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Old 14-08-2013, 13:02   #1
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Yanmar 3GM30F Removing Hot Water Heater

Hola,

I see people talking about adding a hotwater heater, however I want to get rid of mine. Since living in the Keys I've found absolutely no use for a hot water heater and would like to use the space for other things.

There are two hoses coming off the front of the engine. I'm assuming one going to the water heater and one returning to the engine. I've also found there is a 3/8 plug in the parts diagram that I can put in place. Is there more to removing this old rusty thing than disconnecting both hoses and plugging them? Do I need to complete a circuit or am I just plugging both?

Just making sure before I saw zaw this old tank


Thanks
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Old 14-08-2013, 13:04   #2
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Re: Yanmar 3GM30F Removing Hot Water Heater

Plug 'em.
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Old 14-08-2013, 13:10   #3
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If you plug both how would that affect water flow through the engine?

I would complete the circuit with a short hose.
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Old 14-08-2013, 13:22   #4
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Re: Yanmar 3GM30F Removing Hot Water Heater

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If you plug both how would that affect water flow through the engine?

I would complete the circuit with a short hose.
If anything, more water will flow thru the engine.

The engine comes from the factory with plugs that you remove and connect the water heater to the low side and high side of the pump. The water heater is then paralleled with the flow through the engine. There is no short hose from the factory, so why would you put one there?
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Old 14-08-2013, 13:37   #5
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Re: Yanmar 3GM30F Removing Hot Water Heater

Dot dun is probably correct but I would run the short hose if I was doing it on mine. 4jh3te on my cat.
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Old 14-08-2013, 15:27   #6
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Re: Yanmar 3GM30F Removing Hot Water Heater

This is a great example of BS advice on the internet. Two for plugging and two for bypassing. Who is right. I know what I would do ;-).

David
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Old 14-08-2013, 15:46   #7
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Re: Yanmar 3GM30F Removing Hot Water Heater

No one is "right" or wrong, either works.
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Old 14-08-2013, 16:11   #8
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Re: Yanmar 3GM30F Removing Hot Water Heater

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Originally Posted by djmarchand View Post
This is a great example of BS advice on the internet. Two for plugging and two for bypassing. Who is right. I know what I would do ;-).

David
If I cared enough, I would walk the 40' to my boat and take/send pictures of my (2) 3GM30F engines, one that is connected to a hot water heater and one that is not connected to a hot water heater.

I answered the question that was asked. Those that haven't a clue are questioning my answer. I don't really care what they do/say, nor do I care what the OP does enough to expend the energy to prove my answer.
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Old 14-08-2013, 17:55   #9
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Re: Yanmar 3GM30F Removing Hot Water Heater

Well the fact that they sell both plugs kinda makes me lean towards plugging both. I also think adding a hose is a point of failure and if plugging them won't cause an issue I'd prefer that route. I'm going to go with plugging.. The threads I did read about installing a water heater mentioned it decreasing the flow, so it would make sense plugging it would increase. Won't be for a couple days but I'll keep following along, for now plug is the answer until I read something definitive.

Thanks guys!
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Old 14-08-2013, 19:35   #10
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Re: Yanmar 3GM30F Removing Hot Water Heater

As mentioned, either way will work. From a strictly engineering standpoint, pulling the hoses off the engine will allow all the water to recirculate through the tank so heat rejection will be somewhat better.

With the hoses kept with a loop, a small portion of the water is recirculated in the loop and the thermostat responds by opening more.

Plugging unused hoses allows a bit more reserve cooling, so its preferred, from a strictly engineering standpoint.
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Old 14-08-2013, 20:18   #11
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Re: Yanmar 3GM30F Removing Hot Water Heater

All fine, as long as there is not a separate header tank included in the heater circuit. See the current thread:
SailNet Community > Boat Builders Row > Pacific Seacraft > Removing Hot Water Heater
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Old 14-08-2013, 21:14   #12
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Re: Yanmar 3GM30F Removing Hot Water Heater

The surge tank in the Pacific Seacrafts is installed for the water heater, NOT for the engine. So removing water heater, surge tank, hoses, etc. is just fine. And yes, if you have plugs, put them in.
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Old 14-08-2013, 21:29   #13
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Re: Yanmar 3GM30F Removing Hot Water Heater

Is this for Yanmar only where you plug the lines or is this across the spectrum of diesels. I have a Volvo MD30A and have the same question.
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Old 15-08-2013, 05:38   #14
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Re: Yanmar 3GM30F Removing Hot Water Heater

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Is this for Yanmar only where you plug the lines or is this across the spectrum of diesels. I have a Volvo MD30A and have the same question.
I have no experience with your particular engine, but it's the same on every engine I do have experience with.

Think about how the cooling system works, it makes no sense to do it any other way!
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