Mystery valves

[mncruiser]

Preparing to winterize my 2001 Mainship 390 in a few weeks. I came across this valve setup under the inside bed in the port berth, right by the water heater. Can anyone tell me what it is? Thanks

 

[Bacchus]

It may be a WH bypass for winterizing but you would have to check the connection points and diagram or photo it for anyone to confirm unless it is MS factory install and other owners can confirm. My guess is it is not OEM and was a previous owner mod unless all of your fittings are that type.

 

[AlanT]

Preparing to winterize my 2001 Mainship 390 in a few weeks. I came across this valve setup under the inside bed in the port berth, right by the water heater. Can anyone tell me what it is? Thanks View attachment 121815

Do you have two domestic water pumps to allow switching out a failed pump? If so this could be the bypass/selector valving to go from one pump to another. There would be a similar arrangement the other side of the pumps.

If not it is clearly switching water supply or source from the upper pipe to the one immediately below it. SO hopefully that give you a clue, and yes follow the pipe.....
~A

 

[High Wire]

Follow the tubing to see where it goes. It’s the only way to be sure.

 

[LongJohn]

My guess would be the ability to run dockside water pressure. But you'd have to prove it.

 

[kwmeyer13]

Without pictures showing where and how the lines are connected I am going with a hot water heater bypass for winterizing the system. It is very similar to what I installed. Bypassing the water heater allows the system to be winterized so you don’t need to fill the heater tank with “pink stuff”. All you do is open the drain valve on the hot water heater to winterize it, or should I say that is how I do it. Others may have different methods.

 

[Fogger]

Mystery Valves

For a 2002 390 Mainship, one of the valves isolates the port water tank and the other isolates the starboard water tank. As indicated in your picture, the water lines are identified with red and blue bands to assist in tracing back to the water tanks. There is no water heater bypass on mine. To drain the heater tank, there is a low point drain that will drain into the bilge. In conjunction with this drain, open the heater PSV for venting the tank.
Attached is a simple schematic I made for personal reference. Hope this helps some. John

 

[RT Firefly]

Greetings,
Welcome aboard.

 

[DrissZougari]

That setup can be used in multiple applications;
1- To draw water from individual water tanks similar to my setup on my MS390. If connected to fresh water pump.
2- To pump water to both ACs and specifically to winterize each system separately if connected to AC water pump.
It is not water heater bypass because of the valves configuration as far as I see it.
So will need to trace it to understand how it is used on your boat.
Good luck,

 

[Cartouche]

It may be a WH bypass for winterizing but you would have to check the connection points and diagram or photo it for anyone to confirm unless it is MS factory install and other owners can confirm. My guess is it is not OEM and was a previous owner mod unless all of your fittings are that type.

look to ne as sea Tech 1/2" fittings I know on my 390 they used 15mm not 1/2" and I just made a bridge to bypass the HWT disconnect in and out and connect together

 

[Cartouche]

For a 2002 390 Mainship, one of the valves isolates the port water tank and the other isolates the starboard water tank. As indicated in your picture, the water lines are identified with red and blue bands to assist in tracing back to the water tanks. There is no water heater bypass on mine. To drain the heater tank, there is a low point drain that will drain into the bilge. In conjunction with this drain, open the heater PSV for venting the tank.
Attached is a simple schematic I made for personal reference. Hope this helps some. John

No I disagree shut off for tanks is on the firewall behind ladder in ER at the Pump

 

[Fogger]

No I disagree shut off for tanks is on the firewall behind ladder in ER at the Pump

mncruiser - Since the original objective in this message string is winterization, I will add to this for further clarification. For my 2002, 390 MS, the valves in the original post picture are exactly what I previously described. There is also a valve in the ER as Cartouche described which is basically for isolating the "outside plumbing" for fore/aft showers, etc. Associated with this ER valve is another valve and drain line for winterizing this "outside water system" (washdowns, showers, etc). It's a bit quirky, but I guess if you were a liveaboard there is some value added with the setup. This is all identified in the previous sketch sent. Glad to further clarify. Hope this helps.

 

[Cartouche]

I guess they are all a little bit different these are the shut offs for the 2 tanks (on the bulkhead in the ER behind the stairs) the Manifold that controls each outlet is below the floor on the bulkhead below the lower helm. Ours is a seatech system that I thought they put on all 390's and 400's from 2000 - 2007

mncruiser - Since the original objective in this message string is winterization, I will add to this for further clarification. For my 2002, 390 MS, the valves in the original post picture are exactly what I previously described. There is also a valve in the ER as Cartouche described which is basically for isolating the "outside plumbing" for fore/aft showers, etc. Associated with this ER valve is another valve and drain line for winterizing this "outside water system" (washdowns, showers, etc). It's a bit quirky, but I guess if you were a liveaboard there is some value added with the setup. This is all identified in the previous sketch sent. Glad to further clarify. Hope this helps.

 

[Cartouche]

I guess they are all a little bit different these are the shut offs for the 2 tanks (on the bulkhead in the ER behind the stairs) the Manifold that controls each outlet is below the floor on the bulkhead below the lower helm. Ours is a seatech system that I thought they put on all 390's and 400's from 2000 - 2007

 

[Alaskan Sea-Duction]

Welcome to TF. Any chance you can contact the past owner?