Hot Water Heater Timer Recommendations for Energy Savings
InspectAPedia® -
Water heater timers: how to choose and use a water heater timer to save energy
Guide to inspection of electric water heaters
Timers for electric water heaters
Timers for tankless electric water heaters
How long should the "off" time be on an electric water heater
for a timer to save energy
Comparing savings from water heater timers with other options
Questions & answers about how to install, set, use, and troubleshoot electric water heater timer controls
Guide to water heater timers for energy savings: this article explains how discuss the use of timers to control electric water heaters and tankless electric water heaters. This article contains links to in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity.
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.
Guide to Using Timers on Residential Hot Water Heaters
The sketch above shows the basic components of an electric water heater and is provided courtesy of Carson Dunlop.
This article contains links to in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity.
Also see Energy Efficient Water Heating, a US Department of Energy, a PDF file that provides tips on lowering your water heating bill.
The link to the original Q&A article in PDF form immediately below is followed by an expanded/updated online version of this article.
The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.
Water Heater Timers
Question:
Does it make sense to put a timer on an electric hot water tank to turn it off for most of the day if no one will be home?
How about using a timer on a tankless electric water heater if gas is not available? -- Bill Geary, Belfair WA
Answer:
Efficiency of Timers on Conventional Electric Water Heaters
According to Princeton Energy engineer Gautam Dutt, the idea of using a timer on an electric water heater will work fairly well if your daily hot water consumption is less than one water-tank load, or if the hot water heater will be shut off for several days at a time, such as over a long weekend.
For shorter time periods or for higher hot water consumption rates, in the 1980's Dutt thought that it would be more practical to insulate the water tank.
However modern hot water tanks come from the manufacturer with good insulation, and in some cases insulating a hot water heater tank may fail to follow the manufacturer's instructions, could void its warranty, or could make the water heater unsafe (if for example you covered the pressure-temperature relief valve). --DF
In the 1980's a typical stock electric water heater was about 73-percent efficient, including tank losses. If you included hot water delivery piping losses, the efficiency of the water heating system drops to about 60 percent. This is a good incentive to add insulation on your hot water piping, and it may help you decide on using a water heater timer too.
At WATER HEATER EFFICIENCY we provide a comparison of the efficiency of different types of water heaters.
What is the Energy Efficiency of Electric Tankless Water Heaters?
Dutt said that tankless electric hot water heaters work best if the hot water demands are low, and if points of hot water use are clustered in the building (as opposed to having the tankless water heater deliver hot water through long pipe runs to distant points of use from the heater itself).
Obviously this is easier to achieve in new construction than in a hot water heating retrofit.
We add that because tankless water heaters have zero or very low stand-by losses, there would be typically be no gain achieved by installing a timer on an electric tankless water heater. -- DF
Drawbacks of electric tankless hot water heating systems are that they draw high electrical current (amperage) and supply low hot water flow rates. This means that from a modest-sized tankless electric hot water heater system you can't shower and wash dishes at the same time, and low hot water-demand appliances are in order as well.
Consumer Reports points out that a tankless water heater may be efficient but not necessarily economical to operate. What they mean is that it is certainly efficient to avoid heating water when no one is using it. But if water usage is high, a high-BTU tankless water heater may consume more total energy than a large but more conventional oil or gas fired hot water tank and burner.
Sketch (above) of a point of use tankless water heater courtesy of Carson Dunlop. Our OPINION is that readers looking for plenty of hot water heated efficiently should also consider the heater we describe at Indirect-fired Water Heaters.
If your hot water is not working, check the water heater timer: Some electric water heaters are installed with a timer (photographs above) that saves electricity costs by turning off the heater during periods when no one will be using hot water. If a timer is installed for your heater, it might be in its "off" position. Instructions for setting the water heater timer are inside the timer cover.
WATER HEATER PROPERTIES discusses water heater types and their efficiencies; there we also note that using a water heater at a high duty cycle (such as heating a home) will shorten its life.
Also see Energy Efficient Water Heating, US Department of Energy, a PDF file that provides tips on lowering your water heating bill.
Questions & Answers regarding this article
Questions & answers about how to install, set, use, and troubleshoot electric water heater timer controls.
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American Council for an Energy Efficient Economy, American Council for an Energy-Efficient Economy,
529 14th Street N.W., Suite 600,
Washington, D.C. 20045-1000, (202) 507-4000
E-mail: aceeeinfo@aceee.org
E-mail: ACEEE_Publications@aceee.org - www.aceee.org/ - original source for comments in this article|:: http://www.aceee.org/Consumerguide/waterheating.htm
GAMA data base of water heater efficiencies: http://www.gamapower.org/water.php
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.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book 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. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
"Solar Water Heaters", U.S. Department of Energy article on solar domestic water heaters to generate domestic hot water in buildings, explains how solar water heaters work. Solar heat for swimming pools is also discussed.
Passive Solar Design Handbook Volume I, the Passive Solar Handbook Introduction to Passive Solar Concepts, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v1.pdf
Passive Solar Design Handbook Volume II, the Passive Solar Handbook Comprehensive Planning Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v2.pdf [This is a large PDF file that can take a while to load]
Passive Solar Handbook Volume III, the Passive Solar Handbook Programming Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v3.pdf
"Passive Solar Home Design", U.S. Department of Energy, describes using a home's windows, walls, and floors to collect and store solar energy for winter heating and also rejecting solar heat in warm weather.
"Solar Water Heaters", U.S. Department of Energy article on solar domestic water heaters to generate domestic hot water in buildings, explains how solar water heaters work. Solar heat for swimming pools is also discussed.
"Heat-Transfer Fluids for Solar Water Heating Systems", U.S. DOE, describes the types of fluids selected to transfer heat between the solar collector and the hot water in storage tanks in a building. These include air, water, water with glycol antifreeze mixtures (needed when using solar hot water systems in freezing climates), hydrocarbon oils, and refrigerants or silicones for heat transfer.
"Solar Water Heating System Freeze Protection", U.S. DOE,using antifreeze mixture in solar water heaters (or other freeze-resistant heat transfer fluids), as well as piping to permit draining the solar collector and piping system.
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