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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 DIAGNOSIS & REPAIR
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 Plexvent / Ultravent RECALL
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 CONSERVATION MEASURES
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 diagnosis & repair procedures: here we explain how to test and repair an electric hot water heater that is not heating at all or is not producing enough hot water. We start with simple basic checks and then move to testing and replacing bad controls or bad water heater elements.
This series of articles describes how to inspect, operate, diagnose, and repair electric hot water heaters. 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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The cause of no hot water at all coming from an electric water heater might be
In this article we discuss these four possibilities in the order we've listed above.
If there is some hot water but it is limited in quantity or temperature, just one of the heating elements may have failed. Scale coating a water heater element can also reduce the quantity of hot water (or cause heating element failure) - a topic we review in more detail at at WATER HEATER NOISES.
If your electric water heater has stopped working entirely, or if it produces less hot water quantity than normal, or the electric water heater produces warm but not hot water, the diagnosis of the water heater problem is pretty easy, and sometimes the repair is easy and inexpensive as well. Here we outline steps to inspect, test, and repair an electric water heater.
Check the water heater for leaks. If the water heater tank itself is leaking, you almost certainly need a new heater. We discuss water heater leaks at Electric Water Heater Inspection Checklist - while you're at it, go through that checklist: while getting your electric water heater working properly you may find and need to correct other defects including some that are important for safety.
Check the circuit breaker or fuse for the electric water heater. The heater is usually fused in the main electrical panel but some electric water heaters may be fed from a separate fuse or circuit breaker box. If the fuse is blown or breaker is tripped, replace the fuse or re-set the circuit breaker. If the fuse blows again or the circuit breaker trips again, do not re-fuse or re-set the breaker as the system is unsafe and you need a professional electrician.
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. See TIMERS for ELECTRIC WATER HEATERS.
Check the water heater thermostat condition and its internal thermostat control reset switch. Below we show how to find the thermostat control and reset switch for an electric water heater. See Electric Water Heater Reset & Temp Set.
If all of these items check out OK the water heater may have one or both of its heating elements burned out. We discuss finding, testing, and replacing an electric water heater heating element below.
Electric water heaters usually have two thermostats, and to heating elements: an upper thermostat located behind a cover high on the heater tank, and a lower thermostat located behind a panel low on the water heater tank (photo at left).
The two access panels permit inspection, adjustment of the thermostat(s), access to an internal reset switch (that you may not have known about), and access to electrical wiring as well as access to the actual heater elements should one or both of them need to be tested and/or replaced.
Sequence of Operation of Electric Water Heater Elements
Most electric water heaters are what we call "flip flop" or "non-simultaneous" electric water heater systems, meaning that just one of the two heating elements is working at a time.
When the hot water heater's tank is full of all cold water, the upper thermostat flips on, heats up the water in the upper portion of the heater. That's also where hot water exits to the building - from the top of the tank at the hot connection.
The upper heating element heats about 1/3 of the water heater's volume, while the lower element heats the bottom 2/3.
Once the temperature set on the upper heater's thermostat has been reached, the thermostat control will then flip power down to the lower thermostat that controls the lower heating element. The lower thermostat switch will turns on the lower heating element and that in turn heats water in the bottom of the water heater until that water reaches the temperature setting on the lower thermostat.
Now the whole water heater is "hot". Of course life is more complicated. When the water heater is in use cold water is entering at the tank bottom (out of the end of the dip tube) but also somewhat mixing up water in the tank. If the upper tank is still hot, cold water entering in the tank bottom will contact the lower element and thermostat and those will turn back on.
A.O. Smith (water heaters) has an excellent service handbook that explains these operating modes and instead of flip-flop they call it "non-simultaneous operation" of the electric water heater elements.
It is possible to convert some flipflop electric water heaters to operate the two elements simultaneously but as AOS points out you can't do that if the total amperage draw exceeds the circuit and equipment rating (say 40A).
Accessing the Electrical Wiring on the Water Heater
Behind each electric water heater panel you will see electrical wiring, a thermostat with a pointer and temperature setting numbers.
