How do you size an expansion tank. I will be replacing all piping & gas heater. I see 2 gallons & 5 gallons at the store...
I will be placing a 40 or 50 gal. gas water heater.
Two gal. is large enough.
Two gallon should be fine. just make sure you pressure the tank to your water pressure. Usually they come precharged at about
40lbs. If you have a water pressue gauge just set exp tank the same. pretty easy task.