No expansion tank?
Guessing its a hybrid unit? I have a hybrid one by GE. Goddamn its loud.
Don’t forget to turn up the water temperature. Mine also was set to 120 by default, but that’s too cold. You need 135-140 or so, otherwise you’ll find that you run out of hot water pretty quickly, especially if you have people taking showers back to back, or running the dishwasher/washer while someones showering, etc.
What’s an expansion tank? I set it up like the old one was set up. All I did was disconnect the old one and reconnect the new one to the same pipes coming out of the wall.
An expansion tank is necessary for water heaters, because the process of heating water causes it to expand. Without an expansion tank, pressure could build to unsafe levels
If it’s necessary then how did my last tank make it 20 years without one?
If you are on municipal water and there is no check valve between you and the water meter then the municipal water supply is acting as the expansion tank. It may not be to code in your area but that’s how many homes were built in the past.
The expansion tank isn’t just for the water heater. That increased pressure puts undue strain on the entire plumbing system in your home. It will cause toilet fill valves to fail, supply lines to rupture, and possibly even pinhole leaks. A lot of plumbing issues are solved by installing an expansion tank.