Noise in the water heater valve. How do I fix it?

there is a thermostat control at the heater element that is adjustable
The temperature range is from around 55c to around 90c and if the water is almost boiling then I would suspect that that thermostat is not operating correctly
have an accredited electrician or plumber with electrical qualifications check it out.

The horrible noise you hear when the water heater fires up is probably caused by mineral buildup in the bottom of the tank. Hot water rises and flows by convection to the top of the tank. When you take a shower or turn on the dishwasher, the hot water you use is replaced by cold water that migrates to the bottom of the tank to be heated.

As far as the fix, regular maintenance is the key. The best thing a homeowner can do is to flush the water heater on a monthly basis. This simple process involves hooking up a garden hose to the drain valve at the base of the heater, opening the valve and with the water inlet valve open to maintain the pressure in the tank, allowing the water to flow until the water runs clean. Try this first. It may help. If not, de-liming is the other option.

Just replace the flush valve with another one.
Flush the water line by opening valve before attaching new flush valve

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Air in line??
Add air vent
http://waterheatertimer.org/Repair-water-heater-valve.html#air

http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#noise

Gene

Water Heater Timers Save Money

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Bad relief valve or too much pressure in the tank. Does water heater system have a pressure blotter tank that allows for expansion(an expansion tank)

Like a buzzing noise? Check valve where water lines connect at back will make a buzzing noise, if you only hear it when running hot water and not when running cold. Remove and replace it after shutting water off, and draining tank down. Be sure to shut off any hydro to electric element prior to draining.You can buy a replacement check valve, or just put a short 1/2" pipe nipple in there instead and reconnect your line, and refill it. noise should be gone .

Open following link to identify specific leak and remedy:
http://waterheatertimer.org/Water-heater-is-leaking.html

If TP valve is leaking: replace TP valve:
http://waterheatertimer.org/How-to-replace-TP-valve.html

If tank is rusted and ready to rupture, then turn water heater off:
Over next days, turn water heater on for short periods to make hot water when needed, then replace water heater.
http://waterheatertimer.org/Emergency-steps-for-leaking-water-heater.html

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What is probably happening is that you have a build up of minerals on inner tank lining and when unit is heat it expands the tank and the deoosits at a different rate which is what is causing the popping noise.
I would turn power off to your heater and hook a garden hose on to drain valve.Route hose to safe area as the water being drained will be hot. Open drain valve and see if you can get it draining good.If it is then shut off water supply to heater and open hot side of faucet nearby to prevent vacumn from slowing down draining. I would drain as much as I could then close drain valve and faucet and refill tank. I would do this several times to try to get all sediment flushed out.Hopefully this will help with your noise and make your heater last longer and work more effceiently. Good luck and thank you.

You have a water leak under the house, but need to know if it's a gas heater or electric. check the Pop off valve on top of the tank it has a short handle and should go threw the floor pull up on the valve and let it sit back down, if it stops the high pressure pop off valve is leaking, you can buy it and replace it for 5 or 10 bucks, if that does not stop it look under the house. Also use a broom stick and put the round end at the wall and the other end near your ear and check the wall and floor for the noise the closer you get the louder the sound. Hope this helps. If you look under the house and see water you know you got a leak in the pipes or the tank itself.

it might be hard water in the heater. the hard water flakes and when your water heater turns on it creates some movement in those hard water flakes and makes a popping and hissing noise then when it comes to temperature it should stop. the temperature and pressure relief valve shouldn't make this noise. but if you stick your finger in the pipe and it is wet then you might have problems some where else. let me know if it is