Holding tank water is heated up?

[sailingsunshine]

Hello fellow boaters,
Me and my husband are new owners of a 1980 38 c&c landfall and we're slowly getting acquainted with our new girl. We just moved the boat out from the marina to a close-by anchorage, maybe 45 min of running the engine. We do know there's a water heater installed close by the engine under the cockpit and have used it once while in the marina (first time with a hot shower on the boat, what a dream come true) so we know it works great. After we moved to the anchorage, we went in to town to grab some things, maybe 4 hours tops. When we came back, I started the dishes, and the water came out wonderfully hot like our heater was on. I checked to confirm it wasn't, but can't think of how the water had heated up so much like that. We haven't investigated the plumbing all so much, but we are wondering if the previous owner has ran the engine cooling pipes through the water heater, and if anyone else has a similar setup or even a better explanation as to why my holding tank is full of hot water, it would be quite enlightening. Not saying I'm ungrateful, this is a wonderful find. We just want to make sure there's not something wrong going on!
Thanks for any input and happy sailing[emoji2]

BTW did want to say that no, the sun wasn't heating up our tanks, unless its able to get through 2 layers of fiberglass and balsa wood and get the water to a wonderful 90°

[Emmalina]

It will probably have the water from the cooling system piped through you hw tank!

[cal40john]

It is common to have the engine plumbed to the hot water tank as the post above.

Holding tank usually means sewage tank.

[Uncle Bob]

Originally Posted by Emmalina

It will probably have the water from the cooling system piped through you hw tank!

As it should. Water is heated as the engine runs.
By the way, the term holding tank is generally used to describe the tank that stores the effluent from the toilet.

[sailingsunshine]

Thanks all for the responses! This is great to know now and thats my bad. I've heard all sorts of terms for the water tanks, but waste tanks are always called holding tanks. My bad and I'm sure more thorough investigating will let us know more. Thanks again!

[peghall]

It's highly likely that your water heater not only has to rely on shore power, but also via a "heat exchanger," which uses heat off the engine. If you know the make/model of your water heater, you should be able to find the owners manual for it on the 'net. In it you'll find information about how a heat exchanger works.


Btw...the term "holding tank" only refers to the tank that holds toilet waste. I'm pretty sure that's not the tank that was delivering hot water to your sink...at least I hope not! I'm pretty sure it was the water tank, which has the unoriginal name "water tank."


--Peggie

[Dave Lochner]

Once the diesel gets to operating temperature, somewhere between 160° and 180° F, it likely heats the HW tank very rapidly.

The 6 gallon Raritan on my boat will keep the water warm for well over 12 hours.

[Stewie12]

The water tank that is heated by the engine is called a calofier, if I remember correctly.

[sailorboy1]

The hot water on my boat gets so hot from the engine loop that if we motored an hour that it was dangerous so had to install a mix valve.

But i really wanted to read about the holding tank heating up. That had beginning of a hot sh*t story.

[johnn33]

Perhaps this will help
https://www.sailboat-cruising.com/bo...er-heater.html
John

[Kd9truck]

Sunshine “good on ya”! Keep asking questions and soon you,ll be able to answer some. You will want to add this fluid loop to your “time to check fluids” list. If you are new to the vessel you should do a fluids swap out. there should be fresh anti-freeze in the loop at a 50/50 to water ratio, even if you are on the equator, the antifreeze loop is working like your automobile radiator without a fan. It will inhibit rust, make the cooling and heating more efficient, preserve the life of tank and motor.

Also do not use old style green anti-freeze, it is highly toxic and illegal in the US,(the green stuff has killed many a pet) Use the pink stuff.

[sailorboy1]

[QUOTE=Kd9truck;3301294

Also do not use old style green anti-freeze, it is highly toxic and illegal in the US,(the green stuff has killed many a pet) Use the pink stuff.[/QUOTE]

Its not illegal!!!! The green stuff is what you use for your engine unless you plan just corrode it out.

[Goodall_M1]

Originally Posted by peghall

It's highly likely that your water heater not only has to rely on shore power, but also via a "heat exchanger," which uses heat off the engine. If you know the make/model of your water heater, you should be able to find the owners manual for it on the 'net. In it you'll find information about how a heat exchanger works.


Btw...the term "holding tank" only refers to the tank that holds toilet waste. I'm pretty sure that's not the tank that was delivering hot water to your sink...at least I hope not! I'm pretty sure it was the water tank, which has the unoriginal name "water tank."


--Peggie

Ah but Peggie can't you get anaerobic heating generation in your holding tank if you don't dump it or get it pumped out?

Only kidding, (I just couldn't resist suggesting it!)

Happy Christmas everyone!

[gonesail]

Originally Posted by Kd9truck

Also do not use old style green anti-freeze, it is highly toxic and illegal in the US,(the green stuff has killed many a pet) Use the pink stuff.

either way .. you can't mix one color coolant with another

[Dave Lochner]

Originally Posted by sailorboy1

Its not illegal!!!! The green stuff is what you use for your engine unless you plan just corrode it out.

I bought some in NY just a few months ago. I use it to winterize the heat exchanger and seawater cooling system. It is kinder to the hoses and gaskets.