I'm renovating an old multi-family home and intend to live in one of the units. I like to take long hot showers, so I plan to replace the w/h for my unit with an 80 gallon w/h. This house has gas hookups for the water heaters rather than electric. Fine by me! But in shopping around, I've discovered that the largest gas water heaters they make are 50 gallons. If I want an 80 gallon w/h, I have to get electric. Why don't they make gas water heaters bigger than 50 gallons?