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AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
APPLIANCE DIAGNOSIS & REPAIR
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER, HEATER WATER FEEDER
CARBON MONOXIDE - CO
CHECK VALVES, WATER SUPPLY
CLOGGED SUPPLY PIPING
CROSS CONNECTIONS, PLUMBING
DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
FLOODED WATER HEATER REPAIR
FREEZE-PROOF A BUILDING
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HEATING COST SAVINGS METHODS
HOT WATER SUPPLY
HOT WATER IMPROVEMENTS
HOT WATER DELIVERY SPEED UP
HOT WATER EFFICIENCY IMPROVEMENT
HOT WATER PRESSURE EXPANSION RATE
HOT WATER PRESSURE LOSS
HOT WATER PROBLEM DIAGNOSIS
HOT WATER QUANTITY IMPROVEMENT
HYDROGEN SULFIDE GAS
INDIRECT FIRED WATER HEATERS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
NO HEAT - NO HOT WATER: HEATER DIAGNOSIS
NOISE, WATER HEATER
ODORS IN WATER
PIPING IN buildings, Clogs Leaks Types
RELIEF VALVE LEAKS
RELIEF VALVES - Water Heaters
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
TANKLESS WATER HEATERS
THERMAL EXPANSION of HOT WATER
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER HEATER ALTERNATIVES
WATER HEATER ANODES, DIP TUBES
WATER HEATER AIR INLET
WATER HEATER DEBRIS FLUSH
WATER HEATER DRAIN PROCEDURE
WATER HEATER EFFICIENCY
WATER HEATER FLUSH PROCEDURE
WATER HEATER NOISES
WATER HEATER PROBLEM DIAGNOSIS
WATER HEATER PROPERTIES
WATER HEATER SCALE
WATER HEATER SAFETY
WATER HEATERS for HOME HEATING USE?
WATER ODORS, CAUSE CURE
WATER PIPES, Clogs Leaks Types
WATER PRESSURE TOO HIGH: DANGERS
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
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.
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The sketch above shows the basic components of an electric water heater and is provided courtesy of Carson Dunlop Associates.
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.
Water Heater Timers
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
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 Associates. 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.
Readers should also see ALTERNATIVE HOT WATER SOURCES to distinguish among these types of hot water producing systems and see Electric Shower Heaters for a discussion of point of use heaters at shower heads.
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.
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