Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Quiet and Efficient

I've had this in operation for over a year with no problems. I also like that it is the lead compliant version. I use both the timer and the thermostat to control usage. I have a fairly long circuit of approximately 125 feet round trip (with no head). It feeds another 75 feet of pipe. I run this unit on the lowest setting and it provides nearly instant hot water. I did insulate the entire circuit with the foam insulator from Lowes. I did have a couple circuit design / sizing questions which the manufacturer was quite helpful on before the purchase.