Hot Water Tank Installation on a 91 2655-gctid383989

[Guest]

Hi All,

I will be installing a Seaward F600 (6 gal) hot water tank and have a few questions (Please see attached photo and installation manual):

In the attached photo the water lines on the left that is connected with tees is what the previous owner did after removing the original water tank.

Questions:

1. The fittings on the tank are clamp style while the boat uses NPT pressure fittings. I doubt I can use a clamp on that style hose, can I get NPT fittings to go on the hot water tank or do I get clamp style fittings to come off the waterlines tees.

2. Where can I buy these type of plumbing connectors and hoses in Canada, do they carry them at the big box home reno stores?

3. Lastly the installation manual is pretty vague and in the diagram to connect it through the engine using a heat exchanger, I can't tell where the coolant lines coming off engine? Is it off the thermostat?

Thanks in advance for any assistance, BOC has been a great resource for me and I try to contribute when I can.

Cheers

Attached files [img]/media/kunena/attachments/vb/687513=27920-Hot Water Tank.jpg[/img] [img]/media/kunena/attachments/vb/687513=27922-Seaward Water Heater_Page_5.jpg[/img] [img]/media/kunena/attachments/vb/687513=27923-Seaward Water Heater_Page_6.jpg[/img] [img]/media/kunena/attachments/vb/687513=27924-Seaward Water Heater_Page_7.jpg[/img]

[Guest]

One hose to the heat exchanger on the HW tank should come from the coolant source on your intake manifold. If you look, you might see a plug that will serve this purpose. The other connects to the side of your engine coolant circulation pump on which there will definitely be a plug. I used barbed brass fittings with heater hose and hose clamps for these connections.

[Guest]

I here crickets on this thread, with the exception of mainecoast's response which I got through email but does not appear on the this thread.

I take it not to many have installed a water tank.

Anyway I did some research and discovered that the Mercruiser engine manual has a section on how to connect the heat exchanger, so I'm golden.

[Guest]

Surprised you got the message via email. I found that I was babbling and deleted it......

[2850Bounty]

love2speed wrote:
3. Lastly the installation manual is pretty vague and in the diagram to connect it through the engine using a heat exchanger, I can't tell where the coolant lines coming off engine? Is it off the thermostat?

This engine plumbing connection will be incorrect for your V-8 application.



The WH engine coolant supply will be just ahead of the T-stat housing in the intake manifold.

If GM SBC, the Starboard-most port on the engine circulating pump will be your coolant return.

Connect this way, and your system will be balanced (I.E., mild pressure from the thermostat holding back coolant......... and mild suction from the circ pump.)

The WH doesn't care which engine coolant port is supply or return.

It's simply a coil loop within the potable water side.

.

Attached files http://baylinerownersclub.org/media/...em 2.jpg[/img]

[Guest]

Thanks everyone,Maincoast I'm glad you chimed in it got me thinking and digging deeper for info.2850Bounty thanks for the info, everything clicked when I saw your response.lastly this is what the Mercruiser Manual had to say.Basically the only thing I'm still foggy on is how to connect the water supply lines from the boat plumbing, as mentioned they are NPT pressure fittings so I guess I will just get a fitting that is barbed on the one end and just use plumbing hoses and alligator clamps, similar to the heat exchanger

[img]/media/kunena/attachments/vb/688782=28105-25-05-2012 3-20-31 PM.jpg[/img]

[2850Bounty]

First..... a good Technical Writer would call this "coolant"... not water!

Secondly.... the supply will be ahead of the thermostat..... not after the thermostat nor in the T-Stat housing!

They did get the Circ Pump return correct!

Like said.... if you want a balanced system, use the ports that I have suggested.

As for the potable water side.... there will be an IN and OUT to this. Plumb it accordingly!

.

[Guest]

I'll apologize in advance for a stupid and unnecessary comment and question. I have a '90 2755 and it did not come stock with a closed cooling system nor did the original water heater have a heat exchanger.

If I'm interpreting what you said correctly, the previous owner of your boat removed the water heater and plumbed around it.

You are now installing a new water heater with a heat exchanger so your boat must have come stock with a closed cooling system or somewhere along the line a closed cooling system was installed? Just trying to understand the existing set up.

[2850Bounty]

MikeRoss wrote:
I have a '90 2755 and it did not come stock with a closed cooling system nor did the original water heater have a heat exchanger.

If I'm interpreting what you said correctly, the previous owner of your boat removed the water heater and plumbed around it.

You are now installing a new water heater with a heat exchanger so your boat must have come stock with a closed cooling system or somewhere along the line a closed cooling system was installed?

Mike, since love2speed used page 6A-23 of the Merc data, I can only assume that his engine is raw water cooled..... not closed system cooled.

Here's the raw water cooling T-stat housing that he shows. (see below)

This housing does not work for a closed system.... only with the open system.

The WH will have a Heat Exchanger within it as well.

However, it's nothing more than a coil loop that allows engine coolant to flow through it, exchange heat with the potable water, and then return the engine coolant to the engine Circ Pump.

FYI: whether an open or closed engine cooling system, the WH or Cabin Heater coolant plumbing is the same.

Intake manifold prior to thermostat = supply

Stbd-most Circ Pump port = return

Attached files http://baylinerownersclub.org/media/...sing.jpg[/img]

[Guest]

Rick, correct me if I'm wrong on this, I thought that I remembered seeing an advisement against using a water heater heat exchanger with raw water cooling since a connection break would result in the engine pumping raw water directly into the boat, perhaps for an extended period of time before being noticed and without the warning of the engine temperature rising.

[2850Bounty]

That is true, although I think we'd see an engine temperature change one way or the other pretty quickly.

Whenever we add a WH to an "open" cooling system, there is that risk of corrosion within the aluminum WH coil loop.

Cabin Heater cores are brass or copper, and will usually hold up.

It also adds yet more more winterizing concern.

.

[Guest]

I just don't think I would use the heat exchanger without a closed system. I know that many do so without concern or problems so I'm probably being far more cautious than necessary.

[Guest]

sorry to just respond, I have a raw water system and have decided for the time being to just hook up the HW tank with electricity. In the next few years I plan on doing longer over night trips where I think this would be more suitable to have it also hooked up to the heat exchanger.

[Guest]

Flawless Installation

Hi All, just reporting back that this install went perfect. It turns out that the existing plumbing on my boat is 1/2 inch PEX which I easily outfitted with Sharkbite connectors, first time using these and they are amazing, push on and no leak.

Thanks for everyone's input.

[2850Bounty]

So did you end up using the WH coil loop for engine supplied heat?

You are in Ontario, Canada, so your water is fresh water. The corrosion issue still exists....., but no where near as what it would be with salt water.

.