Where to locate furnace exhaust

[pcg]

I’m soliciting more advice. I’m trying to decide where to place a forced air furnace in my 22 Cruiser project boat, and to some extent that depends on the best place for the exhaust gasses to exit. It would be nice to have exhaust gasses exit straight up a pipe through the rear cabin roof, but that will interfere with other items, like a dinghy stored up there and a stove vent.

Some of the furnaces I’ve looked at come with thru-hull fittings for the exhaust gases. I’ve also seen some instructions say that the exhaust gas should not exit underneath a window that can be opened. That starts to narrow things down.

I’m concerned about exhaust fumes getting drawn back into the boat with windows open, either when anchored or underway. I’d like advice or comments regarding the best place to route exhaust gasses, other than the rear of the cabin roof.

Thank you.

[hardee]

Most of the exhaust outlets are on the Starboard side, just aft of the sink drain. That stbd window does not open, and generally when anchored the breeze will keep the bow pointing into the wind which would carry the exhaust away to aft.

I would be careful to be sure there is clearance away from directly below the midship cleat to allow for using the furnace when at a dock without cooking your fenders.

Harvey
SleepyC

[colbysmith]

What Harvey said. At least that's pretty much where mine is. I have my Webasto mounted underneath the sink. My exhaust port is actually ahead of the sink drain. I've had no problems with exhaust coming back into the cabin with my helm seat window open, although I normally leave that one shut at night because of my exhaust's location. Colby

[pcg]

Thank you both. Very helpful!

[Sea Wolf]

I know you said you didn't want comments about putting the exhaust stack on the rear of the roof, but, to me, at least, that's the most logical, safest place on the boat.

Would placing it there inside a second tube (double insulated) keep your inflatable (and anything else) protected from the heat?

At the same time, the carbon monoxide would be vented at the best possible point on the boat.

Could be a simple stainless or painted steel tube around the usual vertical self-drawing flue tube with the usual top fitting hidden inside.

e.g., put another tube around something like this:



Joe.

[pcg]

[hardee]

Another advantage of the roof stack is that you get the exhaust heat into the cabin for the length of the stack up to the cabin top.

Harvey
SleepyC

[Sea Wolf]

[Discovery]

You don't say what type of forced air furnace? I put an Espar Airtronic D2 in 'Discovery'. It's under the galley cabinet, behind the sink. I also have a Wallas Stove. I exited the Espar exhaust through the starboard side above the walkway and just behind the Wallas exhaust. I don't have to worry about burning fenders as the exhausts are above the walkway and above where fenders are usually placed.

[pcg]

[hardee]

Propane has it's own set of conditions, tankage, storage, venting, servos, just seems like too much "stuff" for a C-Dory. you may hear other comments about it, but for me, I would not consider it on my boat.

Harvey
SleepyC

[pcg]

Thanks for all the suggestions re. where to locate the exhaust. I'm still holding out for some way to get it on the rear of the cabin roof.

[lloyds]

I put a wallas 1300 in the last C Dory 22 I had and went to quite a bit of trouble to make it unobtrusive and route power, fuel and air to best advantage. If I were to do it again I would go the simpler route and just set it on the counter in the starboard rear corner, pointed forward. That way exhaust just goes straight up through the roof, fuel sits on the rear of the shelf under the counter. Really simple, shouldn't take more than an hour so to install. And I think that would have given a better airflow to where you want it, toward the windshield and the v berth.

[thataway]

I agree that there are multiple reasons not to use a propane heater on the C Dory. Be use you know and follow the ABYC recommendations for storage and use of propane, the shut off, sniffers, hoses etc. It is far more complicated than a simple, diesel heater, which uses non explosive fuel. One of the biggest issues is to vent the propane locker overboard. It could be done with a fully sealed aft lazaretto, which. vented over the side at the bottom of the locker.

I used propane fuel for the stoves on our larger cruising motor sailors. But even there, there are many precautions to be taken. Once you have witnessed a propane explosion on a boat, it will leave a lasting impression! I have seen too many--and too many people injured or killed.

[ssobol]