I have a 15-18 year old electric hot water heater that needs replacing. The best place locally for me to buy one is at Lowe's. The old hot water heater is 47-gallon. My Lowe's only has in stock a 37 or 38 gallon electric hot water heater. My hot water heater is located under the house in crawl space so it has to be a low-boy, which the one at Lowe's is. When I bought the old one, there were four people in the house, but my children are grown and there is now only me and my wife. The house has approx. 1800 sq. ft heated space, with two bathroom. My questions is, will the 37-38 gallon heater be adequate now for our needs, or do I need to look elsewhere or have Lowe's order me a 47-gallon heater???