Running engine with empty water heater

[Ken Juul]

Changing home ports this spring.  The time line to avoid paying at 2 marinas has me moving the boat in March.  I'm not sure if I will be able to get the water system un-winterized before the  move because the water on the dock ususally isn't turned on till April.  Will I cause any damage to the hot water heater by running the engine with it empty?  My guess is no, but there is that nagging saying about assuming things.

[Roc]

Ken,
I seem to believe seeing on the Seaward owner's sheet that you should not operate the engine with an empty heater.  It's like putting an empty pyrex decantor on your stove with no water in it to boil.  The pot will crack.  I believe inside the water heater is a glass tank.

Roc-

[Ted Pounds]

I run mine twice a year with an empty water heater.  Once to the haulout and once after launch.  I don't run it for very long as it is only about a mile from the travel-lift to my slip.  So far, after 8 years it hasn't caused any problems.

Ted

[Ray & Sandy Erps]

The water lines that go to the hot water tank from the engine will be running around 160 degrees whether there is water in the water tank or not.  The water tank is designed to hold hot water.  Guess it will be holding hot air instead if it's empty.  I think conventional hot water heaters can have their heating element damaged if the water tank is empty, like someone already mentioned, but in your case, the heating element won't be activated and it will be only the waterlines from the engine that are warm.  My best guess is that it won't hurt the hot water tank, but you might leave the hot water spigot open to let some of the expanding warm air to escape.

[Ken Juul]

As a follow up I spoke with Seward last evening.  They confirmed that it should not hurt the tank, also suggested opening a fawcet so the high pressure valve doesn't pop.  Hopefully I'll have some wind, looks like about 45 nm between marinas..long way to motor.  I think I'll be on the safe side and get the tank filled somehow.  Thanks for the inputs.