combination system, or a radiant heating system.
  • Driveway ice melting: Demand water heaters are also used for heated driveways
  • Remote bathrooms or hot tubs [15]
  • Hot Water temperature booster
    • for appliances, such as dishwashers or clothes washers [15]
    • for a solar water heating system [15] -

Whole house tankless water heater

Cinsa Hidro Tec instant water heater (calentador) Mexico (C) DanieL Friedman

  • To address the limited hot water flow capacity of tankless hot water heaters in a building where lots of hot water is run at once people may install a large unit - which may not be the most efficient design if you do not usually run lots of hot water at many fixtures at once.

    If the required hot water volume is large (serving multiple apartments or laundry facilities at once, for example) no single tankless water heater is likely to be sufficient.

Our photo (left) illustrates a Cinsa Hidro Tec instant water heater (calentador) for sale in a Home Depot in Celaya, Mexico.

Multiple or ganged tankless water heaters

  • Install two or more individual and smaller tankless water heaters, possibly closer to their point of use - a more efficient design but possibly with a larger equipment and installation cost.

Indoor vs. Outdoor Tankless Water Heaters

Tankless water heaters are made in models designed to be installed outdoors, exposed to weather, or indoors in a protected area such as a basement or utility room or near a point of use.

Life Expectancy & Warranty Periods for Demand, Tankless, Instant & Point of Use Water Heaters

According to the U.S. DOE,

Most tankless water heaters have a life expectancy of more than 20 years. They also have easily replaceable parts that extend their life by many more years. In contrast, storage water heaters [water heaters that use a tank to store a reservoir of hot water] last 10–15 years.[15]

Note that this analysis does not include the cost of maintenance and repair for tankless water heaters that may experience extra costs especially in areas of water that is aggressive, corrosive, or high in mineral content.

Watch out: we are doubtful of this DOE claim. In fact tankless water heaters may be particularly vulnerable to installation errors, site conditions, weather exposure, or variations in gas or water pressure to the appliance. And in areas served by water high in mineral content the water heater's life may be short without proper maintenance. [Note that some tankless water heaters such as some more costly Bosch models, are designed to withstand hard water.]

The warranty period for the Bosch 13BP low-pressure LP gas instant water heater described at TANKLESS WATER HEATER INSTALLATION is 24 months from the date of first connection. [4a]

Causes of Loss of Warranty Coverage on Instant / Tankless / Point-of-Use water heaters

For just about any product, a close look at the terms and conditions of the product warranty also give us clues about the product's particular vulnerabilities or limitations. So it's always worth actually reading the warranty, including that for a tankless water heater.

Watch out: the Bosch warranty described above is voided if the water heater was not installed by an authorized service technician. The company provides telephone numbers of their authorized installer or service agency right on the packaging. Nevertheless, especially as heaters may be installed at buildings remote from larger cities where Bosch maintains a service staff, it is more likely that many installations will be installed by a local plumber or even a handyman - in essence meaning that the unit has no warranty whatsoever. [4a]

Other causes of loss of water heater warranty coverage include:

  • Damage to the device by work performed by unauthorized service workers
  • Connection of the device by unauthorized service workers
  • Operation or maintenance of the tankless heater under conditions not described by the manufacturer's installation instructions. Examples would be installing the heater outdoors in an area not protected from rain and wind
  • Damage to the device caused by its transport or by malicious vandals
  • Failure or damage caused by inadequate gas or water pressure to the device
  • Failure to perform recommended maintenance or installation of components that are not original or OEM.

Watch out: to assure that your instantaneous water heater continues to perform satisfactorily be sure to perform the maintenance recommended by the manufacturer. Particularly in areas where water is high in mineral content, de-scaling the water heater will be required at intervals determined by the amount of use the appliance receives.


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