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AGE of WATER HEATERS
AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTIFREEZE for BOILERS
ANTI SCALD VALVES
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER, HEATER WATER FEEDER
CARBON MONOXIDE - CO
CHECK VALVES, WATER SUPPLY
CHEMICAL CONTAMINANTS in WATER
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CLOGGED SUPPLY PIPING
DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
FLOODED HEATING EQUIPMENT REPAIR
FLOODED WATER HEATER REPAIR
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HOT WATER SUPPLY
INDIRECT FIRED WATER HEATERS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
NO HEAT - NO HOT WATER: HEATER DIAGNOSIS
NOISE / SOUND DIAGNOSIS & CURE
NOISE CONTROL for HEATING SYSTEMS
NOISE, PLUMBING CHECKLIST
NOISE, WATER HEATER
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS IN WATER
PIPING IN buildings, Clogs Leaks Types
PLASTIC HEATER VENT
PLUMBING FIXTURES, KITCHEN, BATH
RELIEF VALVE LEAKS
RELIEF VALVES - Water Heaters
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
SOOT on OIL FIRED HEATING EQUIPMENT
SPILL SWITCHES - Flue Gas Detection
TANKLESS WATER HEATERS
Temperature Pressure Relief Valves - Water Heaters
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER CONTAMINANT LEVELS
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PIPES, Clogs Leaks Types
WATER PRESSURE & FLOW MEASUREMENT
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
Electric water heater controls, switches, & valves: This article describes the location, function, and troubleshooting of key controls and parts in electric hot water heater operation. Additional hidden controls on an electric hot water heater include its thermostat, high temperature cutout. We address these under-the-covers water heater controls beginning at Electric Water Heater Repair Guide. The articles at this website will answer most questions about electrical water heaters as well as many other building plumbing system inspection or defect topics.
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But watch out: sometimes an electric water heater is installed as an additional or backup hot water source, so you'll also want to see if you have other hot water heating equipment installed, such as a Tankless Coil for Hot Water.
Page top sketch is courtesy Carson Dunlop Associates. Reproduction of this web page electronically at other websites is prohibited. Also see TIMERS for ELECTRIC WATER HEATERS. If you cannot find information you need here or if you have comments, questions, suggestions for inspecting and diagnosing water heaters Contact Us
Carson Dunlop's sketch describes the sequence of operation that turns on the electric water heater's heating elements. If one of these heating elements has failed, the quantity or the temperature of hot water provided will be substantially reduced.
The dip tube on many water heaters functions as a sacrificial anode, as we show here. By constructing the dip tube of a metal which is more readily corroded than the steel of a steel hot water tank, the anode protects the hot water tank from early failure due to corrosion. Here Carson Dunlop's sketch shows the location of the sacrificial anode on an electric water heater.
If your water supply happens to be highly conductive or corrosive (see WATER TESTING GUIDE) then the dip tub/sacrificial anode in the water tank may indeed corrode away until it leaks (dropping the hot water temperature) or disappears entirely.
If your hot water smells like rotten eggs, you should definitely check the condition of the sacrificial anode on the hot water heater, no matter what kind of water tank you've got installed.
For details of how to inspect or replace the sacrificial anode or dip-tube on a water heater, please see Water Heater Anodes & Dip Tubes
Our photo (left) shows an unsafe extension tube on a water heater tank - the diameter of the extension(1/2") is less than the valve opening diameter (3/4").
This restriction could prevent proper valve operation should unsafe over pressure or over-temperature conditions occur at the water heater.
For details about water heater relief valves, please see Testing the Water Heater Temperature Pressure Relief Valve
Electric Water Heater Controls Behind the Removable Cover Panels on the Heater
Additional "hidden" controls on an electric hot water heater include its thermostat, high temperature cutout
We address these under-the-covers water heater controls, including the water heater temperature thermostat next, beginning at Electric Water Heater Repair Guide.
Frequently Asked Questions (FAQs) about the controls & switches found on electric water heaters
Question: hot water tank connected to my central heating system is used as an immersion heater
I have a hot water tank which is connected into my central heating system. In the summer
For a water heater that is used for both domestic hot water and heating, I'd suggest adding an automatic mixing valve right at the water heater hot water outlet line. The valve can be set to the desired domestic water temperature for washing and bathing; the valve works by mixing cold in with the outgoing hot.
Also take a look at ANTI SCALD VALVES
Question: water heater output is scalding even with our thermostats set to their lowest settings
With both thermastats set at the lowest setting the water is scalding hot. What is causing this? - Anon 8/12/11
Sounds like a bad thermostat control, or two of them. See
Question: lose pressure when turning on hot water
I have pressure inthe bath tub when the cold water is running, but lose some pressure when turning on the hot water - Aaron 3/12/12
Depending on several variables, particularly water piping layout and routing, in some buildings, turning on hot water will, by taking water off of a common cold supply line, cause a drop in cold pressure. Bosch warns of this problem in their installation instructions for their low pressure tankless water heaters, products sold currently mostly out of the U. S. but also sold in that country until about 2004.
Question: our water won't get hot
Water will not get hot when turn on hot water in house - Claude 11/29/12
Question: can I re-wire my water heater controls to convert from sequential to simultaneous operation?
I understand residential HW heaters are usually sequentially wired.
I agree in concept that one could perhaps change all of the electrical components on a given water heater: elements, controls, safety devices, thermostats &c. to convert from one type of water heater operation (sequential) to another (simultaneous) heater element operation, connecting the heater also to a properly wired and sized electrical circuit.
But frankly I would not take a chance on re-wiring a water heater to operate in any manner other than that specified by the manufacturer for that particular heater and model. Doing so could be unsafe. If you're admant about proceeding, start by giving the manufacturer of your heater a call, ask to speak with a technical engineer, and let us know what is her response.
Questions & answers or comments about the name, location, & function of all of the controls on an electric water heater.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.