Hot water tank problems

Hello, I am having a problem with my hot water tank. Heres the story.
So a couple of years ago, our original hot water tank started leaking and cause a lot of trouble in out house so we replaced it with a new hot water tank. This hot water tank worked for maybe 1-2 years then started leaking from the pressure release valve. We called a plumber and he attached a big roundish thing to the top to collect the pressure or excess water something like that. This helped for another year or so but then the water came back again. So for about a year, we've been connecting a hose to the valve and put that to a drain so water won't go everywhere. A couple of days ago, i found out changing the pressure release valve might make the leaking stop. So I went out, bought a new one and changed it. A hour or so later, the water started leaking again. What are the possible problems of this and ways I can fix it. Help would be very much appreciated.

Thanks.

ps. the hot water tank is a electric one with valve on top. thanks

You need to get a pressure gauge and check the static pressure on your home, you can try the drain at the bottom of the heater if it is in good condition.
If pressure is above 80 psi you need to replace your pressure regulator or install one of you don't have one.

Get a pressure gauge that attaches to a garden hose faucet. Use that to check the water pressure. Then shut the water supply off to the water heater, drain off all the pressure, and check the air pressure in the expansion tank (big roundish thing the plumber installed). The two numbers should be close. I am guessing that you need to add some air to the expansion tank.

Thanks! will give it a try

Let's not forget that most plumbers do NOT charge the thermal expansion tank to match the house pressure. This may give the impression that the thermal expansion is remedied, but instead over extends the bladder, reduces acceptance volume on the TET and shortens the life expectancy of the thermal expansion tank.

Just ignore the spammer, who is trying to get some free publicity.

with eggs??

Make sure that you get the right part. You need to buy a wrench and Teflon tape and spend two hours running to/from the store, it's worth it.