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Old 11-24-2013, 11:55 AM   #1
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Diesel Heater Exhaust Options

I've been reading up on Webasto and similar diesel heaters, as well as diesel cook stoves that offer space heating options. One of these days I'd like to spring for one. However, I have one question that I don't see answered in the spec sheets:

Can I run the exhaust from these low, near the waterline?

I have a genset exhaust on the port side, low on the transom just above the water line. I'm thinking the heater/stove exhaust should go in the same location on the starboard side.

Can this be done?
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Old 11-24-2013, 12:14 PM   #2
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Have always seen them high, thought it was to make sure water did not enter as there is not a lot of pressure with these exhaust lines.
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Old 11-24-2013, 12:28 PM   #3
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Heat rises.

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Old 11-24-2013, 12:55 PM   #4
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Quote:
Originally Posted by CaptTom View Post
I've been reading up on Webasto and similar diesel heaters, as well as diesel cook stoves that offer space heating options. One of these days I'd like to spring for one. However, I have one question that I don't see answered in the spec sheets:

Can I run the exhaust from these low, near the waterline?

I have a genset exhaust on the port side, low on the transom just above the water line. I'm thinking the heater/stove exhaust should go in the same location on the starboard side.

Can this be done?
Negative, ghost rider- the heater exhaust must be located well above the waterline.

Your genset mixes water with the exhaust gases- the heater exhaust does not. Also, you'll need to ensure the exhaust has a loop in the run so water cannot back flow into the heater unit.

On our Wallas, the exhaust outlet is J shaped- the leg of the J points up, and there is a 12" vertical rise in the hose that comes from the heater.
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Old 11-24-2013, 01:16 PM   #5
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I would agree with Pau Hana and I would also add that you find a spot where you don't normally tie a fender. Don't ask how I know.
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Old 11-24-2013, 03:07 PM   #6
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There are a few options with the Wallas exhaust that I did discuss with the the seelers out there in Wash state.. there are a few tricks where you can do things differently than what even their manuals say.

You possibly could locate the exhaust down low...the issue I 'm thinking is the heater isn't crazy about backpressure so if water does keep covering the opening...it may cause problems.

My DT40 has a relatively tiny exhaust (I actually use my fuell vent opening and moved my fuel vent. The exhaust is also not very hot...earlier today I grabbed the exhaust right where it comes out of the heater and it was only barely warm to the touch (the fiberglass sleeve covering)...on high I'm sure it's much hotter but not hot enough to damage fiberglass or char wood.

You really have a lot of flexibility with the Wallas exhaust to where it may exit and it's a small eough opening that it's not unattractive and there's no soot buildup so far (1000 hr of operation) on mine.
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Old 11-24-2013, 03:10 PM   #7
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Negative, ghost rider- the heater exhaust must be located well above the waterline.
There are a couple of reasons for that besides water entering the exhaust, the main one being that the air intake can be coaxial with the exhaust so that the hull is not exposed to high exhaust temperature.
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Old 11-24-2013, 03:33 PM   #8
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Below is a picture of the exhaust fitting on our boat. We have fitted an Eberspacher D2 heater. In our case the air intake is separate, but you can see that it still has a separate cavity around the exhaust outlet to prevent heat damaging the hull.

The fitting goes through the hull on a 45 degree angle upwards and is mounted around 400mm above the waterline. The recommendation was no less than 300mm. The exhaust pipe then rises well above the height of the heater and then down to the heater exhaust outlet. this is to prevent salt water from entering the heater.

I have other photo's of the installation, if that would be helpful to you.

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Old 11-24-2013, 03:55 PM   #9
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There are a couple of reasons for that besides water entering the exhaust, the main one being that the air intake can be coaxial with the exhaust so that the hull is not exposed to high exhaust temperature.
The 40DT takes its combustion air intake from the cabin where it lives. The exhaust is a single pipe. As mentioned earlier, the exhaust is relatively cool on the 40DT, even with the single wall pipe setup.

On the smaller Wallas units and stoves, they use a combined combustion inlet/exhaust.
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Old 11-25-2013, 07:00 AM   #10
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The diesel ranges exhaust thru the deck so more heat is gleaned from the exhaust pipe.

No holes with no closure in the side of the boat.
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Old 11-25-2013, 08:18 AM   #11
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Call Sure Marine in Seattle. They are probably the largest Webasto dealer in the US. Sure Marine
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Old 11-25-2013, 10:50 AM   #12
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Sure marine advised we should install as high as possible and above the rub rail. So we installed mid way from bottom of the window frame and the rub rail, about 4 ft off the water. We had to go up through the salon floor and the out, so I make sort of a fix end table that covered the exhaust which is heat wrapping on it and insulation.

My advise to to use an installer as he can buy the parts at wholesale and sell thme for the same price you would buy retail. Plus they will help with the system design, sizing and the final installation.
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Old 11-26-2013, 03:17 PM   #13
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>So we installed mid way from bottom of the window frame and<

Be sure to NEVER open that window when the heater is operating.

You could end up Dead or a Democrat!
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Old 11-27-2013, 01:33 AM   #14
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AHaaaaa FF "My Father was a life long Republican. He voted Republican every time till he died. Now he votes Democrat every time"

Pete- Pa-Hana- Great news!! Fired up the DT30 this afternoon first time. Called Doug at Scan Marine knowing he was relieved to hear that everything went as designed. I mentioned that you had been instrumental in my making the decision to replace the obsolete Espar DL3 with the Wallas.
As to the exhaust questions. As I had thought a unique route for an exhaust I discussed with both Doug and Bruce at Wallas Heater | Boat | Stoves | Cooking Equipment | ScanMarineUSA.com

When I asked for 9 feet of exhaust there followed a pregnant pause where upon I was refreshed with the knowledge that there is a limit of 6 feet for the DT30 exhaust and within that length there "MUST BE" a 12 " loop as described in other above post.
After "Redesign" I was able to achieve the desired loop and more by relocating the hull outlet and destroying the interior of a cabin cabinet. In all honesty, this is a snap unit to install.

Thanks again Pete, I mentioned you name. Do you own them money? 8-) Joking, honest it is a joke. pleased that you are active on their behalf and products.
you have been a real help and this forum is just the cats meow for information

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Old 11-27-2013, 01:40 AM   #15
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Nope, no affiliation, Al- just a satisfied customer.

My office was next door to Scan Marine for 12 years- I know the original owners of the business, and have a great relationship with Bruce and Doug, the brothers who own the business now.

I looked at all the heating options out there, and found this one the best for our needs.
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Old 11-27-2013, 06:31 AM   #16
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Even the 12 inch loop isn't mandatory after discussing it with Scanmarine...just that it goes far enough uphill that a direct spray won't be able to force water all the way back to the heater and that portion is a downhill run to drain back out.

So different installation setups are possible if you need them to be.
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