Siphon Cap 101

[Mike Smith]

I was on Breezer today doing some work and trying to find the origin of a leak in the head area.  There has been an accumulation of water in the shower after a few rainy days.  I opened the appropriate thru hull and turned on the sump pump to drain the water out.  The pump ran OK but the water went nowhere - there was no suction.  I checked the strainer but it was clean, so I started the pump again and began following the hose over to the pump, checking connections and then up and over to the antisiphon valve.  I remember some advice about checking the valve every so often to make sure it is not obstructed, so I started unscrewing the cap.  As soon as I did, all the water in the shower sump was sucked down the drain.  Great - but I also noticed some air escaping and some water dribbling out from under the anti-siphon cap.  So, my question is, how tightly do you screw the antisiphon cap down? Half-way? All the way?  Is it safe to have it unscrewed while you are away from the boat?  I always close all thru hulls while Breezer is at the dock.  I know this is pretty elementary, but I'd like some advice rather than unexpected water in the boat!

Mike

[Ron Hill]

Mike : To answer your question - any anti siphon valve should be turned down finger tight.

You shouldn't get water accumulating in the shower sump after a rain.  You've got a leak somewhere in the head area.  
Look at the rubber check valve inside the anti siphon.  If you squeeze it slightly the flat sides of the valve should open easily.  Make sure that there's no junk blocking that opening.  When reinstalling make sure that the "points" of the rubber valve are down and turn the retaining nut finger tight.  You might want to spray the rubber valve with silicone to keep it limber, but wipe off any excess silicone.  Think I called Forspar at (741)858-8820 and got some extra rubber valves.  
Hope this is of some help.  

[Mike Smith]

Thanks, Ron -

The anti-siphon valve I'm talking about is located in the cabinet underneath the sink in the head.  It is made of rubber/plastic and screws onto a threaded nipple at the apex of a bronze or plastic inverted U-shaped pipe which is mounted high up on the bulkhead above the waterline. The output hose from the sump pump attaches to one end of the pipe and the hose to the thru hull attaches to the other end.  The valve itself is tiny - is it actually a check valve?  I'll check it out for crud as you advise.

What I can't figure out is why the standing water in the shower sump was sucked out the instant I loosened the valve.  It may have something to do with the way the hoses are connected in there.

Mike

[Ron Hill]

Mike : I know exactly where THEY are located.  Infact there are two of them under the head sink.  Yes, it a VERY important check valve - to break the column of water so it will not flow/siphon "back wards".

One is for the anti-siphon of the raw water into the exhaust riser just above the hump hose into the muffler.  
The other is for the shower so sea water will not flow back up (siphon) into the shower drain when the thru hull is open.

If you look at page 4.4.10 (Engine Exhaust System ) of your Owners Manual you'll find a diagram of that anti-siphon valve in "illustration B".
Call Forspar for replacements.  

[DEMERY]

Ron,

I think the check valve that Mike is talking about is to prevent the water between the vented loop and the drain from running back into the shower when the shower sump pump is turned off. The series of connections are: shower drain, check valve, pump, vented loop, thru hull. I recall in the past members have discussed that hair, soap scum, etc. can cause the valve to allow drain water to seep back into the shower. I would recommend taking the check valve apart for a complete cleaning.

Regards,

Dave C34 - 1990 / 982

[DEMERY]

Ron / Mike

Upon further review, Mike is talking about the vented loop. I still think that soap scum, hair, etc maybe the culprits.

Regards,

Dave

[Mike Smith]

I removed the cap and valve and blew down from the top.  The check valve didn't open but it flew out of the cap!  It must have been stuck shut. I found it across the galley, squeezed it open, washed it out, and then hit it with silicone spray and re-installed it.  Now, where is that owner's manual...

Finally getting power back to my dock.  Electrician is coming tomorrow to replace everything, so maybe the day after I'll have it turned back on and can charge the batteries.

The road out to the barrier island was opened this week, so we drove out to check things out yesterday.  Absolute destruction.  It has been four months since Ivan struck and it will be years until things are back to normal down here.

Mike