Diesel Heater Setup

[GordMay]

Originally Posted by Leighpilot

Do not draw the combustion air from inside the boat. Think about it. The combustion air becomes the exhaust air and is vented over the side. So as much air is exhausted outside, as much air , cold outside air , must be drawn into the boat. So while you are warming the air inside the boat , you’re continually drawing in cold outside air , not terribly efficient. So make sure you draw combustion air from outside.

When installing combustion appliances within a boat’s conditioned space, the safest, and most energy efficient type is a direct-vent, sealed-combustion unit.

These appliances eliminate the possibility of backdrafting, which occurs when the products of combustion, including carbon monoxide, are drawn back inside the boat, through negative pressure.

A direct-vent sealed-combustion furnace, boiler, or water heater brings combustion air directly from outdoors, to the sealed combustion chamber, through one sealed pipe, and exhausts the byproducts of combustion [carbon dioxide and nitrogen] to the outdoors, through a second sealed pipe.
These two pipes [intake & exhaust] may be combined, in a single “co-axial” [pipe within a pipe] vent.
The exhaust travels through the inner pipe to the outdoors, while the outer pipe allows the fresh air [for combustion] to come in, and be transmitted directly into the bottom of the sealed combustion chamber [firebox], where it ignites the unit. The outer pipe also helps insulate any surrounding combustible components from heat travelling through the system.

The Wallas “Viking” and “ Spartan” Diesel Air Heaters, for instance, are available with co-axial direct venting.

[Pizzazz]

Keep the combustion air loop separate, also for safety. Watch out the combustion exhaust outlet and the outside fresh air intake positions... sometimes the wind may blow smoke to the fresh air inlet, and you can smell it. Not a good idea.

Take air from the cabin, heat it, then return it. There are plenty of openings to refresh the air and you can always open a hatch for ventilation when you need it. Some people worry about running out of oxygen in a water tight compartment/boat. I would not but it is always better just to open a hatch a bit.