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Guide to Electric Hot Water Heaters - Inspection, Diagnosis, & Repair
PlumbingAPedia ©
- Electric Water heaters: how to inspect, test, adjust, repair
- How to choose among types of hot water heaters
- Guide to inspection of electric water heaters
- No Hot water? how to get more hot water flow, quantity, performance from your water heater
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Our site offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
inspect-ny.com/appointment.htm.
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.
This page 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. Reproduction of this web page electronically at other websites is prohibited.
© Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left.
Inspection, Diagnostic, & Repair Guide to Electric Hot Water Heaters
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How do we identify an electric water heater?
The sketch at left shows the basic components of an electric water heater and is provided courtesy of Carson Dunlop. It's easy to identify an electric water heater:
if you can find your water heater tank at all, take a look at what pipes and wires are connected to it. If you do not see any connection to a chimney, and if you do not see any oil or gas burner, your hot water tank is going to be one of these:
- An electric water heater: you'll find an electric wire entering the heater, usually at the top, and connected to a fuse or circuit breaker in your main electrical panel. Usually the circuit supplying power to the electric water heater will be 40A or larger. There will usually be just two water pipes connected to this device: cold-water in and hot-water out.
- An indirect-fired water heater: you'll find a circulator pump and four pipes connected to this water tank. See Indirect-fired Water Heaters for photos and details.
- A range boiler: you'll find four pipes connected to this water tank, no electrical wires. See Range Boiler Water Heaters for details and photographs of range boilers.
- A solar water heater tank: you'll see lots of pipes and wires connected to this tank, a circulator, controls, and more stuff. See Solar Water Heaters for photos and details about solar hot water heating.
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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.
Here are a few things to check on your electric water heater:
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(WARNING: This is an INCOMPLE LIST and important water heater inspection topics may be omitted as we're working on this section. If you have comments, questions, suggestions, Contact Us.)
Check the pressure and temperature relief valve on your water heater: look for evidence of corrosion, leaks, improper installation, etc. A missing, modified, blocked, or leaky pressure relief valve is extremely dangerous and can lead to a catastrophic BLEVE boiling liquid vapor explosion that can cause severe damage or even fatalities at a building. See Relief Valves - TP Valves
Look for evidence of leaks in the hot water tank, or mechanical damage, or improper installation. For example most water heaters are intended to be installed in a vertical position. Installing a hot water tank horizontally or in a hole in a crawl space is likely to cause early failure of the heater, violate the manufacturer's guidelines, and may be dangerous.
In our photo at left an oil-fired water heater and an indirect-fired water heater are installed in tandem. That puddle on the floor needs investigation.
Check the settings of the water heater temperature: See Temperature of Hot Water is Too Low. On an electric water heater, temperature settings are usually made on a control hidden behind the upper and/or lower removable access panel covers that give access to the upper and lower heating elements.
Look for insulation that has been improperly added to the water tank - it may be unsafe. See Insulate Hot Water Tank?
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Check the piping and control valves connected to the water heater for leaks, support, and for proper location of shutoff valves. An improperly installed shutoff valve on a water heater can be very dangerous, risking an explosion. Usually the "hot water tank shutoff valve" is installed only on the cold water pipe coming into the water tank. There should be no shutoff valve installed on the hot water line leaving the water tank.
Check for leaks at the water heater drain valve. Most water heater manufacturers recommend that their water tank be drained periodically. This process will help remove sludge and debris or mineral deposits that may have accumulated at the bottom of the water heater tank. Removing this debris can extend the life of the hot water tank, especially where electric and gas fired water heaters are involved. But since few people remember to open and drain the tank it may be that the drain valve does not open easily, or worse, it won't close.
- Tips On Draining the Water Heater Tank: Don't try opening the hot water tank drain valve without first noting these warnings and tips:
- The water heater heat source should be turned off and the water tank cooled down (or run hot water out through building fixtures) before attempting to drain the tank - there can be a serious scalding hazard otherwise
- You can connect a garden hose to drain the water heater tank to a suitable destination
- If it's a Sunday - you may have trouble obtaining spare parts or emergency plumbing service if a problem occurs
- Be sure to have a spare garden hose cap to install over the end of the drain valve in case it drips and won't shut off completely
- If you have trouble turning the water heater tank drain valve to open it - don't force it - if break off the valve stem you may have a leak that you cannot shut off except by turning off cold water supply to the water heater
- After opening the heater drain valve, if you forgot to turn off the cold water supply coming into the water heater, you may find that water just shoots out of the drain forever - you'll need to turn off the cold water supply to the water heater.
- You will probably need to open a nearby hot water tap to let air into the plumbing system and through it into the water heater tank so that water can drain out at the tank's bottom. We don't recommend opening the pressure/temperature relief valve for this purpose as you may find that the TP valve won't shut successfully afterwards.
If plastic water piping is installed, such as polybutylene water supply piping, it should be at least 18" from the water heater.
Vacuum relief valves are required at water heaters in some communities, to protect against collapse of the water storage tank and to prevent backup of hot water into the cold water piping should cold water pressure drop. Here is Carson Dunlop's sketch of a vacuum relief valve.
Electric Water Heater Controls & Operation
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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.
- A pressure/temperature relief valve - See Relief Valves - TP Valves
- Cold water in and hot water out supply piping
- A cold water inlet shutoff valve
- A water tank drain valve
- A thermostat to set water temperature, located at one (or both) of the electric heating elements - Refer to our diagnosis of a failed electric water heater element at Temperature of Hot Water is Too Low.
- An electrical switch to turn power off to the water heater;
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Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank
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At Temperature of Hot Water is Too Low we explained that a leaky dip tube in a water tank can result in hot water temperatures that are too low.
But the dip tube on many water heaters also 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 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 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.
It's a relatively small plumbing job to disconnect water pipes from the water heater and then pull and check, and replace the dip tube/sacrificial anode if necessary. |
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.
The articles listed below describe the inspection, operation, diagnosis, repair, and improvement of each type of water heater, and we include detailed advice about how to improve hot water supply in buildings as well as inspection and correction of leaks, high hot water costs, odors, noises, and safety problems.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Technical Reviewers & References
Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to
the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.
- Daniel Friedman - principal author/editor of the InspectAPedia TM Website
- Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
- Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
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