The house I recently purchased had a tankless water heater at one end of the house, it literally took 4 minutes to get hot water to the kitchen sink. It was 130 ft from heater to sink!! I insulated the pipes and it didn't make much difference. I installed a recirculating system, insulated the return line. I used an X-10 system to manually start/stop the recirc pump. Turn the pump on about 1 min before you need the hot water and you are good to go with unlimited hot water. My neighbor put in a recirculating system as he had the same issue with taking forever to get hot water. But he didn't put in any way to control the pump, it runs 24/7, his propane bill is sky high.