Originally Posted by yachtbrokerguy
Fred, I have not seen an over temperature shut down on a main engine, yes on almost all generators but not mains. I have always been told it was a safety issue. The surveyors concern was not air conditioning, water maker, or other auxillary systems but a very expensive main that could overheat.
I agree with valves on heater systems plumbed to main engines. Most of the pics posted on this forum show heaters adjacent to the engines where the plumbing gets inspected routinely. In many cases the heaters are remotely mounted where they may not receive routine scrutiny. Especially by paid help.
I don't recall who makes them but there are water heaters built that have aluminum nipples for the engine heat side. I have found at least six of these plumbed to raw water cooled gas engines. One of these units failed when I tugged lightly on its hose to see around it. In another instance I found one leaking into an aft cabin area unbeknownst to its owner.
There are more atypical boat owners on Trawler Forum than you typically find in this business on a day to day basis. When you work with most folks who aren't up to speed and see their remotely mounted water heater (not in the engine room) is connected to there $40,000 main propulsion diesel and they never leave the dock without their generator running what would you suggest... Oh yeah, the engine heater circuit line is plumbed with reinforced clear plastic hose rated for a maximum working temperature of 130 degrees F!