Watch out: Turn off electrical power to the water heater before opening the water heater access panels.
Otherwise you could be killed by electrical shock.
Smart repair people and owners use a neon tester or multimeter to absolutely confirm that electrical power has been turned off before ever touching electrical components.
We removed the upper panel metal cover (two screws), lifted off the styrofoam insulating cover, and revealed the water heater control in our photo at left.
If you break or lose the plastic cover that protects the water heater thermostat and heating element electrical connections, a replacement cover is provided with most water heater element replacement kits.
Also located behind each panel is the actual upper or lower heating element. Our photo (left) is the same location as we showed above, but we removed a plastic safety cover to show the electrical connections and other controls available here.
If setting the water temperature to a lower setting does not work there is a problem with the control and it probably needs replacement.
Just below we show closeups of the electric water heater internal reset switch (below left), and the water heater thermostat dial that sets the temperature control for (in this case) the upper heating element (since we are looking behind the upper panel on the electric water heater). This water heater is set to its maximum output temperature, 150 degF. If water leaves a faucet at 150 degF. scalding can occur in about 1 1/2 seconds.
If the electric water heater output water is too hot you can adjust the thermostat to a lower setting. Typical settings are 140 to 160 degF. Beware that any temperature above 120 degF. is scalding and a mixing valve may be needed for safety.
Our two photos above are of the lower heating element on this electric water heater. You can see from the burned and melted plastic that there was a problem with the lower heating element on this unit. But if you see this condition on an electric water heater whose history is unknown, do not assume that this is a current problem. On this water heater we replaced a burned-out bottom heating element several years ago, leaving the burned plastic cover and insulation cover on the unit.
Above are photographs of a replacement electric water heater upper thermostat (including its reset button) and the smaller lower water heater thermostat. Wiring details provided with these water heater controls are at Electric Water Heater Element Replacement.
At links below we continue with more diagnostic testing and repair procedures for electric water heaters, looking at the high limit cutoff switch, the high temperature reset switch, and testing and replacing bad electric water heater electrodes.
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
Question: Compatibility of Water Heater Thermostats & Controls
I replaced the upper thermostat with the equivalent thermostat of a different brand (whirlpool - new, apcom - old). The original plastic shock protector doesn't quite fit right as the layout is slightly different (the reset button is in the same place, but the temp control is now covered up, and the element terminals are covered but just barely). I cannot find anywhere to get a new protector for the whirlpool thermostat. Do you know where i might find one?
George, If Whirlpool cannot provide you with a new plastic cover to protect the electric water heater control contacts from shorting, your choices are reduced, in my OPINION, to either
Question: We suspect a burned out electric water heater element - how do we know if it is the upper or the lower heating element?
Usually if the upper element has burned out you'll find that the quantity of hot water has not been reduced as much as you'll observe that the water provided by the heater is tepid.
And if the lower electric water heater element has burned out you'll find that the water supply may be plenty hot, but less in quantity.
You can understand why these simple diagnostic observations usually work on residential electric water heaters by looking at Carson Dunlop Associates' sketch at left. For commercial electric water heaters, because both elements usually operate simultaneously, this distinction won't apply.
Of course the heating elements can be tested to see which is burned out (open, or infinite resistance) or shorted (zero resistance), as we describe in detail at Electric Water Heater Element Tests
Reader clarification: here is the usual sequence of operation of residential electric water heater elements
Editor's note: typically, cold water entering the electric water heater near the heater bottom (thanks to the dip tube) turns on the lower heating element when you begin drawing hot water out of the water heater tank (at the tank's top). When the water near the top of the tank cools (by rising cold water coming in at the tank bottom) the upper heating element comes on and the lower element shuts off. This gives priority to heating the outgoing hot water from the top of the water tank.
When the upper heating element has heated the water to its cutoff temperature (which won't happen if you continue drawing hot water rapidly out of the tank), it allows the lower element to turn back on. Details are in our sketch above.- Ed.
