Which vented loop?

I need to install new vented loops on the Lehman exhausts. Someone has recommended the Vetus models, which are some sort of composite or high-end plastic. Groco also makes a very substantial bronze model. Does anyone have experience with either of these . . . or other recommendations?

Second question: do most of you route the air bleed lines overboard or back to the water lift muffler, as they are on my boat?

I bought the Vetus as it doesnt need to be complex or robust.

I bought the Vetus model with the overboard discharge line, no vacuum breaker valve as they are known to stick shut with hot salt water deposits.

The Vetus was also smaller in size so that was nice.

I have mixed feelings on the through hull discharge. The water flow near a door is nice to check, but the water stain down the hull is annoying. I have to fashion a drip lip to hopefully lessen that.

There are two types of vented loops. One has a simple high point vent which is usually routed overboard because you have flow any time the engine is running. The other has a check valve that lets air in to break a vacuum but keeps normal flow inside. Yes, the second type can fail, but they mostly fail open which is mostly safe but messy.

A reasonable approach is to use the check valve type but hook up a hose to the valve that is routed to the bilge. Check that hose periodically for flow and if you see it, then clean the check valve.

David

But they can fail closed, allowing a major issue with backsiphoning to the engine.... so why chance it?

All the reading I have done recommends no valve for that reason, simple risk managenment.

Anything wrong with routing the vent line back to the water lift muffler, as several Defevers seem to do? The muffler obviously vents to atmosphere and any water that gets in would be expelled with the rest of the water/exhaust mixture.

As long as when the engine shuts down, the tube will be vented to the atmosphere and not suck back water.

Pardon my ignorance here, both boats I have owned with Lehmans did not have these, I thought that was the purpose of the water lift muffler? Where in the exhaust are they installed?

Just prior to water injection elbow in exhaust.

Simplified version....

They are only needed if part of the raw water system is lower than or close to the waterline. To the point where if you shut down under the right circumstances, the system could siphon water into the exhaust system and fill the engine.

I decided to go with the Vetus vented loops. Each loop, as before, vents to the respective muffler. The blue line is the injection source for the stuffing box. People seem to like the Vetus loops, but they seem grossly over-priced for a piece of plastic . . . oh, wait; it's a boat . . .

Ian, Don't worry about the cost (love spending other peeps money!), it complements an already pretty engine room. D44 have a really nice engine room!

Angus99 has a beautiful engineroom setup. Clean and orderly prepurchase. I'm sure its even nicer now.

Shouldn't you double clamp your hoses?

L.

Sailor of Fortune said:

Ian, Don't worry about the cost (love spending other peeps money!), it complements an already pretty engine room. D44 have a really nice engine room!

Angus99 has a beautiful engineroom setup. Clean and orderly prepurchase. I'm sure its even nicer now.

Click to expand...

Thanks, Jack. It was your initial impression of the boat that gave us the confidence to make an offer. You got to spend a lot of our money that day.

Lou_tribal said:

Shouldn't you double clamp your hoses?

L.

Click to expand...

Good eye, Lou. I couldn't find enough room on the Vetus for two clamps. However, it is secured to the boat with stout number 12 screws and the cushioned hose clamps below it exert considerable resistance against the hoses blowing downward. In addition, these are not high-pressure lines. Most of the raw water hoses on my engines are single-clamped. I'm slowly converting everything to Awab clamps and will be double clamping where that is advisable and possible.

Plus, not under the waterline where double clamping is recommended.