Where to position vented loop, exhaust or intake side

[chowdan]

Trying to determine where the "proper" location of a vented loop should be, or if position doesnt matter.

My current setup has the vented loop between the water pump">raw water pump and the heat exchanger, however, the diagrams I am seeing online indicate that the vented loop should be located after the heat exchanger, before injecting into the mixing elbow.

Whats the proper position?

[Reefmagnet]

I'd go between heat exchanger and mixing elbow because it means less water can drain into the waterlock with engine off.

[Dsanduril]

The closer the vented loop is to the exhaust/mixing elbow the less water there will be that falls down into the mixing elbow when the vent breaks a siphon. This, in turn, means there's less water that has a chance to make its way back up the exhaust system while the engine is off and potentially cause a lot of grief. If you have a fair sized water muffler or similar in the exhaust then the the volume difference is probably pretty negligible in comparison.

Bottom line, preferred is after the HX (for the reasons stated) but before the HX can work just fine. On some engines the connection from HX to elbow is so tight/special that trying to insert a vented loop there is somewhere between an exercise in frustration and impossible.

[chowdan]

Thanks guys. I just put an order in for a new piece to run from the RW to heat exchanger(Yanmar OEM part). Another $40 is a drop in the bucket when it comes to all new hoses.

I'll go with adding the vented loop between heat exchanger and mixing elbow. Reducing the amount of water that can enter the muffler is ideal as I've got a fairly long run - about 7.5 feet from lift can to loop before exiting so having the least amount of water in this area is ideal.

[DeValency]

Originally Posted by chowdan

Trying to determine where the "proper" location of a vented loop should be, or if position doesnt matter.

My current setup has the vented loop between the raw water pump and the heat exchanger, however, the diagrams I am seeing online indicate that the vented loop should be located after the heat exchanger, before injecting into the mixing elbow.

Whats the proper position?

The later is the correct way to go. You don't want sea water reversing into the elbow and heat exchanger

[GordMay]

I realize the issue has been resolved, but FWIW.
See ➥ https://www.cruisersforum.com/galler...r&imageuser=79
And ➥ https://www.cruisersforum.com/galler...r&imageuser=79

[sailing_gal]

And, make sure the vented loop is above the waterline, even when heeled.

[DeValency]

The drawings here show the loop but not the vent. A loop only will not prevent a back flow at some heeling conditions! A vent must be installed.

I don’t like the loops with a valve, these tend to clog. The better solution is a small heat resistant tube (copper, silicone...), that can go even higher and discharge into the cockpit drain (that’s the original at my center cockpit) or outside.