Optimum height for A/S loop?

[colind3782]

What's the optimum height for the anti-syphon loop on the heads outlet. Above the waterline obviously but not so high that the pump can't handle it?

It's straight out with no holding tank.

 

[MoodySabre]

Above the waterline when heeled.

 

[pvb]

What's the optimum height for the anti-syphon loop on the heads outlet. Above the waterline obviously but not so high that the pump can't handle it?

The pump will handle it easily. Where the toilet is always above the heeled waterline, Jabsco specify at least 30cm of pipe above the natural waterline. Where the toilet is below the waterline, Jabsco specify at least 20cm of pipe above the heeled waterline. In practice, it's difficult to determine the heeled waterline with accuracy, so I'd err on the side of caution! There are good diagrams in the Jabsco toilet manual.

 

[colind3782]

The pump will handle it easily. Where the toilet is always above the heeled waterline, Jabsco specify at least 30cm of pipe above the natural waterline. Where the toilet is below the waterline, Jabsco specify at least 20cm of pipe above the heeled waterline. In practice, it's difficult to determine the heeled waterline with accuracy, so I'd err on the side of caution! There are good diagrams in the Jabsco toilet manual.

Thanks for that. It's a Matromarine toilet and the waterline is just below the toilet rim. I'll have a look at the Jabsco manual before I fit the loop.

 

[johnalison]

The more inboard the loop, the less height needed. My inlet loop is only about a foot above the bowl but is near the centreline. My holding tank functions as my outlet loop but on our Sadler it went up to the deck level and the pump coped alright.

 

[LittleSister]

The more inboard the loop, the less height needed.

Thanks for pointing that out. I 'knew' that, had I considered it, but somehow I'd failed to do so when trying to solve my intended heads re-plumb conundrum.

 

[Daydream believer]

It might be worth considering the amount of fluid trapped on the "up" side of the pipe because you will not be able to clear it & if the pump valve leaks a bit it MAY run back into the bowl. If it is also stored in the pipe which is not a good sanitary hose it MAY lead to additional smell & it MAY lead to a long length of pipe build up of calcium if left to long to stagnate in the pipe. A smaller loop will hold less fluid- possibly

 

[pvb]

It might be worth considering the amount of fluid trapped on the "up" side of the pipe because you will not be able to clear it & if the pump valve leaks a bit it MAY run back into the bowl. If it is also stored in the pipe which is not a good sanitary hose it MAY lead to additional smell & it MAY lead to a long length of pipe build up of calcium if left to long to stagnate in the pipe. A smaller loop will hold less fluid- possibly

As the toilet pumps straight out to sea, rather than to a holding tank, there's no reason not to pump sufficiently to ensure that the pipe is only left with seawater in it.

 

[johnalison]

As the toilet pumps straight out to sea, rather than to a holding tank, there's no reason not to pump sufficiently to ensure that the pipe is only left with seawater in it.

That is true, but I would imagine that a certain amount of mixing takes place in the pipe, so that under normal conditions the water column will always be contaminated to some extent.

 

[Poignard]

The top of my loop is as high as it can be, just below the underside of the side deck.

 

[colind3782]

Thanks for all the tips so far! Keep 'em coming