Anti-siphon loop for engine

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john williams

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Hi,
I need to install an anti-siphon loop on the heat exchanger outlet and the exhaust of my beta marine 16
Having looked into it the system could either be a loop with a valve or a loop with a small bore outlet at the apex to a run over board.
I am just staggered how much either of these loops are going to cost - i.e. about 80-100 notes for what is - in the latter arrangement - basically a t- piece .
My question is - can you just use a made up T piece and save considerably or am I missing something - which has happened before .........
Thanks
 
john williams said:
Hi,
I need to install an anti-siphon loop on the heat exchanger outlet and the exhaust of my beta marine 16
Having looked into it the system could either be a loop with a valve or a loop with a small bore outlet at the apex to a run over board.
I am just staggered how much either of these loops are going to cost - i.e. about 80-100 notes for what is - in the latter arrangement - basically a t- piece .
My question is - can you just use a made up T piece and save considerably or am I missing something - which has happened before .........
Thanks
Click to expand...

You could do home brew, but then you wouldnt have "Vetus" stamped on it. Who would want to go on your boat then huh?
last exhaust system I worked with had an inverted U bend with welded on tee for the heat exchanger outlet and just a loop of exhaust hose up to deck level for the exhaust, no tee or hole.
 
john williams said:
Hi,
I need to install an anti-siphon loop on the heat exchanger outlet and the exhaust of my beta marine 16
Having looked into it the system could either be a loop with a valve or a loop with a small bore outlet at the apex to a run over board.
I am just staggered how much either of these loops are going to cost - i.e. about 80-100 notes for what is - in the latter arrangement - basically a t- piece .
My question is - can you just use a made up T piece and save considerably or am I missing something - which has happened before .........
Thanks
Click to expand...

When i installed my Nanni i devised a AS vent it loops up under the main hatch / bridge deck & fitted between the raw water pump & the HE, this "piddles" into the cockpit , so i can see what going on & is an early tell tale of a blockage.
it matters not where in the system the vent is
 
Last edited:
john williams said:
Hi,
I need to install an anti-siphon loop on the heat exchanger outlet and the exhaust of my beta marine 16
Having looked into it the system could either be a loop with a valve or a loop with a small bore outlet at the apex to a run over board.
I am just staggered how much either of these loops are going to cost - i.e. about 80-100 notes for what is - in the latter arrangement - basically a t- piece .
My question is - can you just use a made up T piece and save considerably or am I missing something - which has happened before .........
Thanks
Click to expand...

It needs to be a raised loop with the vent at the highest point, not just a T piece in the existing pipework with a raised vent hose.

No reason not to make up a suitable fitting and easy if you opt for the type that just "pees" overboard or into a cockpit drain.

With the peeing type you know if it's peeing that it is not blocked etc. The valved type need regular maintenance and often dribble into the bargain
 
sailorman said:
When i installed my Nanni i devised a AS vent it loops up under the main hatch / bridge deck & fitted between the raw water pump & the HE, this "piddles" into the cockpit , so i can see what going on & is an early tell tale of a blockage.
it matters not where in the system the vent is
Click to expand...

So long as its not on the suction side of the pump!
 
Dougal Tolan said:
You could do home brew, but then you wouldnt have "Vetus" stamped on it. Who would want to go on your boat then huh?
last exhaust system I worked with had an inverted U bend with welded on tee for the heat exchanger outlet and just a loop of exhaust hose up to deck level for the exhaust, no tee or hole.
Click to expand...

But that has no point at which air is admitted to break the syphon
 
Dougal Tolan said:
You could do home brew, .....
Click to expand...

Thats not a bad idea. On my own boat I have a cast 'Parsons Box' (it looks bell shaped but has an internal division) which has BSP nipples to attach the exhaust hose from the engine, cooling water hose from the engine and mixed exhaust/water outlet hose. It would not take that much ingenuity to purchase what is commonly called 'malleable pipe fittings' and make up a simple system and very low cost. Appropriate thread sealing products would have to be used.
 
BlowingOldBoots said:
Thats not a bad idea. On my own boat I have a cast 'Parsons Box' (it looks bell shaped but has an internal division) which has BSP nipples to attach the exhaust hose from the engine, cooling water hose from the engine and mixed exhaust/water outlet hose. It would not take that much ingenuity to purchase what is commonly called 'malleable pipe fittings' and make up a simple system and very low cost. Appropriate thread sealing products would have to be used.
Click to expand...

My method is flexible hose & a home made brass fitting so no rusty marks from the exhaust & clean water into the cockipt
 
sailorman said:
When i installed my Nanni i devised a AS vent it loops up under the main hatch / bridge deck & fitted between the raw water pump & the HE, this "piddles" into the cockpit , so i can see what going on & is an early tell tale of a blockage.
it matters not where in the system the vent is
Click to expand...

That's similar to how mine is done. I have a stainless tee in the pipe from the pump to the HE, with the small pee pipe fitted just outboard of the gunwhale so it pees overboard, but it's still visible.
 
john williams said:
Hi,
I need to install an anti-siphon loop on the heat exchanger outlet and the exhaust of my beta marine 16
Having looked into it the system could either be a loop with a valve or a loop with a small bore outlet at the apex to a run over board.
I am just staggered how much either of these loops are going to cost - i.e. about 80-100 notes for what is - in the latter arrangement - basically a t- piece .
My question is - can you just use a made up T piece and save considerably or am I missing something - which has happened before .........
Thanks
Click to expand...

This is my anti-siphon loop on my engine with the small pipe going to a connection just under the deck toe rail.

IMGP2717_zpsblk3e0gn.jpg


I have also made these from BSP threaded pipe fittings that require no welding just screwing together

I have also used plastic fittings like these to make up swan loops with or without vent fittings.

IMGP2982_zpsudvzrnsa.jpg
 
The Vetus prices are silly money. ASAP do a range with optional check valve, £21 for a 3/4 inch loop to suit the OP's B16, plus the price of hose tails. The check valve adds ~£10 if required. I bought one but then removed the ball to make it a piddler.
Saves building one up DIY.
 
Mine is simply a soldered up T piece located at the top of a clear plastic loop of 19mm pipe. It piddles into a cockpit drain. Visual and also makes a nice gurgling sound on engine shut down, confirming it's not blocked and has allowed air into the siphon break. Would never want to have a valve with its attendant maintenance and possible blocking. And all for very little money. Vetus - no way !
 
Forgive my ignorance, such modern technology has overtaken my old Kubota donk.
But what is an anti-syphon loop, where does it fit and what do I need to know about what it does, or doesn't?

I only ask as the supplier and installer of a potentially new Beta (or Nanni) for Khamsin has suggested I might need one - along with a boatful of other extras.
 
Robert Wilson said:
Forgive my ignorance, such modern technology has overtaken my old Kubota donk.
But what is an anti-syphon loop, where does it fit and what do I need to know about what it does, or doesn't?

I only ask as the supplier and installer of a potentially new Beta (or Nanni) for Khamsin has suggested I might need one - along with a boatful of other extras.
Click to expand...


Engines_and_around_180px_hoog_2.jpg


http://www.vetus.com/engines-and-around-the-engine/cooling-water-system.html

http://www.vetus.com/videos/all/engines-and-around-the-engine.html 8 mins into the video
 
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It fits anywhere downstream of the seawater pump, usually in the hose from the heat exchanger to the injection point in the exhaust (if there is one). Otherwise in the run from the seawater pump to the engine. Taken well above the waterline, its purpose is to vent the waterpipe when the engine stops to prevent syphoning back. Good explanation in the Vetus catalogue or on their website.
 
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