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Old 10-06-2012, 01:22   #1
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Anti Syphon and the Solenoid Value

I have an electric jabsco 37010 head plumbed to the sink outlet for a fresh water flush.
The issue I have is that the pump won't prime due to the anti syphon valve which is between the sink outlet and the pump inlet. I have read in this forum that the anti syphon valve should be between the pump and the toilet bowel, this is very logical and some jabsco manuals state this. Other jabsco manuals say different and say to use a solenoid valve to close the anti syphon on priming, or flushing.These valves are $160 for a basic one and $250 for a flash one, I can't see why I need to ever use a solenoid when the easy solution is to place the anti syphon is on the exit of the pump.
Any suggestions?
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Old 11-06-2012, 22:06   #2
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Re: Anti Syphon and the Solenoid Value

If your connected the water supply to the sink drain below the bowl, as per peggy's recommendation, then an anti-siphon valve is not needed at all. I'm assuming thats what your doing.

If your connected to the pressure water system, then you will want a solenoid valve before the anti siphon valve. With a hard connection to a water line, the anti siphon always goes before the pump... There is a real danger of cross contamination in the electric pumps on marine heads. So In my mind, the anti-syphon / backflow preventer always goes before the pump...

The only exception is using peggys method of connecting off the sink drain. its an elegant solution to a problem too.
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Old 12-06-2012, 01:54   #3
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Thanks sailorchic34, correct, no anti syphon valve needed, yet there is the chance I would want to preserve fresh water and open the seacock for salt water flush, thus I do need to put either the anti syphon back in this instance. I received a private response that said that not all heads have a hose between the pump and the bowl, thus these ones need an anti syphon with solenoid value. Which more or less answers the question of why a solenoid is ever needed if the anti syphon is between the bowl and the pump. I did also read that the expensive solenoid prevents cross contamination of the fresh water, mmmm can you ever be sure though? Sink drain flush for me everytime.
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Old 12-06-2012, 09:03   #4
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Re: Anti Syphon and the Solenoid Value

Markhunter, If the toilet is ever below the waterline, heeled or up right, an anti-siphon loop between the pump and bowl might be a good idea if you choose to flush with salt water. Siphoning is not a big danger with that toilet as the inlet pump is a rubber impeller type pump. Each of the blades on the impeller act as a check valve to prevent water flowing into the bowl. Of course if the blades are damaged, water could flow into the bowl.
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Old 12-06-2012, 19:54   #5
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Re: Anti Syphon and the Solenoid Value

well I may have had a blonde moment. So is the anti siphon the typical u-bend or a plumbing air-gap thing. They sort of do the same think but for two different reasons. Normally on domestic fresh water flush you would have a backflow preventer, some times called an anti-syphon valve between the fresh water and the head pump. It protects the fresh water from an cross contamination. from the head.

That is what I was thinking about from your first post. If your talking about the typical U-bend anti siphon, thats another animal.

Agree with hopcar that if the rim of the bowl, is below the waterline on any heal, then you want an anti-syphon installed between the bowl connection and pump. You can't really pull from an anti siphon, only push through. If its working right anyway. If the rim is above the water line at all times then you don't need an anti siphon on the inlet for salt water.

if connected to a pressurized fresh water system, THEN the solenoid valve and backflow preventer is needed.

Home toilets have the backflow preventer built in to the tank or flush valve design. Marine heads as a rule don't, just fyi
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Old 12-06-2012, 22:29   #6
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Re: Anti Syphon and the Solenoid Value

I think we need a better name for the trick of plumbing the toilet inlet to the sink drain.
How about the PH Connection? No that won't work, Raritan makes a PH toilet. You don't think that's named after Peggie do you? I guess we could call it the Peggie Hall Memorial Toilet Connection! That should flush her out if she's lurking. (Pun Intended)
So she won't get mad at me, I'll plug her book.
Buy This: Get Rid of Boat Odors by Peggie Hall
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Old 12-06-2012, 22:30   #7
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Re: Anti Syphon and the Solenoid Value

I wouldn't plumb a freshwater boat supply to an electric head without a solenoid valve. But that's just me.

As for "home toilets", they use a whole different concept, with flush tanks that are filled via a hose and a mechanical valve cutoff. No chance for contamination.

And (sorry), it's "you're" not "your".
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Old 13-06-2012, 00:07   #8
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Re: Anti Syphon and the Solenoid Value

Wow thanks, Its a darn good thing I'm NOT just a bimbo, but a engineer too and not an English major isn't it.

BTW, Peg Hall who is the goddess of all things related to marine heads had a real nifty way of connecting fresh water via the sink drain, which is what the OP was writing about. Being a blonde bimbo I sometimes discuss an issue from several directions. Being an engineer I sometime provide too much information.

Darn it now I have the grammar police after me....

BTW, the hose in the tank just fills the bowl and not the tank itself, the ball cock assembly which includes that mechanical float assembly, fills the tank and also is designed to preclude backflow. Of course there are other ways its done in residential and commercial plumbing fixture design. But I'm blonde, so can't possibly know anything about that either.

NO I'm NOT PMSing either...... well OK maybe a little... GRIN...

Hope YOU'RE happy now....

