Hot water tank element reads 20.5 what is wrong

Safest method:
Shut off electricity to heater.
Shut the water valve.
Drain heater to below the level of the element, open hot water valve in house to vent heater to speed draining.
If the element is on top, you don't have to empty the heater.
Remove old element, install new element.
Leave hot water valve open somewhere in the house.
Turn water on.
Once air is removed at hot water valve, turn electric on.
Shut water valve.

Gary

I had this same EXACT problem. I replaced both elements, and STILL no hot water. Power to everything, but no hot water. So, I got online, and got educated.

THEN what I did was to replace the Thermostats, both the top (master) and the bottom. Cost was reasonable, I think all told it was 24.00 for both elements, and about 40.00 for both thermos. Got the thermos at the same plumbing supply store where I got the elements.

This fixed my problem, I now have great hot water.

The way the water heater works is that the top thermo is the master, and when the water needs to be heated, it turns on the bottom one first. This is because that when you turn on a tap, the hot water is taken from the TOP of the tank, and the new water coming into the tank comes in to the BOTTOM. This means that during normal operation, the water in the top of the tank will pretty much stay hot, and only the water in the bottom will need to be heated. Your bad Thermostats are not reading the temperature any more, so it isn't sending power, (or rather grounding) the circuit to the elements. Since the entire tank is cold, it is probably the top one that is bad, since it turns on the the lower element (or, I should say, the lower thermostat) FIRST. The elements always have power, the switch in the thermos just works by grounding, and thereby completing, the circuit.

Either one of your thermos could be bad, or both. I thought for myself that if one went bad, then it won't be long till the other goes bad too, so I just replaced them both. On mine, they just snapped out, and snapped back in, they just kind of sit against the tank, and there is only 4 or 5 wires to hook back up.

I am assuming that you are competent to do it, since you already know how to replace the elements, and obviously have a voltage tester to see if you have power everywhere you supposed to have it. One thing, too, make sure that both of the Temperature Stettings on the thermostats are exactly the same. You do not want one to read 125, and the other to read 150, or whatever. Set them both to the same temp.

This should fix ya, and it is a heck of a lot cheaper than a whole new water heater. The only reason to completely replace an electric hot water heater is if the tank has rusted through and is leaking, or if it has filled up with sediment. Or physically damaged in some irrepairable way. Other than that, this cheap repair should do it.

Good Luck To You.

Hi,
The unit probably has two heating elements and the bottom one is burnt out, therefore only the top portion of the tank is heating...

check and change the bottom heating element.

heatman101

1) If upper element is receiving 240V, then water heater should have some hot water.
If upper element is burned out, then tank will have no hot water, but element will still test for 240V
http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

2) Keep in mind that upper element heats top part of tank first.
Only when top part of tank reaches thermostatic temperature will power be sent to lower thermostat and element. This is called non-simultaneous operation.
http://waterheatertimer.org/How-it-works.html

3) Non-simultaneous operation is necessary for most water heater installations because both elements are not ON at same time. Either upper element is ON or lower element is ON or both are off.
Each element is typically 4500 watts, which is 18.75 amps.
If both elements were ON at same time, it would consume 37.5 amps, so circuit breaker would have to be 40 or 50 amp with 8 or 6 gauge wire.

4) Add a comment with your experience so others with same-similar problem can benefit.

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Your water heater has 2 elements so its 240Volts.

1) If breaker is delivering power on one leg of the 240Volt circuit, then water heater can appear to have electricity, but tank is receiving 120V. Both 120Volt legs are needed to complete the 240V circuit. Double check for 240Volts.

2) Review electric Load.
Water heater label shows wattage of tank.
If tank is 4500Watts for example, you installed 3500 or 4500 watt elements.
With 5500 Watt elements you need 30 amp breaker and orange-colored 10 gauge wire
With 4500 Watt elements you can get by on 20 amp breaker and 12 gauge wire up to 75 feet away.

3) Check ECO red reset button on upper thermostat. If reset is tripped, then ECO is reading high temperatures. Suspects at this point are defective upper thermostat, shorted wire or bad lower element.

4) Also note that insulation and cover must be re-installed over thermostat. Thermostat reads temperature through wall of tank. If outside air circulates around thermostat, that can cause a mis-read and cause tank to overheat and ECO trips.

If you don't want to test the heater, replace both thermostats for about $25. Return the upper thermostat for a refund. Then see of problem persists.

Here's what I would do.
1. Check breaker for 240
2. Check water heater for 240 across 1 and 3 screws on upper thermostat
3. Note wiring and breaker size.
4. Note label on side of tank.

5. Look at end of new element to see wattage printed on each element. Look for sings of high heat and burning. Tighten screws on elements.

6. Check ECO reset button. Look for high-heat and burning. Tighten screws on thermostat.

7. Test upper thermostat as follows:
http://waterheatertimer.org/images/Electric-diagram-water-800.jpg
Test left-side #1 screw to right-side middle #4 screw. Test should read 240V at all times. If not, then ECO is tripped, thermostat is bad, or electricity is OFF

8) Water heater is cold so upper element should be ON. Test upper thermostat.
Test right-side #3 screw to left-side bottom #2 screw and it should read 240V
Test right-side #3 screw to right-side bottom #4 screw and it should read 0 volts

8. If upper thermostat checks out. Test upper element for 240 across both screws. If upper element does not read 240 when water is cold, then element is bad or there is a shorted wire between element and upper thermostat.
How to test element:
http://waterheatertimer.org/How-to-test-water-heater-element.html

9. Do a full troubleshoot on electric water heater
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

The top element only comes on when the heater is about out of water. The water is directed to the bottom of the tank. Cold water stays on bottom, Bottom heater element heats water. If you use all that water then the top of the tank gets cold and the top element comes. When the top of the tank is warm, then the bottom element comes on. I would susupect the bottom element as it does most of the work. If you have an ohm meter, turn off electric, and remove wires from element. Check element for continuity. If you don't get reading, then that element is bad.

Lower element will always test 120V to ground since thermostats turn off one hot wire.

Listed below are suspects in order of ease.

1) Check that hot water is not running out of TP valve and down into a drain.
This will cause water heater to run all the time but not be able to keep up.

2) Test elements before replacing anything:
http://waterheatertimer.org/How-to-test-water-heater-element.html

3) Test electricity to water heater:
http://waterheatertimer.org/Test-electricity-to-water-heater.html

4) Replace both thermostats.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

5) Final thing would be full troubleshoot:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

look for a badly connected power line ont he bottom element, or any connection upstream of the power terminals. voltage readings usually drop to that range when you only have one side of the 220v circuit connected.

Sounds like bottom element may be bad but usually reads open circuit if bad. Also tan k would run about 8 gallons hot water then go cold. lots of warm water usually means bad dip tube.
Check if tank is hot at bottom element when not used for a while. If bottom element is still cold then bad element.
If bottom element is hot - (all water in tank is hot then you have a bad "dip tube" This is allowing incoming cold water to mix with outgoing hot water. The dip tube is usually A part of the cold water nipple or B located under the cold water inlet nipple.

There is a thin plastic fill pipe in every storage water heater. Its where the cold water is fed in from the top... it travels the entire height to the bottom, as hot water sits on top. There is likely a crack in that tube. It is replaceable, but it is a very big nuisance depending on the size of your tank.
If thats not it, its potentially a weak high limit. Which shuts the tank heat off and never lets the tank reach it optimal temperature.