Installing a Wood Burning Stove: Part III
With the deck iron in place, it is time to work out the details of setting the stove in place and fitting the flue pipes. The enclosure from the original kerosene heater is lined in asbestos and requires some modification to make it more effective. Basically, the floor of the enclosure needed to be raised and leveled, and the space below converted to a short term fuel storage spot. A simple carpentry effort made short work of that.
I've re-used the asbestos sheets that lined the space. Asbestos is very dangerous as dust, but as long as it is stable, it presents no health hazard. Reusing it involved making a few cuts (dust), but also keeps the material out of the landfill, so the tradeoff seems reasonable to me.
The alternative to asbestos is to create a heat shield which is comprised of sheet metal (typically copper or stainless steel) offset from combustible surfaces by an air barrier (1 inch is the standard recommendation). In designing mine, I educed that air space to 1/2 inch as the enclosure is already lined with asbestos.
Before patterning the heat shield I worked out the flue design as I wanted the heat shield to track the configuration of the flue in an esthetically pleasing (and safe) configuration.
The flue is made up of 3 inch diameter stainless steel components readily available from the local chandlery. I needed two standard lengths of flue pipe, two 45-degree elbows, a manual butterfly damper, connected so as to bring the flue gases from the stove to the deck iron in a dogleg fashion.
Cutting the flue pipe is simple with an angle grinder set up with a cutting wheel. Flue pipe comes with a crimped end and a plain end, and you need one of each end type at every connection. It was fairly strait-forward to get it all to fit together, and the elbows afford sufficient wiggle room to cheat a bit.
With the flue pipe assembly in place, I then used a piece of cardboard to make a pattern for a stainless steel heat shield that I had fabricated at a local sheet metal shop. The single piece shield has a wrap-around configuration inside the enclosure, and then rises to the cabin top in a dog leg that echoes the flue so as to reflect heat from the flue pipe away from the combustible surfaces.
I also patterned a finish piece at the top to hide the place where the deck iron intrudes into the cabin, and to provide additional heat shielding. Fitting, drilling, and fastening this finish piece took up a disproportionately large part of the installation time... and many trips to the hardware store and chandlery!
|Stove and heat shield installed|
There is an additional section of flue pipe that extends above deck and terminates in a flue cap to keep water out and attenuate wind gusts. I arbitrarily used the remaining section of flue pipe for this (about 18 inches). I may cut it down to something closer to 12 inches, which seems to be a consensus for such installations.
In theory, the longer the flue, the better it should draft, but other above-deck appurtenances will influence what is practical in any given installation. Every installation will be customized to accommodate the specific requirements of a given situation.
I elected to install a manual butterfly damper to help regulate the burn rate of the stove. A built in damper on the stove affords an additional control point. It is very important to have the means to prevent a runaway stove... a stove burning too hot. I will also have a container of sand in the event things really do start to get out of hand, and obviously a fire extinguisher close at hand is essential.
Anyone who would install any kind of stove in a vessel without CO monitoring and smoke detector is foolish and irresponsible.
One flue component I did not install is a barometric damper. I may yet add one, however. The idea is to minimize back draft from gusting winds that can force smoke back down the flue and into the cabin. My initial test run was on a windy day (today), and I did experience some momentary back draft.
I burned the stove for perhaps two hours, and am very pleased with the result. The flue quickly becomes too hot to touch, but the heat shield never got beyond warm even very close to the stove. I am very pleased with how well it isolates the stove from nearby surfaces.
I'm not sure what my fuel of choice will be. Today I burned wood scraps, but they burn quickly and with a fair amount of ash. I will experiment with charcoal briquettes, small pieces of fireplace logs, perhaps wood pellets, and maybe even coal. The firebox of the Pet is quite small -- not a fire that will last though the night, but it should be quite effective at keeping the boat dryer and more cheerful.
Time for a late-winter cruise!
One final note. I'm no expert. This is my first stove installation. I have deviated from standard recommendations in several respects, and done so fully cognizant of the risks. No one should start a fire on a wooden boat... on any boat... without clear eyed consideration and management of every aspect of the hazard.