Too much water draining from Vulcan Electric H/W relief valve.

turn off unit turn off water supply open drain at bottom let water out close drain remove valve

check your water pressure and then make sure it is not to high or all the problems you have had were not the answer. it is a pressure /temperature valve not just . temp.

Add an extrol expansion tank to the piping. You can get one for about thirty dollars from the hardware store.

Sounds like a plumbing problem.

Since no tap gets hot water, chances are good the problem lies in the hot water pipes between the water heater to the first Tee.
Look for sediment lodged in water heater hot water pipe.
Or sediment lodged in elbow or Tee.

Other problems can be in play.
Faulty check valve or mixing valve if these are installed.
Faulty recirculation system if this is installed.
Also crossover at single-handled faucet where the cartridge is bad and lets the cold water flow into hot water pipe whenever another faucet is turned on. If you are getting cold water out the hot tap, and you know the hot water heater has hot water, then crossover is suspect > in addition to sediment blockage at hot water heater.

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If you mean the drain valve, then buy garden hose cap at home center.
Cap will have rubber washer that seals tank.
If drain valve is plastic, the cap may not thread on without sanding down end of plastic drain valve.
Otherwise replace drain valve, which is simple if drain valve is brass, but can be difficult if drain valve is plastic.
Turn off power to water heater: Electric: turn off circuit breaker. Gas: turn knob to pilot.
Turn off water, open bathtub spigot on Hot side, drain water heater, remove drain valve with wrench.
If plastic drain valve breaks while being removed, then 'gently' break out broken part using hammer and big screwdriver.
Buy new drain valve at box store in water heater department.
Put teflon tape on new drain valve threads.
http://waterheatertimer.org/Water-heater-is-leaking.html
http://waterheatertimer.org/Water-heater-will-not-drain.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

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Suspects are lower element -or- either upper or lower thermostat.
If water heater has some hot water, then upper element is good, and electricity and circuit breaker to water heater are good.
Dual element tank is 240Volts.

Good news is tank-type electric water heater is fully repairable by homeowner using generic parts from hardware or home center:
Links below explain water heater repairs with step-by-step photos
http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/How-to-replace-element-and-clean-sediment-out-of-electric-water-heater.html
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html
http://waterheatertimer.org/How-water-heater-thermostat-works.html

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Hot water pressure relief valves serve two functions. The first is to remove high-pressure water from the hot water tank. The second function is to act as a high temperature valve to remove water that exceeds a predetermined point for the valve. Both of these relief settings are preset at the valve factory. Many pressure relief valves will come with a metal tag that identifies these release points. If you're attempting to remove the hot water heater pressure relief valve, pay careful attention to ensure that you replace with the correct valve.

Your hot water heater has a pressure relief valve safety mechanism. When pressure inside the water tank exceeds certain limitations, the valve opens up to allow the pressure to be released. A faulty pressure relief valve will not release excess pressure, which could cause extensive damage to your home. You should test the hot water heater pressure relief valve once every six months to ensure proper operation. If the pressure relief valve fails the test, replace the valve with a new one immediately

Locate the pressure relief valve on your hot water heater. The pressure relief valve has a lever handle on top with a drain pipe attached to it. The pressure relief valve is most often on the side of the water tank toward the top. Newer models of hot water heaters have the pressure relief valve on top of the water tank.

Inspect the area around the pressure relief valve for signs of leaking water. If there is leaking water near the relief valve connection, replace the relief valve. If no leaking is evident, proceed with testing the pressure valve.

3

Examine the area below the pressure relief valve drain pipe. Most water heater closets either have a drain in the floor below the pipe or the pipe is inserted into another pipe to direct the water out of the home. If the end of your drain pipe is not in another pipe or there is no drain in the floor, place a bucket under the drain pipe to catch water when you test the pressure relief valve.

4

Pull the lever handle on the top of the pressure relief valve up with your fingers. A working lever will lift up without difficulty.You should begin to hear water going through the drain pipe. Slowly release the lever to shut off the pressure relief valve. The pressure relief valve is good. If you did not hear water running through the drain pipe, lower the lever on the pressure relief valve and replace the valve. If the lever is difficult to raise, do not force the lever. Replace the pressure relief valve.

Now with all that said if you have a closed loop water supply system and you have a pressure vessal/expantion tank it may have gone bad and is making the TP valve leak. you can call your water provider to see if you have closed loop system.

The long drain pipe is the expansion relief overflow, it is too hot. The thermostats are too high. Or the valve is shot. Do you notice the water being too hot to touch? You might want to drop the temp a couple notches. There are thermostats on both gas and electric units. Also, do you have hard water? I have seen hard water build up on the expansion valve and cause it to leak, you could open that up for a second and let out some water to see if it will unclog it. Careful! Hope this helps.

Assuming you are talking about the temperatur/pressure relief valve, it is stuck open.

1. Turn off gas or electric to water heater
2. Close water supply to water heater
3. open hot water faucet on nearest fixture to depressurize hot water system.
4. close tpr valve (you may have to push in on the center spine. It may be resistant to closing from sediment. If so, opening and closing several times may solve that issue.

Once you get the tpr valve closed, close the faucet and open the supply valve. If the tpr stays closed, go ahead and turn on the gas/electric and re-light pilot and turn on control etc.

If the TPR blows again, you will need to replace it. YOu can buy a new one at any plumbing supply store. Shut down the heater again, drain a bit of water out using the valve on the bottom of the tank. there is probably copper pipe connected to the TPR valve which you may have to cut or maybe can just unscrew. The TPR threads out of the tank, install the new valve (make sure to use pipe dope or teflon tape.

look can look to wear the water nis comeing from