Diesel heater exhaust

I just recently had a diesel heater installed (Planar 8D). Due to the design of my boat we were able to position the exhaust only 12" above the waterline on the aft starboard side. The exhaust tube does rise some as it passes through the lazarette which hopefully would deny water reaching the heater should we be hit hard by a large wave. Is anyone aware of any type of "flapper" which can be attached to an external exhaust (1.5" approx) to prevent water incursion?
Thank you for your responses.
re: Planar heater; so far so good. Forcefully pushes copious hot air.

how long is the exhaust tube and what is the diameter?


Wallas advised the rise is less important the longer the run.

Marine exhaust flaps like those made by Centek use a rubber flapper, which probably won't stand up to the higher temp of tyour heater exhaust. And 2" is the smallest that Centek makes.


Your problem is exactly like the exhaust from a lift muffler- so route it up in a loop as high as possible before dropping down to the outlet fitting.


I had a heater installed in a sailing cat with a similar distance above the waterline to the outlet. The exhaust was routed about a foot higher before it dropped down to the outlet.


David

We had an Espar that exited Hobo about 8" above the water at the stern. We did the same as David mentioned: the exhaust run was much higher then the exhaust at the hull.

We also had a wood plug that we plugged the exhaust outlet from the outside when we weren't using it. I pulled an inline fuse for the unit and hung it on the wall so I wouldn't forget.

Mine is a Webasto and exits low on the stern and when under way I plug it with a rubber expansion plug hung on lanyard above when not in use. Has worked fine for 18 years. I have heard caution from some about being aware with the side vented exhausts to be careful if ever rafted up to another boat due to the heat. Just in case?

Sorry, I read your post wrong and see that it is (aft) starboard like mine. Not on the side though I have seen some like that

We have an expansion plug for our exhaust as described in a previous post. I think the only time I installed it was coming up the coast from So Cal. Obviously you can't run the heat with it installed, and need to remember to remove it before firing back up again.

You should be able to get an appropriately sized one from Sure Marine in Seattle.

Like many I recommend a plug. When cruising our hydronic heater utilizes engine heat so diesel heater is off and plug can remain in place.

exhaust port

theplug sounds like a good idea, on my boat the PO installed the exhaust port for the espar 2" above the water line one of the first things I changed. Now 12" above waterline- couldnt place it higher I think it can be seen on my avatar

They sell some kind of draining "T" that can be added to the low spot in the exhaust. Seems like it might help with condensation; I suspect there would be a lot if you didn't run it long enough at high temperatures. I did get a plug for the outside vent, and did an elevated loop in the exhaust hose to it. No underway experience with it yet.

RNL said:

Mine is a Webasto and exits low on the stern and when under way I plug it with a rubber expansion plug hung on lanyard above when not in use. Has worked fine for 18 years. I have heard caution from some about being aware with the side vented exhausts to be careful if ever rafted up to another boat due to the heat. Just in case?

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Be careful where you place your fenders also. We were walking up the dock in LaConner one evening when I smelled hot plastic. There was a boat with a fender in front of the heater exhaust and it was melting. The owners were very surprised. When rafting, the boats in our club plug in a stainless 90 deg. tube to direct the heat away from the boat beside them. Sure Marine sells them.

Thanks for all your responses. I'll be looking for a plug I spect. Can someone be more specific regarding the "plug". I expect anything that plugs the hole is sufficient however are you using wood, rubber, dense foam or ??
Addtl info: length of exhaust run is over 10', diameter of exhaust tube is 42mm

I have one thing similar to this - Shaw expansion plug , found on google search. I'm sure there are many that will suffice.

petdoc4u said:

Can someone be more specific regarding the "plug".

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$5.50 on Amazon:

The plug required on many setups has to cover two holes, the outer and inner variety for instance. Exhaust and air intake plumbed together in same two compartment pipe.

Thank you to everyone who posted a reply. Ordered ($5.50) a motorcycle exhaust plug on Ebay. The exhaust fitting elbow is an interesting idea. My only concern is smacking it into a dock should a fender not be in place.
Cheers

petdoc4u said:

Thank you to everyone who posted a reply. Ordered ($5.50) a motorcycle exhaust plug on Ebay. The exhaust fitting elbow is an interesting idea. My only concern is smacking it into a dock should a fender not be in place.
Cheers

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The elbow would only get plugged in after you are rafted or docked. When under way it would be removed. The ones I have seen just slip in the exhaust pipe and are held in by friction. A safety lanyard is a good idea, just in case it slips out.

I had my pipe threaded so I could screw on a SS cap when not running and an extension to elbow pointing down to keep heat away from hull plus possible shout mark. The exhaust heat can blacken a dock face.