A homeowner in a sunny climate has the opportunity to install a solar hot water heater in his home for a cost of $4,000. After installation, the solar water heater will produce a small amount of hot water every day, forever, and will require no maintenance. This reduces his heating bill, which is paid annually. Assume an interest rate of 11% per year, with savings expected to be constant every year. How much must the homeowner save on water heating costs every year for this to be a sound investment? s (Round to the nearest dollar.)