re: new boiler advice?
7 mar 1998
steve scott wrote:
>>bruce birbeck wrote:
>>>> john mills writes:
>>>> >you shouldn't be venting an oil burner and gas water heater
>>>> >in the same flue (if you are) anyway.
>>>> i wonder why not...
>>>accidental death, i believe, from asphyxiation.
>>i wonder exactly how that would happen...
>you're having too much fun with this already, nick. :)
well then, how about this?
simple dirt farmer paul writes:
> jan flora wrote:
>>...i used old aluminum road signs behind my stove. aluminum doesn't
>conduct heat. it isn't asthetic, but the cabin probably won't burn down.
>you need an airspace between your wall board and the outer facing behind
>did you mean aluminum _does_ conduct heat??? it is one of the more
>conductive things around. :)
...4x better than steel, 200x better than glass, 100x better than ice
or concrete, and 1000x better than wood or wallboard.
>maybe it works _because_ it conducts the heat to air so well. the heat
>spreads to the whole plate rapidly, no hot spots, so heat can be pulled
>off the whole surface of the aluminum.
that might help with thicker aluminum, but the 4' wide builder's foil
stapled to the wall about 6" behind my 55 gallon drum stove stays very
cool to the touch because it is shiny and reflects, vs absorbs heat.
frank ("mr creosote") duffy wrote:
>>...why not use a double wall chimney with cooler ceiling or attic air
>>flowing down the outside to act as an air-air heat exchanger and cool the
>>flue gases below their boiling point deliberately causing condensation,
>>which runs down the fluepipe back into the stove, as in jotul woodstoves?
>>why further heat and pollute the outdoors?
why not, in fact, control the incoming cold air fan so the outgoing flue
temperature is, say, 150 f, using a cooling snap-action thermostat attached
to the outside of the inner pipe at the top?
>your choice but the trouble is that it just won't do that. the tar and
>creosote will build up inside the flue pipe, choke it so that you risk
>poisonous fumes escaping into your home and if it catches fire then you
>risk the building burning down...
doom, doom, doom.
i wonder why tar and creosote won't do that, ie condense in liquid form and
run back down into the stove at some lowish temperature, vs building up in
solid form inside chimney walls. surely there is a liquid temperature range
for these materials, between gas and solid. an insulated stovepipe can keep
them (mostly) in gaseous form until they leave the pipe, which seems ok but
thermally wasteful and polluting. an uninsulated masonry chimney with cooler
walls might condense them into a liquid which rapidly cools to a solid.
is there a mr in-between?
perhaps this would work better with greener wood, whose combustion products
contained more moisture, or with some fancy stove using water injection. if
the water vapor condenses inside the chimney (transferring more heat to the
chimney walls and the room containing the chimney than a drier flue gas might
by convection alone), and the water vapor never leaves the house, green wood
might heat a house as efficiently as seasoned wood, with a cleaner, thermally
more efficient chimney.