wallas exhaust location

T

tbag

New member
ok so i am about to install a wallas 85 into my 22 cruiser and looking for advice on location and other strategies for minimizing blowback while under way. i was thinking of locating the exhaust outlet father back on the hull ~2 feet back from the sink outlet to hopefully have a little more negative pressure at the exhaust port. also plan on installing a clamshell cover on the outlet to help with water intrusion and blow back. another idea that i have is to have an extra loop in the exhaust tube to make it ~6 feet long to "absorb" and pressure changes. any other ideas out there on installing the my wallas to improve it performance?

thanks

t
 
tbag-

I hear your concern with the possible problems of blowback, smoke in the cabin, water in the exhaust, melted fenders, dock bumpers, etc.

All your proposed solutions would appear to be valid ideas to explore.

However, in my experience, the "smokestack effect" of hot air rising within a tube alone powers the exhaust removal on my Force 10 Cozy Cabin heater without a powered exhaust fan.

I don't have a Wallas, but if IRRC, the exhaust is also powered or fan assisted, right?

So why not just put it through the roof with an appropriate shielded exit cover?

Even if it is a co-axial intake/exhaust double tube set up, I know that roof-mounted intake/exhaust fittings are available that will allow both functions.

Unless you have an inflatable up there or something else that is heat sensitive right at the exhaust point, it would seem more logical there than below the gunnel, IMHO.

Too bad you can't put the exhaust through the rear cabin bulkhead for fear the carbon monoxide fumes would accumulate in the cockpit and re-enter the cabin through the "station wagon effect" at the cabin door.

A co-axial insulated tube could lead the exhaust under the gunnel and out the rear of the boat through the transom, but would probably be too complicated and problem prone to be an effective, simple solution. (KISS Principle)

Good Luck with whatever you do!

Joe. :teeth :thup
 
Look closely at the picture from my photo album. While my boat is a Marinaut, this should not make any difference for a CD22. The exhaust port location, as determined by Les Lampman, is located in the upper portion of the lower hull just below the round window. The port near the strip is the sink drain. We have operated our boat on cold days at 15 to 20 mph with the Wallas providing heat to the cabin without any difficulty. Unless the wind is coming from a bad angle, we don't get exhaust fumes in our boat.


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We installed a clam shell according to the Wallas manual. It does not cover the exhaust port but is mounted just ahead of it to deflect wind from forward motion. We found it worked very well when cruising at 25 kts and above. I could find a photo of it, sorry.
 
The Wallas exhaust is a forced draft (fan driven) exhaust. Thus it is not the same as a natural draft stove where the heat rises in the exhaust thru the roof.

The extra loop will not add anything in safety, but will have more resistance to the flow of exhaust gases. I would not recommend this.
 
It seems like the shortest route out of the cabin makes the most sense, and that's why the factory installed the exhaust port on the gunnel.

Is this a problem that's very common and have there been variations in exhaust location over the years?


We use our boat alot in the cold, and have put countless hours on our wallas 95d in all sorts of conditions. The only "issue" that I can say I've experienced is hearing the sound of seawater going up and down the tube while returning to port in a gale. The sound was the last thing on my mind as we buck and rolled. I guess it could have been the sink drain tube. Otherwise the diesel smell and smoke always stay outside, unless I have the starboard window cracked to let some heat out.

I'd worry about reinventing a design that works for the most part, and creating another problem.
 
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