I replaced a 25 year old controller for my solar hot water heater here in Florida. Direct replacement and worked with out any changes to the system other than replacing the electric valve. I hope it will last another 25 years. \r\nI did add a light to show when ever its on which is nice to know when it is working even on a cloudy day. I also added a heater strip to prevent freeze up which has burst tubes twice even with 2 thermal drain valves.