Anti Syphon and the Solenoid Value

[foggysail]

GEEZ, I am also an engineer but in the electrical field. I have a 40' boat that I have spent the last couple of very hot days ripping out a floor in one of our bathrooms--heads for those who prefer, modifying a PVC Schedule 40 waste line, adding 1/2" pex tubing for fresh water to my new Raritan Elegance toilet. I will say with clarity, there just aint nohow room on my 40' with a 14' beam to add another water tank">fresh water tank dedicated to the head. If you have not been there, done that it is easy to advise just add pipes, wires storage tanks safety valves double up on backflow preventers....

Years ago on my very first design engineering assignment while I worked for a very large defense contractor, I started down the specification route. A senior engineer was kind to give me some advice. "Heeey, why are you building a brick shithouse??? Keep it simple, don't bury this project with unneeded costs!!" Great advice then, great advice now!!!

Foggy

[HopCar]

Sdowney you're right about it being rotted organic material that causes odors in salt water flushed toilets. There is a passage way around the rim of the bowl that delivers water to all those little holes in the rim. It's this passage way that collects the organic material that rots. The smell gets into the air through the holes in the bowl rim. I have a Groco sea strainer in my intake line. It catches the big stuff and I don't have an odor problem. There used to be a device that you installed into the intake line that would release clorine into the intake water each time you flushed. You had to replace the chemical cake in it every once in a while. I once broke up one of those cakes you drop in home toilet tanks and put chunks of it in my toilet sea strainer. It wasn't worth the effort.

As for fresh water flushing, just buy a marine toilet that was designed for that. That way when you get sick you've got somebody to blame besides your self.

Foggy, if you purchased the Raritan Elegance that was designed to flush with pressurized fresh water, it came with all the do dads to keep the critters from swimming up stream to your drinking water. No need for a dedicated tank.

[sdowney717]

Originally Posted by HopCar

I have a Groco sea strainer in my intake line. It catches the big stuff and I don't have an odor problem

Interesting, I had thought that would help with odors. It is something I will think about adding to my system. I have a seacock feeds sea water to head. And I suppose the filter could be in the bilge rather than near the head.
How often would it need to be cleaned out or does it?
Do these come with various sized mesh for filtering?
I currently have a strainer on the generator input line, it would be a long run to share that source. Or I could just remove the gen's strainer to try it on the head.


The thru hulls for gen and head have a bronze cover with holes on the outside of the hull which covers the seacock. So really the gen does not need that strainer. I could just use it on the head.

looking I found this which might just work
http://www.ebay.com/itm/RV-MARINE-WA...#ht_500wt_1272

[HopCar]

Sdowney, I don't have to clean mine very often because I went with a real bronze 3/4" sea strainer. That's really overkill. The one you found on Ebay would work but I think it might need to be cleaned too often as it is small with a very small mesh strainer. If I was doing mine again I think I'd use one of these: Shurflo 1" Raw Water Strainer - 253320-01

[jeremiason]

Originally Posted by sailorchic34

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.

I have the same toilets on my boat...

Our solenoid valves are installed about three feet higher than the toilet bowl (Above the boats water line)....

So even if the solenoid valve failed and remained open and there was no water pressure, gravity would cause the water on the down hill side to flow into the toilet, not the other way around since it is an open contection at the toilet.

Also it is very unlikely to get a suction in the fresh water system since most fresh water pumps have one way valves.

IMHO I think a anti-suction valve is redundant.

[sailorchic34]

If your feeding the rim of the bowl from the solenoid valve, its mostly safe (not 100% more like 90%, but mostly). If your feeding the fresh water to a fresh water pump connection at an electric head. Its not safe at all. The issue is bacteria contamination.

While it might work for years fine and dandy, there is a high likelihood that the line from the solenoid valve to the head will get contaminated. Over time the surfaces of the solenoid valve seat will also get contaminated. Have a little wire drawing of the seat or a worn valve guide and I could easily see contamination spreading upstream of the solenoid valve.

Some electric heads have the water pump and the waste ejector on the same motor with a simple seal between the two pump chambers. To a bacteria its pretty much wide open.

The typical atmospheric vacuum breaker provided with many electric heads, offers an open air break in its design. Its a simple solution that pretty much eliminates cross contamination issues.

Hey I'm just this chick who's designed plumbing and piping systems for over 30 years so what do I know.. In any case, always follow manufacturers instructions....

[sailorchic34]

Its not about water flow and higher to lower pressure zones, etc. Its Bacteria which can swim upstream regardless of line pressure or height of line above the head. A higher line pressure helps, sure, but its still not safe, not at all really...

[gbanker]

well, if this thread is still going I want to slide in with a question of a similar nature. I have electric fresh water heads that have the fresh water supply above the heads. The heads slowly filled with water so solenoids were installed after the (independent) pumps and before the heads. These solenoids are constantly failing - getting anywhere from days to several months use before having to replace them (Jabsco heads and solenoids).
So, would plumbing so that the solenoid are before the pumps solve this issue or ?. Also, do I need to do anything differently to prevent blacklist contamination?

[sailorchic34]

Me, I would think the solenoid valve would be installed before the pump on the head, But check the manufacturers installation instructions. As to the coil burning out, are you sure your using the right voltage. Is your boat 12V or 24V and does the coil specification match the voltage.

[jeremiason]

We two Jabsco Quiet Flush fresh water models on our boat. We have the same issue and were purchasing new valves about every six months. Then I took one apart.

They get particles in the rubber gasket. I unscrew the solenoid and clean the rubber gasket. Put it back together and it should work fine.

Installing a carbon filter in your house water system will also help with crud getting in the valve.

[gbanker]

Tom,
My failure mode is that the valve stops opening. Then, because the solenoid is is the supply line after the pump, the water pressure causes the hose to burst or spray water from the loosest fitting.
Are your failures a failing to open?
Thanks

[gbanker]

And sailorchick34, the solenoids are not burning out - at least when I remove the problem solenoid and connect it to power I can hear it clicking.

[bstreep]

We have 2 Quiet Flush heads. We also had the same problem with occasional head overflowing. We noticed that it happens most when the water tanks are low. So, it might be a pressure problem. That being said, we've had only 1 problem since installing a filtration system about a year ago.

[gbanker]

thanks Bill. I plan to 're- plumb with the solenoid so it is in line before the pump that pressurizes
the water to the head. Hate to replace the head with a different brand without knowing the problem.