Check valve needed?

[mregan]

I'm replacing all the plumbing on the boat.  There is a check valve from the galley sink drain to the thru hull.  My C-30 never had a check valve and I never had any water flow issues.  Is the check valve needed?

[Exodus]

Are you sure that line does not go from your icebox drain to your sink drain?  If so, yes it is needed.  I did not have a check valve on my boat and was experiencing backflow into my icebox.  The plumbing schematics show a check valve there, so I replumbed with a check valve and problem was solved.

That is the only check valve that I have under the galley sink and the only shown in plumbing diagram.

[Ron Hill]

mre : As Exodus said "There is only one check valve under your galley sink (installed by the factory)". 
If you look in your owners manual on about page 4.3.3 you can see the plumbing diagram with the check valve on the hot water line clearly marked.

A thought

[mregan]

Thanks.  I was at the boat today and you are correct.  Check valve is from the icebox drain.  I have a line from the icebox drain to the foot pump.  Then a line from the foot pump which tee's into the sink drain.  There is a check valve in the foot pump to galley sink drain line.
There is also a check on the hot water line from the water heater to the galley sink/head sink tee.  Is this one not needed?

[Exodus]

Hmm, I don't think I have one on the hot water line.  I notice Ron mentioned the hot water line above as well.  I believe that the foot pump may have been an option so all boats may not have the check valve for the ice box drain.

I will have to take a look at my hot water line when I get back to the boat, but if the check valve is there I certainly would not remove it.

[Mike and Joanne Stimmler]

mre,
As Ron mentioned, the checkvalve on the water heater is in the owners manual and should be kept. I believe it keeps the hot and cold water from backfeeding. The check valve on the ice box drain keeps water from the sink drain and the thru hull from getting into the bottom of the ice box. I think the bottom is actually below the water line. Mine always got clogged so I replaced it with a cheap plastic ball valve from Ace hardware and just opened it when I needed to pump out the ice box.

Mike

[Ron Hill]

Like Mike I replaced my one way valve in the fridge drain to a ball valve as I also have the foot pump plumbed so it can also pump fresh water (in case the 12v pump were to go out!)

A thought