Can you Damage a Water Heater by Leaving it on Shore Power ?

[Hugh Walker]

When we bought our boat (2009 Beneteau Oceanis 46) the broker specifically told us that when on shore power don't leave the hot water on for more than about 30mins or risk damaging it, they also ran charter boats so I gather this advice came from their own experience but we never really asked why. Has anyone else been told this? It doesn't make sense to me, the hot water is a modern system (Quick B3 30L) with a thermostat... what could go wrong???

[St. Elsewhere]

That sounds strange. You can damage the heating element if you run it with no water in it. But if it is full of water, it should be able to be left on. The thermostat regulates the temperature within safe limits.

Anybody know if this product has experienced defective thermostats?

Nothing in the specs tells you to shut it off after 30 minutes: http://www.quickitaly.com/?lng=us&ms...1&cs2=1&stp=ps

[peghall]

Two probable explanations for that bit of misinformation: charterers who routinely ran the water tank out of water, and therefore the hot water too....or the broker's only experience was a water heater that had a defective thermostat or it was turned on and left on when there was bleach or antifreeze in it (both of which will destroy the heating element and the thermostat).

My own water heater was occasionally left on for a week, never had a problem even though it was more than 10 years old.

[sailorboy1]

wonder what that broker does with his water heater at home?

[David M]

If it can destroy itself like that then it is a case of bad engineering and not your fault if it does destroy itself.

[sailorchic34]

As others have said, as long as there is water in the tank it will work fine. Many Liveaboard water heaters are never turned off.

Oh I only turn mine on for an hour or so, but thats because I'm Cheep... Er... that is Furgal and like keeping the electric bill lower. But from an operational standpoint under normal operation its fine to leave it on.

[Bash]

Originally Posted by Hugh Walker

When we bought our boat (2009 Beneteau Oceanis 46) the broker specifically told us that when on shore power don't leave the hot water on for more than about 30mins or risk damaging it, they also ran charter boats so I gather this advice came from their own experience but we never really asked why. Has anyone else been told this? It doesn't make sense to me, the hot water is a modern system (Quick B3 30L) with a thermostat... what could go wrong???

Most modern marine water heaters are UL approved. They will have a heating element designed to withstand accidental operation in an empty tank. They will also have an overpressure relief valve, similar to home heaters. Mine also has an anti-scald device.

The good news is your broker has no idea what he's talking about. The bad news in your broker has no idea what he's talking about.

[Hugh Walker]

Thanks everyone, I've one less thing to worry about now