Has anyone installed a diesel heater in their 310/315?

May 1, 2011
5,464
Pearson 37 Lusby MD
I need to figure out how to update my profile. My boat is a Catalina 310.
In the upper right of the screen, you should see your SBO login name. Click on that, then on account details, and you should be able to update your profile.
 
Apr 5, 2009
3,301
Catalina '88 C30 tr/bs Oak Harbor, WA
I need to figure out how to update my profile. My boat is a Catalina 310.

Autoterm claims in the manual that the exhaust line shipped with their kit is suitable for marine installs including their silencer. I will be carefully monitoring CO in the installation compartment with my low-level CO meter (measures down to 10ppm).

I do plan to do the condensation drain next. I've read varying/conflicting feedback if they're needed in the moderate ~50 degree F environments I'm running in. It will add a handy 90 degree bend which will allow me to get more "hump" in my exhaust for back-flood presentation.
Did you watch the video that Maine Sail made that is linked to in post #15? If it is stamped /edge crimped metal and not 100% welded construction it will leak which can be deadly. If you have a short piece of the flex pipe left over, I would unwind it to see if it is double wound. With this type of pipe, the middle of one wrap overlaps the middle of the previous one so that there are always two layers of stainless steel. Just because a mfr says marine does not mean it is safe for marine use.
 
Jul 28, 2024
73
Catalina 310 238 Berkeley, CA
Did you watch the video that Maine Sail made that is linked to in post #15? If it is stamped /edge crimped metal and not 100% welded construction it will leak which can be deadly. If you have a short piece of the flex pipe left over, I would unwind it to see if it is double wound. With this type of pipe, the middle of one wrap overlaps the middle of the previous one so that there are always two layers of stainless steel. Just because a mfr says marine does not mean it is safe for marine use.
Thanks! I will do the test with the flex pipe.
 
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Jul 28, 2024
73
Catalina 310 238 Berkeley, CA
The crimped silencer in that video is indeed scary! Here's a picture of the Autoterm one, it is welded all around:
3944new.jpg



Here's a close up of the one in my boat, before I removed it due to the back-pressure issue:
Silencer.png



I also see what you mean about the single-wound pipe in the video. The pipe supplied with my kit was much thinker. I'll take a pic of the profile when I get a chance.
 
Apr 5, 2009
3,301
Catalina '88 C30 tr/bs Oak Harbor, WA
Thanks! I will do the test with the flex pipe.
The automotive flex pipe is attached edge to edge, so it is one layer thick. The marine flex pipe is attached edge to center so that it has 100% overlap for two layers full length.
You could test your silencer to see if it has any leaks. The simple test is to put your palm on one end and blow into the other to see if it leaks. The crimped ones have massive leads and a drain hole that is just wide open.
My Espar was extremely loud when I first installed it so I got one of the welded marine mufflers and the difference was amazing. It went from sounding like a 707 doing a runup to a bare whisper.
 
Jul 28, 2024
73
Catalina 310 238 Berkeley, CA
Good description. I' now confident I've got marine flex pipe. I've seen photos of the cheap edge-to-edge stuff you're talking about.

When I work on it again, I plan to install this Espar 24mm Marine Exhaust line that I got from HEATSO. It has the cylindrical silencer in the middle and the rest of the line wrapped in insulation inside an outer jacket. It wasn't cheap, but using that dusty exhaust wrap line is something I want to never do again.
292199014506_1__43055.jpg


By the way the 24mm line in the middle of this assembly is exactly what the one that came in my kit looked like.
 
Jul 28, 2024
73
Catalina 310 238 Berkeley, CA
Now that I'm back to thinking about this, I took apart that Espar insulated assembly to see what things look line inside:

Exhaust_Assembly_1.jpeg

Exhaust_Assembly_2.jpeg

Exhaust_Assembly_3.jpeg


Seems like 24mm marine exhaust hose, a nice looking but very long (maybe 18" silencer), all wrapped in a sock and then the thin outside tube. It's not exactly "one piece," there is clearly some sealant where the exhaust hose enters and leaves the silencer, but it does seem well built and well sealed.

I'm not sure I'll get this to fit into my compartment, but going to try.
 
Apr 5, 2009
3,301
Catalina '88 C30 tr/bs Oak Harbor, WA
The exhaust silencer for our heating system is all welded and insulated with a fiberglass sock filled with insulation. These came from Sure Marine.


View attachment 237359

View attachment 237358
This is the same setup I have except that I got the welded muffler from ebay for well less than Sure Marine charges. Their boat tax is pretty high.
Now that I'm back to thinking about this, I took apart that Espar insulated assembly to see what things look line inside:

View attachment 237352
View attachment 237353
View attachment 237354

Seems like 24mm marine exhaust hose, a nice looking but very long (maybe 18" silencer), all wrapped in a sock and then the thin outside tube. It's not exactly "one piece," there is clearly some sealant where the exhaust hose enters and leaves the silencer, but it does seem well built and well sealed.

I'm not sure I'll get this to fit into my compartment, but going to try.
That is a nice looking exhaust and about what Sure marine charges for just the muffler.
 

VFR750

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Oct 18, 2021
61
Catalina 315 Noank
This is great information. It really helps thinking about which system and what's required.
 
Jul 28, 2024
73
Catalina 310 238 Berkeley, CA
I found a picture of the currently installed exhaust. This is what I changed to after my original setup with the silencer had too many bends and too much back-pressure.

IMG_1476.jpg


I thought it would be loud without a silencer, but it's not. The exhaust points straight out behind the boat, and I don't think with the sound of the water passing under the transom we'll be able to hear it at all while sailing. I can see how a neighboring boat in an anchorage might be annoyed if it was pointed directly in their direction, but that's not a use case for the foreseeable future.

The fancy Espar exhaust with the silencer in my post above might just be too big for this space - the silencer is nearly 18" long. I think it might result in a bunch more bends and I'll be back to the back-pressure problem.

If I had it to do over again, I'd mount the heater higher so that I have more natural flooding protection and don't require that S-curve to get the exhaust connected to the bottom of the heater.
 
Jul 28, 2024
73
Catalina 310 238 Berkeley, CA
A quick note to say that after the 700NM run down the Pacific cost, and a cold 4th fireworks anchoring session in SF with my partner, the heater has been deemed to be a champ. The little 2Kw model will bring the aft berth and head (the only locations to where I ran vents), up to approximately one million degrees and warm the rest of the cabin up too if the companionway is closed up. This is all in approximately 50 F external temps. Operation is dead simple, I leave it on high all the time based on wisdom read elsewhere. There is a slight stink in the cockpit during the first few minutes of use, but that goes away quickly. I never did add a silencer (see above), but the sound is not bothersome over the normal sounds of sailing.
 
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