Another "please help me" post on the potable water system

When I bought my Hatt, the potable water system was mostly disconnected. I've (attempted to) put everything back together and in the process replaced the expansion tank (broken bladder in old one), AC pump, check valves, GM pump. The AC pump short cycles rapidly untill it overheats and shuts down unless I have 3 or more faucets open at the same time, and then it runs like a champ. The new GM doesn't reach pressure and simply won't move water. I've bled as much air out of the plumbing as I can, checked for possible air leaks, moved pressure guages around, etc., etc.

If someone on the forum would be so kind, I would greatly appreciate some close up pics of the DC pump plumbing connections and maybe a sketch or detailed description of the system from the holding tank to the two pumps and expansion tank. I've got to assume that I just don't have something plumbed correctly.

Michael Ewing
Southern Comfort, 1977 Hatteras 58 YF
Chesapeake, VA

Keep in mind that the ac pump was NOT original so any plumbing associated with it was added. I have seen installations where folks put in ac pumps and used a series of valves to place the pump in/out of the water circuit. Others just put it in line with no other valves. It's hard to say what was done and therefore, how the plumbing circuit is set up now.

Also, depending on what the POs did re winterizing, there may be a series of fittings/valves that also were not original to the boat. So there could be valves that must be in certain positions for the system to function properly.

Our 53 has 3 valves/fittings between the tank and the pump - all located in the eng room that allow for easier winterizing I don't believe that any of them are original but I don't know that for sure. Two of them can totally shut off the water supply from the tank and allow compressed air/antifreeze to be directed to certain areas.

But fundamentally, there is just one hose from the water tank(s) to the pump intake. Have you tried just putting a bucket of water below the pump and running a piece of hose from the pump intake into the bucket to see if the pump (after priming) actually will move water?

I don't have any good pics of that portion of the eng room - at least good enough to show the various pipes but here is one taken when we initially looked at the boat that shows some of the system. DOn't know if it will help at all. Note that the hose from the tank comes from below the water heater, then above the top of the tool box. You can see the two fittings that allow "access" to the plumbing - one just above the left center of the toolbox (blue handle) and one below the 12v batt charger (red handle). Then there are two valves that can shut off the water suppy completely - one before the red handled access fitting and one after. If either of these valves are closed, no water will flow to the pump from the tank. Other than a new pressure tank and new hoses, the system is unchanged from them.

Mike,
I like the priming funnel attached to the GM pump. I have to pull the plug on mine. Nice addition.

Mike,
Thanks for the quick response and the information. The suggestion about trying to pump from a bucket of water was one of those 'well duh' moments for me! I got caught up in overanalyzing this situation and didn't think of the obvious. Thanks for the wakeup call. Next time you're back on the boat I'd appreciate a picture of the other end of the GM pump.

Check the air pressure in the bladder tank. It sound like it's ether to high or to low. Water logged or to much air pressure. Providing you have the system plumed correct. Both pump controls should see the bladder tank direct and each pump should have a back feed check. In order Pump, check, control, bladder tank, Tee, output.
It also sounds like the two pressure switches are not balanced. The low side of the DC pump switch will be set a little lower than the AC.


BILL

Does anyone know if that bladder in that accumulator tank is servicable. I've got to add air to mine about 4 times a year. Thx.

No it's not. However home improvement stores like Lowes and Home Depot carry them at less than what you would pay at any boating supply store (surprised?).

The recommended pressure is generally written on the side.

I should add that, for the sake of this thread, I have had dismal failure in attempting to salvage (meaning rebuild) a GM pump system. The 12V motor, though big as a diesel starter motor, was impressive. However the spiral squirrelly pump devise never would generate adequate pressure to satisfy minimum requirements (despite several phone calls to GM - so called - tech support). I wound up buying a big 12V (for my system) pump from a reliable N.C. marine supplier.

The old one is DOA. When I winterized, the whole thing was full of water. The new one is a "welltrol" from Menards for 39.95 ws

You should never have to add air to a bladder tank unless you change the working pressure of the system. It has got to be leaking air somewhere. 5 Years is a good count for years of service. Maybe you no longer have a working bladder in the tank. It's really not a bladder. It's just an air bag in the tank that you inflate. One pin hole and the system reverts back to the old conventional water logged tank where you must add air once or 10 times a year.

BILL

I'm sure it's original; 1989.....19 years isn't too bad. It doesn't owe me anything. But you just know the new will have a different mounting scheme, hole pattern, etc......was just trying to get lucky. Thx.

To check the bladder in a pressure tank, you will need to keep water pressure to the tank and then let the air out of the bladder through the tire valve. If you get water coming out, it's bad. If just air comes out until it stops, then drain your water pressure down and refill the tank with air to the cut-in pressure of your pump. You will then need to monitor the air pressure from time to time to make sure the valve isn't leaking. Those are the only two points of failure. Either it leaks from the valve or from the bladder into the water system.

Thanks for the insight on testing this. I'll try it. Thx.