 Tankless Water Heater Life Expectancy, Uses & Applications
Demand Water Heaters or Instantaneous Water Heaters or
Endless Hot Water Systems
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What is the life expectancy of a tankless water heater, & what are the types & applications of tankless water heaters - demand sater 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
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, see How to Speed Up Delivery of Hot Water.
- 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] - see SOLAR HOT WATER HEATERS
Whole house tankless water heater
- 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 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. Particlarly 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.
Frequently Asked Questions (FAQs)
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- [1] Thanks to Mark Cramer, Tampa Florida, for assistance in technical review of the "Critical Defects"
section and for the photograph of the deteriorating gray Owens Corning flex duct in a hot attic. Mr. Cramer is a Florida home inspector and
home inspection educator.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
- [3] HREF="http://www.consumerreports.org/">Consumer Reports offers an article on the efficiency versus the economy of tankless water heaters - see http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm
- [4] Bosch Tankless Water Heaters - http://www.boschhotwater.com/
- [4a] Bosch, "Instrucciones de instalacion y manejo, Calentador de agua instantaneo, Confort / Confort S 6BP / 6BP n 10BP / 10BP N 13BP / 13BP N"
Robert Bosch, S. de R.L. de C.V., Calle Robert Bosch 405, Zona Industrial, Toluca, Edo de Mexico CP 50070, website: www.bosch.com.mx, Tel: 800-11-26724 (2010)
- [5] Chromolite Tankless Water Heaters
- [6] Bradford White Everhot Tankless Water Heaters - Bradford White offers this step by step hot water retrofit installation file (large, slow PDF) - www.bradfordwhite.com
- [7] Eemax Tankless Water Heaters - http://www.eemaxinc.com/
- [8] Noritz Tankless Water Heaters - http://www.noritz.com/
- [9] Rheem Tankless Water Heaters - http://www.rheemtankless.com/content/
- [10] Rinnai Tankless Water Heaters - http://www.rinnai.us/tankless-water-heaters/
- [11] Stiebel Eltron Tankless Water Heaters - http://www.stiebel-eltron-usa.com/
- [12] Takagi USA Tankless Water Heaters - http://www.takagi.com/
- [13] Titan Tankless Water Heaters - http://www.titanheater.com/
- [14] U.S. Department of Energy on Tankless Water Heaters - http://apps1.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=12820
- [15] "Tankless or Demand Type Water Heaters,"
U.S. Department of Energy, retrieved 10/14/2012, original source: http://energy.gov/energysaver/articles/tankless-or-demand-type-water-heaters [Copy on file as Tankless_Water Heaters_DOE..pdf]
- [16] Solar Water Heating, U.S. Department of Energy, retrieved 10/14/2012, original source: http://energy.gov/node/367417
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
- Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
er- Plumbing Diagnosis & Repair: Water supply, drainage, septic systems, water testing, water contamination, defective plumbing materials & products.
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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