Hi! My water heater is about 8 years old, so I'm looking into getting a new one. I've looked at tankless, and they seem to be more efficient and last longer. My question is, do I need to upgrade my electric panel to install one? What are the requirements electrically to install one.? My electric panel is very old, and I think the largest fuses are 20 amp. My current tank heater uses natural gas. Also, is the installation very expensive? Any and all responses will be greatly appreciated. Thanks.