[Archived]

G-Man,

Let’s address this as two issues, as they have two different solutions.

First, heating provided by the engine heat exchanger. Engine coolant can be way too hothot, especially with newer engines. Too hot for domestic hot water and too hot for the hot water heater. The engine coolant loop must have some type of flow limiter. CC installed an additional hot water thermostat that controls a coolant valve. Lacking some form of coolant regulation can cause the hot water heater’s temperature/pressure safety valve to open.

Most of the marine hot water heaters we have use a fixed thermostat set for 140 degrees. This is too hot to be passed on to our fixtures as it doesn’t take long to scald. Old school was to set hot water heaters to 120 degrees to reducd the scald risk. 140 degrees is required to kill bacteria, so 140 degrees makes since. All hot water heaters should be outfitted with a mixing valve. A mixing valve is a simple mechanical device that connects to the hot water output and cold water input. It mixes cold water with the hot water to limit the temperature of the water being supplied to hot water fixtures. Some mixing valves are temperature adjustable and others are fixed at 120 degrees.

If you can access your hot water heaters, a mixing valve should be an easy install. If you have 2 hot water heaters you only need one mixing valve.

[Dick]

We rented an 89 CC last year. The owner warned us that if we took shower after comming off the road the water would be HOT. He was right.

Our Liberty has a shower fixture lets me set the temp and it mixes hot with cold which solves that problem in the shower.

But putting the mixing valve at the water heater makes lots of sense for the faucets and clothes washer. Good idea.