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Schematic of a sacrificial anode on a hot water tank (C) Carson Dunlop AssociatesControls & Parts for Electric Hot Water Heaters Inspection, Diagnosis, & Repair

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.

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List of Electric Water Heater Controls & Operation

Sketch of electric water heater element operating details (C) Carson Dunlop AssociatesPage top sketch and the illustration at left are used with permission, courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Carson Dunlop Associates' 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.

Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank

Schematic of a sacrificial anode on a hot water tank (C) Carson Dunlop Associates

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 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.

See WATER TESTING GUIDE

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 ANODES & DIP TUBES on WATER HEATERS

Check the Hot Water Tank Temperature and Pressure Safety Relief Valve

Water heater temperature pressure relief valve (C) Daniel Friedman

Our photo 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.

Reader 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

Reply:

Sounds like a bad thermostat control, or two of them. See these diagnostic articles

Electric Water Heater Controls Behind the Removable Cover Panels on the Heater

Water heater thermostast and reset switch (C) Daniel FriedmanAdditional "hidden" controls on an electric hot water heater include its thermostat, high temperature cutout

Check these other hidden controls on an electric hot water heater

To adjust the temperature of your electric water heater or calorifier

see ELECTRIC HOT WATER TEMPERATURE CONTROL

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

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. Those are discussed separately

at TANKLESS COILS - home

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.

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 want to set up my ordinary 240vac, two-heater, water heater for maximum economy. I will use a 240ac DPST NO relay as a latching relay. One pole to hold the relay in until a thermostat opnes, the other to control the HW heater power. Press a button, the relay latches and stays latched until the HW heater thermostat shuts off the controlling element.

I would like to change the HWH from sequential to simultaneous operation. What are the advantages/disadvantages to this change and are there any dangers in this change.

Thanks, Norm Bandership@earthlink.net

Reply:

Norm,

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.

Daniel

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

Reply:

Aaron,

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.


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Continue reading  at ELECTRIC WATER HEATER HIGH TEMP CUTOFF TEST or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see ELECTRIC WATER HEATER CONTROL FAQs - questions & answers posted originally on this page

Or see these

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