Question: the reset button keeps popping out on our electric water heater control
When I reset the upper t-stat with red button fire jumps from wires on t-stat= water heater is a state select water heater.- Richard Cox 2/6/12
Richard, it sounds as if there is a short in the wiring, the element, or the control.
Also, there was evidence that a short had occurred in lower element region as there were burn marks on or near cover or where there was an electrical malfunction, both elements have been replaced, and still no hot water, both elements appeared to be normal when removed.
Question: small white particles coming out of our hot water heater clog our faucets
I have small white particles that clog my faucet water savers I was told that plastic material was used in some water heaters and this deteriorates over time, causing this problem. Is this true? I have an A.O. Smith 55 gallon water heater made in 1995. - Bill 2/5/12
Reply: Replace the plastic dip tube that has disintegrated and flush the water tank to remove the debris
Reader Red Wood and others pointed out that plastic water heater dip tubes supplied by the Perfection Tube Company and installed in nearly all water heaters made between 1992 and 1997 proved to be defective with the plastic used disintegrating and producing the debris you describe.
At DEBRIS in WATER SUPPLY, Water Heater we describe and illustrate with photos the diagnosis and correction of these white plastic debris particles left in the water heater when a plastic dip tube disintegrates.
At WATER HEATER ANODES, DIP TUBES we describe inspection and replacement of water heater dip tubes. To help other readers we've copied your question and posted a longer reply at the Debris article cited just above - Editor.
Reader Comment from Red Wood 
Question: should the upper and lower temperature thermostats be set the same on a water heater? what if I replace a heater element but still don't have much hot water?
When adjusting the temperature do you keep the upper and lower thermostat the same ? - John 4/15/12
I have replaced both T-states and both Elements and I still only have a small amount of hot water? - Patrick 1/22/2013
that makes sense to me. I will research further. Also take a look at the electric water upper and lower heating element sequencing operation described at Electric Water Heater Element Tests
I suspect that either one of your elements is not heating ( a bad element or bad wiring) or a thermostat or controller is not turning it on. If the total hot water quantity is small, check first for a bad LOWER heating element.
Question: where do I find the reset button on the water heater? other electric water heater reset button Q&As
hi how do you locate the reset button when theres insulation on cylinder thanks - Trevor 09/25/2011
The red reset button works for my electric hot water heater but after a few days I have to reset it again. I drained the water heater until it was clear, and I know both heating elements are working. No hot water at all, not even luke warm. - Nathan 6/28/12
Reset button will not reset on electric water heater replaced upper thermostat still will not reset - Russell 1/14/2013
2nd time in a month, I've had to push reset button. to get hot water working again. s this the start of something going out? Or just normal. Thank you for you help. - Tim 12/3/2012
My reset button light is very dimm and the water is not heater. I have replaced the upper element and the control board and the still no hot water and the reset light is dimm.- Lee 1/21/2013
Trevor, quite so, if everything on a water heater is covered up by add-on exterior insulation you can't see a thing - and the system may be unsafe too, especially if the pressure/temperature relief valve has been covered over.
these thermostatic controls can fail themselves. If the elements are not shorted and there are no other electrical problems you can find, I'd replace the thermostat unit.
Before replacing a water heater element I'd check to confirm that it is defective. In the case you describe the problem could be a bad second heating element OR the thermostat unit itself could be defective.
See Electric Water Heater Reset Switch in the article above.
Test and replace one or both bad heating elements - if they're bad. If the two heating elements test out as OK I would replace the thermostat unit.
Question: solar water heater with electric backup, - can I disconnect the red reset switch?
I have an 80 solar water tank with electric backup, mixing valve, upper heating element only, PT valve and solar panels upper manifold air release valve. Occasionally, the water reaches boiling and the PT and air valves do their job but the red element reset switch pops off too. This means going up into the attic. Can I in any way disconnect the red reset switch? I presume this switch is not electrical but a bimetal strip mechanism, right? - Jeff 11/30/11
I'd consult with a solar expert on how to control the system temperature,
Watch out: I would never disconnect a safety device. A combination of multiple errors could still lead to an overheated exploding water pressure tank - a catastrophe (search InspectApedia for BLEVE to read what can happen). I just wouldn't take a chance.
