I had a licensed plumber (checked with the state to make sure) come out and check the expansion tank to make sure it was still working. He said it was fine. He also said that since there was usually always someone home (and using water) that we really didn't need it. (We do have a pressure regulating valve--one with bypass). I asked about checking the TP valve on the water heater and he said he tells people to leave it alone even though the WH manual says to check it once a year. Now I'm really confused. Our old plumber (found out not licensed) always released the TP valve when he worked on the water heater and said we needed the exp tank. How does the average person know who to listen to and what is right when there are 2 different opinions?