Homeowners should generally call a plumber once every two years for a newer plumbing system. If you live in an older home or have had frequent repairs in the past, an annual plumbing maintenance program may be the best option. It's important to perform a maintenance inspection of your plumbing annually, just like you do with your heating and air conditioning system. Any system in your home that receives daily use should have a professional checkup once a year.
Nobody wants to be without hot water for an extended period of time. Your grandmother may have heated the bath water on the stove, but that's not necessary these days. A plumber is the best person to call for this issue, as they are experienced and can tell you if you need a new heater or if the existing one can be repaired. If the heater needs to be replaced, your plumber can take the new one to the basement, connect it, make sure it works properly, and dispose of the old one.