Water tank heater using engine coolant

[Eli27]

Just curious, if I don't have water in the tank will the heating element be ok in the tank while engine is running?

 

[tiltrider1]

Having no water in the water heater tank will not affect the engine coolant loop. However, do not turn on the electrical heating element if the tank has no water in it.

 

[Comodave]

We bought a boat that had an empty water heater. I heard a sizzling noise in the engine room. It was the water heater element sizzling. Apparently the PO had left it on when he put the boat up for sale. It had been on for several months without water in the tank. I assumed that I would have to replace the element but it was still working great when I sold the boat 8 years later.

But the hot coolant from the engine should not hurt anything with the tank empty.

 

[sunchaser]

Just curious, why run the coolant loop if the tank is empty? Just close the on engine coolant loop valves.

 

[Eli27]

Just curious, why run the coolant loop if the tank is empty? Just close the on engine coolant loop valves.

I've been getting boat ready for water, splashing monday am. Not gonna have the water system 100% and there are no valves. I'm taking boat from Newburyport MA to Providence RI. Hopefully just a 2 day trip.

By the way, boat is new to me. Whatever systems I have running I want to know the ins and outs. Really the only systems I'm concerned with is propulsion, steering, and nav. Nothing else,,,, for now. What's I'm home I can get the rest done.

 

[sunchaser]

Eli
When you've got time install the coolant loop shut off valves. This prevents loss of coolant where you'd never see it. With a full hot water tank under pressure at least the coolant couldn't escape the engine whereas with an empty tank a leak in the tank loop would result in an engine over heat.

 

[DDW]

If the coolant escapes into the domestic hot water tank, you have a potentially lethal situation, not just and inconvenience or overheating engine.

 

[O C Diver]

If the coolant escapes into the domestic hot water tank, you have a potentially lethal situation, not just and inconvenience or overheating engine.

While there is a risk, most boat domestic water systems operate at 3 to 5 times the release pressure of expansion tank cap. The freshwater would be forced through the engine's coolant loop. Most engines expell less than a quart of coolant as the engine warms up. So the coolant concentration would be under 3% in the water heater. Most people don't drink from the hot water faucet.

Ted

 

[sunchaser]

OC
The OP’s water tank was stated as empty

 

[O C Diver]

OC
The OP’s water tank was stated as empty

Yes, I understand that and would recommend that he close the loop valves on the engine. But, it's still not likely to be a potentially lethal situation.

Ted