water heater - TPR valve opening

When the old, galvanized supply piping to the house was replaced with copper, the TPR valve on the electric water heater started intermittently opening. The flow at fixtures in the house has increased because the old piping had a lot of restrictions. The static pressure on the cold supply is 60 PSI. There is an expansion tank on the outlet of the water heater. Could the expansion tank or TPR valve have been damaged by scale from the old piping ? Is an expansion tank needed on the inlet to the water heater ? Is a larger expansion tank needed ? Any advice would be appreciated.
Thank you.

has the expansion tank failed? Turn off the water...open a faucet to drain the pressure, then use a tire pressure gauge to see two things - one to make sure no water comes out - a sure sign the bladder is shot, and two to see if there is any pressure in the tank. If there is no water that comes out of the valve, but the pressure is low or non-existent, try pumping it up (BTW, what should the static pressure be in a tank like this?). Well, before you do that, try knocking on the tank to see if it sounds hollow in at least part of it. If the whole thing sounds like it is full of water, it probably needs to be replaced.

It is also possible that in the process of replacing all of the piping, you got a bunch of rust/scale - the inlet to the tank may be clogged. My unprofessional opinion.

Thanks for the advice. I will see what I can find with the expansion tank.

no pressure in tank

I found that the tank has no pressure. So it seems to have failed when the other work was done. The label on the tank gives 40 PSI as the working pressure. I assume this is what the air side of the diaphragm should be.

geof said:

I found that the tank has no pressure. So it seems to have failed when the other work was done. The label on the tank gives 40 PSI as the working pressure. I assume this is what the air side of the diaphragm should be.

Click to expand...

You have to check the pressure before you release the pressure in the system. If water comes out, then the tank is defective. If the pressure is zero, then the air valve may have let the air escape. Once you know what is wrong, then you can shut the system off and release the pressure. If it just needs air, leave the faucet open while you pressurize the tank. If it is defective, unscrew it and install a new tank.

Thanks for clarifying. I think the tank is defective.