1989 340 Sundancer: Check valve for fresh water system location?

carboncow

Member
Jul 25, 2014
55
Ohio
Boat Info
1989 340 Sundancer & 2007 Sea Doo Challenge 180
Engines
Mercruiser TbIV 454ci V-drive % Rotax 4stroke 215HP
1989 340 Sundancer

Hello, noting that my cold water when hooked up to shore water is not that cold, luke warm. I'm guessing I'm getting some back mixing from the hot water tank.

Any ideas where I'll find the check valve that may be causing this mixing? Haven't popped the hatches yet to look around so hoping someone can save me some time when I get into after the labor day weekend.
 
carbon, the water that comes through the plumbing on the docks will likely be the same temp as the ambient air. Those pipes generally run beneath the docks, but not in the water, so the water in their would be the same temp as the air temp.

We run into the same thing out here and our air temps are usually in the 90's. For that reason I never hook up to city water. I fill my water tanks and that tends to stay cooler because the tank is low in the boat and will be closer in temp to the water temp than the air temp.

Also, when you are hooked to city water, be sure to turn it off when you leave the boat. If the city water should get a pressure spike it could blow a connection on your boat. If that happened you would have a flood of city water that the bilge pumps could not hope to keep up with. It wouldn't take too long before your boat could sink right at the dock.
 
carbon, the water that comes through the plumbing on the docks will likely be the same temp as the ambient air. Those pipes generally run beneath the docks, but not in the water, so the water in their would be the same temp as the air temp.

We run into the same thing out here and our air temps are usually in the 90's. For that reason I never hook up to city water. I fill my water tanks and that tends to stay cooler because the tank is low in the boat and will be closer in temp to the water temp than the air temp.

Also, when you are hooked to city water, be sure to turn it off when you leave the boat. If the city water should get a pressure spike it could blow a connection on your boat. If that happened you would have a flood of city water that the bilge pumps could not hope to keep up with. It wouldn't take too long before your boat could sink right at the dock.

Thanks for taking the time to comment...many good points but I still need an answer to my question. This happened on a previous boat 10+ years ago and I'm quite sure it's the same issue.

Although our water runs under the dock too and it's been warm if you feel the water at the spigot it's very cold...but in the boat luke warm.

PS. Had a holding tank only in our 3100 Tiara Convertible...it was a pain in my opinion to fill, clean, manage...fine with city water in our area!
 
There is a check valve right on the hot water tank. It's the longer fitting on the inlet side. If there's not one that I suggest you purchase one if you feel that you're back feeding. It's a tight fit but you can take the back small engine access panel off if you need a good look at it or you can just use the port side panel where the battery bank is located. Hope that helps...
 

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