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Keep water heater drained

Hagar2sail

Member III
Blogs Author
This might be a dumb question, but is there any reason why I can’t keep my water heater bypassed? We really don’t motor enough for it to stay hot and are on a mooring all the time so no shore power. Seems like it is easier not to connect / disconnect and drain it each season, but didn’t know if there was any issues with the hot engine coolant going through an empty hot water heater!
 

Afrakes

Sustaining Member
Disconnect

Disconnect it entirely and there will be no concern with hot coolant circulating through the heater.
 

u079721

Contributing Partner
IIRC there is actually some wording in the manual suggesting that you MUST keep the water heater full of water to ensure proper cooling of the engine. Which is just silly, since the water within the heater would cease to absorb any additional heat once it too gets up to operating temp. We typically took a cruise every August, meaning that at first all May, June, and July we warmed the water within the water heater while not using any of it to bath or do dishes. With the result that the water went skunky each summer by the time of our cruise. So we stopped filling the water heater with water and rigged a bypass tube, and used it that way all summer till right before our cruise. Worked great. No engine overheating, and no skunky water.
 

toddster

Curator of Broken Parts
Blogs Author
I would think that the only issue would be whether the HX could withstand the heat in the circuit without the sink of the house water. And that only lasts until the reservoir heats up anyway. But a call to the customer service line of the heater manufacturer might be easy.

It might be because I have a small heater, but I’m actually very pleased with how fast mine heats up, and how long it remains usefully warm in the evening. I’m keeping it in action.

If one wanted a bypass valve for the fresh water supply, it would be trivial to add another identical bypass for the engine coolant. If one wanted to get elegant about it, six-port valves are available, so you could do it all with one stroke.
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
IIRC there is actually some wording in the manual suggesting that you MUST keep the water heater full of water to ensure proper cooling of the engine. Which is just silly, since the water within the heater would cease to absorb any additional heat once it too gets up to operating temp.

I also read this caution in the owner's manual, and it was a recurring discussion on the forum. I've had my tank diconnected from my engine FW cooling for two years now.

As to the warning in the manual? I think, "Don't turn on the electric heater elements without first filling the tank," got dumbed-down to, "Don't heat the tank without first filling it," which further for dumbed-down to, "Don't run the engine without first filling the water tank."

Which, like you say, sounds just plain dumb in its final form. But maybe Ericson learned over the years that as soon as you idiot-proof something, along comes a better idiot.
 
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Afrakes

Sustaining Member
Optional

My manual states that the water heater was an optional piece of equipment. It's not needed to operate the engine.
 

Tom Metzger

Sustaining Partner
Seaward Products water heaters have no warning about running the engine without water in the tank. The current version warns about turning on power when empty, but also has a thermal breaker to prevent burnout with instructions for resetting it.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Do not worry.....

My manual states that the water heater was an optional piece of equipment. It's not needed to operate the engine.

Right on.

I actually paid a little bit extra to have the connections added to our new diesel last year to enable plumbing to a water heater coil.
Our diesels run at 165 to 180 degrees F.
This does not harm any of the designated reinforced hoses or metal tubes in the system including the metal inside the HE, that contain the coolant mixture.

This can be described as 'mature technology', and pretty basic.

So do not worry about whether the coil inside your hot water tank is submerged in water or not.

OTOH, keeping the 110 volt AC heater element (when energized when you are on shore power) submerged in water is Vital ! :0
 

u079721

Contributing Partner
......So do not worry about whether the coil inside your hot water tank is submerged in water or not.

OTOH, keeping the 110 volt AC heater element (when energized when you are on shore power) submerged in water is Vital ! :0

Good point. I should have noted that when I left the hot water tank empty for the first half of the summer I did keep the 110 V water heater switch taped in the off position - just to be safe.
 
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