Airlocked Fresh Water System? Help!

labatt · #1 (**permalink**) 05-16-2008

So we're launched, and I was working on draining the antifreeze from our system. Connection wise, we go from two tanks (port and starboard) to a mixer valve, to a mystery cylinder that I can bleed water (or air) out of (small twist valve on top), to a 12v pump, to the distribution to sinks. I turned on the power to the pump and it primed for a few seconds. I turned on the galley sink, and water only came out in a trickle. I turned on the sink in one of the heads, and the water came flying out under pressure. I let it run for about 90 seconds and it turned to a trickle. Now, with water in the tanks, all we get are trickles out of the sinks, but the pump still primes every minute or so (vs. every 30 seconds normally). Just for the heck of it, after we had the problem, we opened up the mystery cylinder twist valve and a ton of air came out. Now when we open it up, we get water. It's way to small to be an expansion tank - it's about 12 inches high by 4 inches round and looks like a filter system, but I can't seem to figure out any way to get to a filter, so I'm assuming it's not.

Anyway, it kind of looks like an airlocked system, but I'm not sure how to fix it. Do people concur? Any other ideas? If it's an airlock, any suggestions on how to fix it? There are a lot of hoses, so I would prefer not to disassemble the entire system.

erps · #2 (**permalink**) 05-16-2008

Seems like if the mystery cylinder was on the suction side of the pump, you wouldn't be able to bleed air out of it. Can you bypass it to troubleshoot your system further?

camaraderie · #3 (**permalink**) 05-16-2008

The tank may be a small accumulator tank and by letting the air out of it you have defeated the purpose. Drain the water...close any valves and try again.
You may need to prime the system by filling the feed hose to the pump with water and elevating it above the pump. Turn OFF the water input to your hot water heater to eliminate that as an issue. Start with all faucets off and open only the closest one to the pump first until a nice steady flow with no air is present. Then close that and move to the next faucet etc. etc.
Do this ONLY with the cold water side. Then move to the how water side and repeat with the valve to the hot water heater open.

Of course it is possible that you are sucking air on your intake side but try the easy stuff first.
Good luck!

labatt · #4 (**permalink**) 05-16-2008

The problem existed prior to opening the valve on the small cylinder tank (which would hold 2 cups of water MAX, so I'm pretty sure it's not an accumulator tank). I opened the valve to see if I could fix the problem.

Sailormann · #5 (**permalink**) 05-16-2008

Quote:

The problem existed prior to opening the valve on the small cylinder tank (which would hold 2 cups of water MAX, so I'm pretty sure it's not an accumulator tank). I opened the valve to see if I could fix the problem.

No need to waste time making excuses. Be off and do as Camaraderie told you to and then report back

Mainepep · #6 (**permalink**) 05-16-2008

Your pump runs to accumulate pressure into the small tank so that your system stays pressurized without the pump running all the time. You will have to bleed the system to get the water out of the small tank.

Good Luck

Mainepep

WinterRiver · #7 (**permalink**) 05-16-2008

Oh, fine, go ahead and add something to my list

. One of the goals for this week is to trace all my hoses and sort out the water system. I guess I'll find the accumulator tank. I'm sure there's one here somewhere.... Hoping, but not trusting, that the PO didn't do anything too odd.

Here's a clear explanation of accumulator tanks: This Old Boat - Google Book Search

tommyt · #8 (**permalink**) 05-17-2008

Sounds more like filters to me. That mystery tank could just be one. Trace back and see clean all filters. Water tanks and lines are most vulnerable to issues as you begin the year. After draining in the winter, filters are usually the culprit...especially if the system is not really clean to begin with.

OH, those filters most likely are at the pump on the feed side. You could also be having a problem with the filters on your faucets. Amazing what those little buggers collect. When you clean those filters you don't want your wife to see what comes out. Don't drink the water!

Also, to the person worried about your accumulator tank, most boats I have worked on have a water tank and a pump, no accumulator in between. If you don't find one in any obvious places...stop looking!

camaraderie · #9 (**permalink**) 05-17-2008

otaga...you are right...I did not catch that it was between the tank and the pump rather than between the pump and everything else. The only thing that makes sense there is a filter as Tommy said. Wierd.

timebandit · #10 (**permalink**) 05-17-2008

Might wanna open you deck cap to insure you are venting. It is an easy and quick test.