Hopcar: How about just calling it the Peggy Connection, or is that just a little too PC...
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Old 13-06-2012, 00:25   #9
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Re: Anti Syphon and the Solenoid Value

Quote:
Originally Posted by sailorchic34 View Post
Wow thanks, Its a darn good thing I'm NOT just a bimbo, but a engineer too and not an English major isn't it.

BTW, Peg Hall who is the goddess of all things related to marine heads had a real nifty way of connecting fresh water via the sink drain, which is what the OP was writing about. Being a blonde bimbo I sometimes discuss an issue from several directions. Being an engineer I sometime provide too much information.

Darn it now I have the grammar police after me....

Like I said, "sorry".

As an Engineer, 1) you're (or "your") a college graduate and should have had to suffer through a year of college english, and 2) most of the Engineers I know (brother and father both) are very exacting in their ("there" or "they're") use of the language. Writing "your" instead of "you're" detracts from your credibility as a writer - and you appear to be a pretty decent one. Please don't take offense.

For instance, I've found there is no good way to point out to someone that their fly is open.

And yes, I'm 1) very aware of and respectful of Peg's pedigree and 2) aware of her way of plumbing to the sink - which I guess works for some, but one effectively loses (or "looses") the use of the sink.

Again, my apologies if I offended you.
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Old 13-06-2012, 07:34   #10
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Re: Anti Syphon and the Solenoid Value

Sailorchick, The Peggy Connection works for me except for one thing. I wouldn't bring it up, especially now, except that the Head Goddess jumped on me about it. Her name is spelled Peggie.
Please don't kill me.
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Old 13-06-2012, 07:41   #11
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Re: Anti Syphon and the Solenoid Value

Sailorchick, I know you know a lot about pumps. What do you think of my theory that water is unlikely to be able to free flow through a rubber impeller type pump, such as the one on the OP's toilet?
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Old 13-06-2012, 09:59   #12
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Re: Anti Syphon and the Solenoid Value

Hopcar: HAHAHAHA, No problem hopcar, and apologies to Peggie You quite correct in that the rubber impeller pumps are a type of positive displacement pump and as such will not generally free flow.

bstreep: Actually I've never had even a minute of college. I have however sat and passed the professional engineer exam the first time I took it many years ago. All that engineering background is based on lots of years of reading every mechanical engineering book and material datasheet I could find and applied application of same.

Short answer is I know piping, from plumbing, to fire protection, hydronics, process, steam and cryogenics. Plus all the fiddily bits, like pumps, chillers, boiler, etc, how it all goes together and the various failure modes for same.

I've also messed with digital electronics, computers since the kim-1, Taught myself C and C++, along with Fortran and some assembler, just for fun. I also cook and sew....

Alas english and writing have never my strong suit. Thank god for spell checkers... Pretty much went down hill from 3rd grade on.. Apologies, I'm sometimes a little Bitc...Er... grumpy sometimes. I'm much better now thank you very much....
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Old 20-06-2012, 08:32   #13
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Re: Anti Syphon and the Solenoid Value

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Originally Posted by sailorchic34 View Post
If the rim is above the water line at all times then you don't need an anti siphon on the inlet for salt water.

if connected to a pressurized fresh water system, THEN the solenoid valve and backflow preventer is needed.
Personally, I am happy with just a solenoid even though I did install a backflow protection valve because it came with the toilet when I purchased it new.

Yes, I understand that plumbing codes require a backflow prtector on things that could backflow into the main such as a hot water storage tank or even a urinal. But my understanding is there are no laws for boats other than the no discharge crap (literally speaking).

And of course, no sane person would want to think his drinking water just arrived from his toilet. A fresh water toilet (head of course) would empty a pressurized storage tank if it lacked a flow solenoid. Here a backflow protector is over kill.
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Old 22-06-2012, 18:56   #14
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Re: Anti Syphon and the Solenoid Value

You are quite correct that there is no laws requiring backflow devices on potable water connections to heads on boats. The intent of the plumbing codes for landside buildings is protecting the health of the population. Just because there is no law, does not mean some espects of the code is not important to marine systems.

Yes you do need a solenoid valve on the pressure water system to a head. You also should use a Backflow preventer of some sort too. This will protect water supplies from bacteria that can swim upstream. A solenoid valve will not protect the fresh water from cross contamination. It is not a foolproof means by far.

To me boats are a large biohazard anyway. The water stored on the boat for more then a few days has lost all the free chlorine in the water. So a small bit of cross contamination could easily grow and multiply.

As an engineer who understands the dangers involved, you really NEVER want to connect a potable water source to a marine head without some form of approved backflow prevention. A solenoid valve will not prevent cross contamination.
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Old 22-06-2012, 19:07   #15
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Re: Anti Syphon and the Solenoid Value

I dont think I would even trust a backflow prevention device. It might depend partially on maintaining a positive line pressure.
I would think a separate fresh water flush tank is ideal solution if you got the space. If it gets a lot of use then it will run out of water. Unless you just use it for a final flush before leaving the boat. Problem of odor is the marine life dies and rots in the system. Too bad you cant sterilize the line with something, how about a filter to catch the bigger life forms. Do an occasional backflush to clear it out. Just thinking a little.
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