Heater Bypass for 390 Sundancer

Boater13

Boater13

Member
Jun 29, 2021
36
Midland Ontario
Boat Info
2005 Sea Ray 390, blue hull, Axiom GPS, Merc 8.1 HO, bow thruster
Engines
Merc 8.1 HO shafts
Has anyone installed a bypass for the heater on a 2005 390?
I order a bypass kit from Amazon (Camco), but could not figure out how to install it.
Seems like I would need several other connectors.
 
in my situation, TWO of these allow me to isolate the cockpit heater for now.

Four Seasons 84706 Shut Off Valve + Free Shipping (amazon.com)

When the weather cools, I'll replace the 26 year old mile of coolant hoses running to the helm.

I also installed a pair of these on the coolant hoses running to the hot water tank,

The purpose of all of this is the ability to shut off those circuits from the cooling system, SHOULD THE NEED ARISE.

BEST !

RWS
 
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In a 390? No. But the boat model isn't important. All that matters is the heater. Yes, like others, have done this. There are different kits available.

But... you have a hot and a cold fitting on the heater. All you're doing is connecting the two lines (hot and cold) together. In reality, this could be as simple as removing the two lines and duct taping them together. That's the idea - you can get as fancy as you want. Hopefully that explains it better so you understand the "goal" - how you actually go about it can be done a few different ways - often dictated by the type of connections your particular heater lines have.

If you still have questions, you may want to post some pics of your heater as we don't know what you're working with. And maybe the kit you bought, as well.
 
I ordered this one. Camco 35963 RV 12" Supreme Permanent By-Pass Kit for 10 Gallon Tank, Freshwater Systems - Amazon Canada. I returned that one.
In our climate, I prefer putting the pink stuff in to prevent freezing.
I looked at the heater again and I think I need to put a bypass valve at the point that water from the fresh water tank enters the heater. From that valve, i need a line to the cold water inlet to the heater and install a bypass valve and a 'T' . Then I need another line from the T to another bypass valve to the hot water inlet.
 
Boater13 said:
In our climate, I prefer putting the pink stuff in to prevent freezing.
I looked at the heater again and I think I need to put a bypass valve at the point that water from the fresh water tank enters the heater. From that valve, i need a line to the cold water inlet to the heater and install a bypass valve and a 'T' . Then I need another line from the T to another bypass valve to the hot water inlet.
Click to expand...
This isn't making sense. You said "I need a line TO the cold water inlet". There is only one. The line from the fresh water tank IS the cold water inlet.

As I noted above, there are multiple ways to do this. BUT, the kit you bought will work. The valves install on the tank nipples and can be turned to select what you want to do... Either allow cold water in and hot water out or turned to bypass the heater.
 
If you're using the Camco kit I referred to earlier, you will probably need a couple of fittings to adapt your existing lines to the new valve and tee. Maybe. Looking at the image on the package, you end up with two male pipe fittings to connect to.
upload_2022-9-25_10-47-9.png
 
Sorry. Meant outlets not inlet.
There is the main water pipe from the tank and the 2 outlets. One hot and 1 cold.
 
Boater13 said:
Sorry. Meant outlets not inlet.
There is the main water pipe from the tank and the 2 outlets. One hot and 1 cold.
Click to expand...
There is no cold water outlet. You may be confusing the expansion valve with a cold water outlet? The cold water line should branch off before the heater to the rest of the boat. No different than the hot water heater in your home - take a look.
 
Your boat is only 1 year newer than mine. Do you have the red and blue pex? Maybe just pull the red and blue lines out of the water heater and connect them together. In the spring when you plug them back into the tank, you'll have a couple spare 90's for your goodie box, should you need them. Easy.

IMG_E1406.JPG
 
I do not have the cold water branch off before the heater. One major line into the heater, one blue and one red out to the distribution panel respectively.
I will go to one of the plumbing places and get a temporary custom bypass that I can use and when done remove.
Thanks to all for providing input.
 
I think if you look closer, you'll see it's different than what you're thinking. The black hose is your expansion valve. The blue line comes FROM the manifold to feed the heater. I'm only reiterating this because it's good to know how things are plumbed for future reference.
 
Oh. Thanks. I will check again when I get to the boat next.
 
It'll make more sense once you look things over a little closer.

Now, since you have the red and blue lines with slip connectors, obviously the kit you bought won't work. BUT, I believe you can get the same style of 3-way valves through a place like Fresh Water Systems, but instead are meant for slip connectors. You'll want to double check your parts manual (or measure/look at your plastic lines) but I think you'll have 15mm lines as opposed to 1/2".

But, you could just slip a short length of old garden hose over the (removed) blue and red lines and use a couple worm gear clamps. That will work just as well.
 
I disconnected the supply line from the heater and connected it directly to the hot water connection on the manifold, therefore bypassing the heater. After winterizing, I reconnected the line to the heater and flushed it with antifreeze. Ready for winter.
Thanks for your input.
 
Boater13 said:
I disconnected the supply line from the heater and connected it directly to the hot water connection on the manifold, therefore bypassing the heater. After winterizing, I reconnected the line to the heater and flushed it with antifreeze. Ready for winter.
Thanks for your input.
Click to expand...

Did the blue/red/black lines make more sense once you got there and put eyes on it again?

If you're comfortable with what you did, then fine. But I'm not following what you wrote. The "supply line from the heater" is ALREADY connected at the manifold. The supply line FROM the heater is the hot line.

The point is to connect the hot and cold lines (at the heater) together so you can winterize all of the lines in the boat.

The heater, itself, only needs to be drained to protect it for the Winter. It does not (and really, SHOULD not) have antifreeze pumped into it. Plus, if you didn't first drain it, you are left with some sort of mix of water and AF in there.
 
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I’m not quite following that either but if you’re good with it, you’re good with it.
Sometimes there are variations to how things can be plumbed up on these things and sometimes pictures are worth a look.
This is my water heater as it will sit all winter.
8B51B9C2-333D-4A3D-9136-4E8F5ADEA2C7.jpeg

blue line is cold water in.
Red is hot water out.
I pull them out of their fittings on the tank and connect them together with that red jumper. That bypasses the tank and the pink runs through all the hot water lines and faucets via that connection.
Yellow arrow is the pressure relief valve, toggle it to the open position so any trapped water is not held in the valve.
Green is a hose I connect to the tank drain valve to route the water to the bilge. Open that valve and let all the water drain out of the tank. (Most guys just open the valve and let the water run out, it’ll find its way to the bilge pump eventually but I don’t like everything getting wet on the way so I use the hose) I do not put pink in my fresh water tank or hot water heater.
The 2 hose connections that are circled in orange are ports to connect to one of the engines coolant circulation system to use engine heat to heat the water heater. Not usually used on boats that have a generator.
Just the way I do it. Ymmv
 
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