Question: pumping noise from my water heater
my electric water heater has a pumping noise and the top valve is going in and out slightly i have no hot water the panel is on top of the tank temp reset etc and lights are green what is wrong... - Carole 11/20/12
Carole, I don't understand the question nor what's going on with your water heater, but I'd sure call a plumber and ask for a diagnostic inspection and if needed, repair.
For a description of water heater noises that we understand, see NOISE, WATER HEATER
Question: dead hot water heater after an electric power surge
We had a power surge last night .My hot water heater wont come on. I checked the breaker and reset it. I tried the reset button .Still wont come on .Any suggestions please - Penny Thompson 7/26/12
A power surge can damage an electrical panel, circuit breaker, fuse, or an electronic control, possibly in equipment in the home. I'd start by making sure that the water heater is receiving electrical power, then try pressing the reset switch on the control. If you have power and the switch won't reset, it's time to call a service technician.
Question: wiring water heater thermostats
I have an old 6 wire upper water heater 'stat. The newer upper 'stats are 5 wire. (I' talking wire lugs) How do I re-wire the newer 5 wire models? - Jim 9/7/12
Jim, take a look at wiring details at ELECTRIC WATER HEATER ELEMENT REPLACEMENT - the replacement units I've seen include very clear wiring schematics right on the package.
Question: water heater made an exploding sound
I have a new (about 1yr old) whirlpool electric water heater (80G). I have a renter who says the water heater made an exploding sound. water is from a well. pressure is about 40PSI. the pressure relief valve shows no water leakage, but the pan has about 1/2 in of water in it. whirlpool said to check the temperature setting and upper and lower plugs for water leakage.. but that's about it. maybe temp control valves are defective. anyone ever heard of this? I will drain the pan and un-bypass the unit and leave it operational. i will set the thermostat to a lower setting to see if it is still coming out hot. anyone ever had this problem. just about everyone i talk to is stumped. - bill Huttle 9/11/2012
Sometimes, water heating inside a water heater, particularly one with scale deposits, can make crackling, rumbling sounds that might sound to some like an "explosion"
Question: lower water heater element failed - I can't get the old one out
Help. My lower water heater element went out and I went to replace it. I followed all the instructions, and proceeded to remove it. The element is not coming out because it seems misshapen at the end and is too large to fit through the hole. I have no idea how it got inserted in the first place, the irregular shape must have happened inside the heater. Its from 2002 and a Bradford white model _ Tammy Friedman 10/21/2012
I've seen this problem, and it's annoying, agree. In fact, working carefully we've been able to get a deformed electric heating element out through its mounting hole by bending, even cutting one end of the element itself, but the trick is to work carefully to avoid dropping trash or broken debris into the bottom of the heater tank; if you do so it won't be a catastrophe, but the risk is debris clogging of water piping, faucet strainers, etc.
Question: overheating on electric water heater
I changed the element on my fathers boiler it only has a single top element
War, I'm not sure where the problem lies on your heater, but I'd start by being sure that the replacement element has the same wattage element as the original one. If you installed a mis-matched electric water heater element it may indeed be overheating.
Question: water heater output water is just too hot
2 days ago we began getting extremely hot water from our water heater. Our thermostat is still set very low so we are surprised and confused. There is also a slight metallic smell in the water and slight odd taste. Can you help us determine what's going on. - Becky NOrthrop 10/2/12
Most likely the thermostatic control on your water heater has failed and needs replacement. See ELECTRIC WATER HEATER HIGH TEMP CUTOFF TEST for details.
Watch out: failure to replace a bad thermostat and overheating hot water is dangerous and risks scalding burns or worse, a BLEVE - explosion.
