All tanked water heaters should have an expansion device, to protect both the water heater and your plumbing system. If all you have is electrical service, then I recommend a Heat Pump style water heater. Most Gas tankless water heaters have a service life of around 20 years if properly maintained. NOTE: Not all plumbers are qualified to work on tankless systems. So far I have not found any electric tankless models that performs as well as natural gas. Even the ones that perform mediocre require a large breaker and service wiring. Your existing electrical panel may not be rated for the additional amp load it may require. The Bosch 2.5 gallon Water Heater performed very well while it lasted and I would buy it again. These are available on Amazon for around 160.00 and will work on 120 volts. However, the outlet should be wired with 12-2 wiring. I believe the service life of these is around 4 years. Considering the low cost of this unit, its not too bad. If you would like to stay informed about the many issues our homes face in the Deep South, Subscribe to the New Channel I just created called "Building Science". This can save you thousands of dollars. Best of all it can provide you the knowledge to mitigate potential issues. The link to this and other channels are in this thread below. There is also informative articles on the facebook page "Southern Home Talk". "Knowledge Is Savings". Thanks for watching .By Building Science. Facebook "Southern Home Talk"   / 585940982070742   Tribute The Tribute Band https://www.youtube.com/@tributethetr... Building Science    / @southalabamahomeinspection2434