Used one with my Judson, 4HT and propane engine too, for 5 yrs. Only problems I ever had wasthe jets plugging because of the ocean air here. The beauty of it was all it required was water flow and it would turn on. And it would shut off when it got hot. Never over heated, unlike my exhaust hx. I only stopped using it because BC regulations changed and running propane was going to be a real pita. Just servicing the propane engine took an all day trip to the mainland.
Anyone remember the van that blew up from the coolant/exh hx'rs. I can't remember what happened but they darn near took out the entire front end of the van!!