Question: 10-16 ohm readings on water heater elements vs 30 ohms
I tested both Water elements expecting readings of between 10 and 16 Ohms, both came back with readings slightly over 30 Ohms, does this indicate some other problem, I checked the multimeter and it is working correctly? - Jon King 12/12/2012
Jon, check the table of ohm readings above - you'll see your elements could be in normal range
I am connected to a well and I have a water softener. I been noticing that at the exit of the water softener when I did connect the pipe the water coming out of this cold water supply to the house is hot. I don't have any other outlet with that problem, and the water softener is the closes to the hot water tank. Could my hot water tank have a problem and need replacing, it is over 19years old. - Normand 12/24/12
More likely the dip tube on your water heater has disintegrated, allowing hot water from the top of the heater to pass back up into the cold water supply piping. If that's the case you may get some more life out of that old heater.
Water leaking from bottom element trips the breaker it makes a popping noise inside it tank - Ron 1/1/2013
water is streaming out of my hot water heater and the water is raging hot for about 4 day. i don't know hat to do, and what is the problem - Misty 1/5/2013
Reply: The correct leaky water heater repair depends: first ee what part of, on, or near the water heater is actually leaking
If a water heater is leaking you should take these steps:
If you hear a dripping hissing sound at a gas or oil fired water heater typically you're going to find that the bottom of the heater tank is leaking and dripping into the combustion chamber. The heater is shot.
If you hear a hissing sound at an electric water heater that may be "normal" as the electric heating elements are heating up.
Check for water heater leaks around the T/P relief valve: If you see water on the floor around the water heater and by inspection you cannot find any leaks in pipes or connections to the water heater itself, I suspect the problem is the tank, but another possibility to check first is for leaks around a tank side or top mounted water heater pressure/temperature relief falve. If the valve was not properly secured and sealed, leaks around the valve mounting threads can leak down through the insulated jacket of the water heater, eventually appearing on the water heater burner or on the floor around the unit. In this case the heater might be repairable. But be sure to see our warnings at FLOODED WATER HEATER REPAIR
Question: what do I do if after replacing the water heater heating elements I still get no hot water?
I put in both heating elements and the upper thermostat and still cant get hot water what's should i do next - Earl Baker 2/19/2013
i have replaced both elements @ thermostats @ the reset switch but the reset switch
@Pat---I got same problem. Changed out everything and still trips red reset. Did you figure it out? - Bill 3/16/2013
Pat and Bill,
Question: water heater circuit breaker keeps tripping: diagnosis & repair - Pushmatic Breaker
The circuit breaker keeps tripping on my electric hot water heater. The heating elements are new (we initially thought they were the problem), theres negligible corrosion and the anode rod is ok. There's no evidence of electrical shorts. Once the heater cools a bit the breaker can be re-set, but trips again within 15 minutes. I have both thermostats set to only 102 degrees but the problem persists. I suspect faulty thermostat(s) causing the element(s) to overheat. Can you shed some light on this? Thanks! - Jeremy 3/16/2013
The circuit breaker takes longer to trip the lower I set the water temperature, which makes sense because higher water temperature settings require more current. But no matter what it does eventually trip. Closer inspection of the 240V breaker did reveal burnt contacts; I will replace the breaker and re-evaluate the water heater's performance. Much obliged, Dan!
This is an old 40A 2-pole Pushmatic breaker switch; the contact is burnt on the side where power enters the breaker, not the wiring connection that leads to the water heater. I will need to investigate the wiring to the breaker box if this occurs again with a new breaker.
What we don't know in this case is whether the burnt-up Pushmatic breaker occurred just because of internal flaws in the circuit breaker, or if in fact the breaker was being subjected to protracted overcurrent conditions (say because of problems at the electric water heater).
Also watch out for aluminum electrical wiring - it is common (and legal) for an electric water heater to be powered by a multi-strand aluminum wire, but if the connections were not made with exquisite care (and maybe even regardless) overheating and burn-ups can also occur at the aluminum wiring connections - risking a fire and loss. Statistically, because an aluminum-wired water heater circuit has many fewer connections than say a string of aluminum-wired electrical receptacles, the heater circuit risk is less. But subjected to overcurrent and heating from problems at an electric water heater itself could increase the risk of a circuit or breaker failure showing up as well. See ALUMINUM WIRING HAZARDS & REPAIRS.
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