Day Tank Size?

[Oceansailor]

Hi,
I'm considering installing a day tank to my Yanmar 4JH4-TE. (75HP)

I normally cruise at 7 knots and use 1.2 US gallon/ h.

My idea is to always use the day tank when motoring.

My generator will always draw fuel from the "storage tank" (100 gallons)

I have a manifold that makes it possible to use the the generator fuel supply for the engine in an emergency.


What is the miniumun size for a day tank with regards to heating up the fuel?

My tank will be around 25 gallons.

As I have two possible fuel supply for the engine I need to switch the return when going in emergency mode and take fuel directly from the storage tank.

Is there a foolproof manifold that switches both functions at the same time?

What filtering is suggested?

Between the storage tank and the day tank? Have in mind that the filters will also be used for fuel polishing.

Between day tank and the 10 micron on- engine filter?






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[Allan S]

Wow, I like your way of thinking! You remind me of my Navy days where we had 5 different ways of getting fuel to the engines

Would a simple 3 way valve answer your supply question?

As for fuel filtration, both my suppy side and my fuel polisher use a 10 micron particulate filter and a 2 micron water separator.

[GordMay]

A 6-Port Fuel Valve:
Supply and return lines are switched simultaneously, and the fuel is returned to the same tank it came from.
Port 1 - FROM Tank 1
Port 2 - FROM Tank 2
Port 3 - TO Engine
Port 4 - FROM Engine Return
Port 5 - Retrun TO Tank 1
Port 6 - Return TO Tank 2

Grocco #FV-65038A
➥ Untitled Document

➥ http://imcomarine.com/cal_store/medi...%20Diagram.PDF

[Allan S]

Gord's answer is more awesome

[Jaxxiam]

Grocco #FV-65038A
http://www.groco.net/00-scks-valves/fv-6-port.htm

Nice Valve!

[Oceansailor]

Gord,

Thank you so much for that information. It would work great in my case.

I did not know that such valve was available.

Alan, thanks for your input.

I would think a multistage filtering system between the storage tank and day tank would work.

10 micron and then 2 micron. What I do not understand why you would have the waterseparator on the 2 micron?

Would it not be better to have the 10 micron and a water separator. Why wait to filter out the water. After that a 2 microm filter in to the day tank.

Then after the day tank to the engine a 2 micron with water separator.

That would, I think be a bullet proof system?












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[Greenhand]

I am so getting one of those to cleanup the tangle of fuel lines left when a previous owner installed a day tank!!


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[Oceansailor]

Originally Posted by Greenhand

I am so getting one of those to cleanup the tangle of fuel lines left when a previous owner installed a day tank!!


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Documentation is everything. If you do not have that it all systems can be confusing.

There will be more fuel lines with a day tank, no doubt about it. My reason for posting my question was to limit the number of valves. If you have to turn more than one valve there is always a risk for mistakes.

But I do not like systems that requires turning 2 or 3 valves to get it right. This was my main reason.