[jrref]

Quote " The WH is original as far as I know and the house was built in 2007"

What???

We have talked about this topic over an over but as many have said, Hot water heaters, generally last from 6 -12 years depending on the brand and model. The fact that the pressure release valve is opening means there is excess pressure in the tank and that's very dangerous. It's probably from the expansion tank being bad. They only last about 5 years and need to be replaced.

At this point instead of an approximate $1,200 tank replacement, you now have a way more expensive job on your hands. This is why you should always look at the label on your tank to find out how long it's warrentied for and replace it, whether it needs it or not, within a year after the warrenty, at your convenience. If you do this when the tank is replaced the plumber will check everything and replace the expansion tank, etc, and the chances of you having a problem will be extreemly low. Some might say wait until the water heater leaks before replacing it or repair a very old water heater, or say the pan will catch the water and there is a drain to the outside of the house so don't worry BUT after the warrenty period of the tank ends you are gambling on when the water heater will fail. Sure you will have the homeowner say "my water heater lasted 25 years no problem" but you will also see many tanks will have a serious leak sometimes unnoticed causing mold and or the tank will let go and flood your house. Since you will never know when the tank will fail it's always best to just change it the following year or two after the warrenty period at your convenience. Rheem has a new water heater tank called Gladiator that has a built in water sensor and shutoff valve right on the tank to catch leaks. It's only a little more expensive than the "regular" grade Rheem tank and is more efficient.

You can check your expansion tank easily by tapping on the tank. You can flip your finger on the lower side and then the uper side of the tank or tap with a screw driver handle. The bottom should give you a thud sounding tap while the upper part should sound hollow. If both the bottom and the top sound the same like a thud sound then the bladder inside the tank has failed, it's not regulating the pressure in you hot water system anymore since the water in the system expands and contracts with temperature, and you need to replace it. You can also check the pressure in the expansion tank via the pressure valve on top of the tank. It should read about 40-65 lbs depending on the water pressure from the street. On some of these expansion tanks they were installed in such a way where it's hard to take a pressure reading. These tanks usually only last about 5 years.

That said, if your expansion tank is bad it's easily changed by your local plumber or you can do it yourself BUT make sure who ever changes it, that they pressurize the tank BEFORE installation to the approximate water pressure from the street or it will fail prematurely. I discovered that some plumbers skip this step since the tank comes prepressurized at 40 lbs. The instructions that come with the tank have the pressurizing step in big bold type so you need to do this no matter what the plumber says. Once this is done, when you drain the water heater yearly, ( and you will say "Who does this?" lol ), while the heater is drained you can check the pressure on the expansion tank and with a bicycle pump, pump it up to the correct pressure then re-fill the heater.

If you follow this basic maintenance as i said, the probability of having a problem with your hot water tank will be extreemly low.