GBlist: Fireplaces - the burning debate...

["Bion D. Howard" <bdhoward@ix.netcom.com>]

An elegant solution is to employ a _real_ masonry heater rather than those
(sometimes) crappy zero clearance units loved by typical production
builders.  

Recently in Northern Virginia several homes either burned or had close
calls where zero-clearance fireplaces failed  --  (failed to be installed
correctly says industry... failed to be properly designed and engineered
says builders...glad nobody died said the homeowners...show me the money
say the attorneys....).

Another myth is that masonry fireplaces are all "big" energy losers, but of
course this is not true despite a bunch of marking hype on both sides of
the issue (block and brick folks versus the "fireplace industry").  

The key thing is how combustion air and excess air get supplied to the
burn, and whether the unit can be sealed from the conditioned space during
and after use.  Air to the combustion process is just physics and can't be
tampered with -- only accommodated.

   1.  if the supplies of air necessary for combustion/excess come from the
conditioned spaces, you are begging for smoke, soot, smell, and ultimately
(when the JennAir grill, bath fan, and the clothes dryer are all on...)
flame roll out and/or CO evolution in the space from other combustion
equipment  (( BAD )).

   2.  if modern installation practices are followed (or retrofitted to an
existing house) then the air supply to the combustion process is largely
provided from outdoor sources.  Some indoor air will still be lost  along
with its heat up the flue, but at least the burn is not "sucking" 7 to 10
PA from the (tight)  home.

  3.  a masonry heater or good quality wood stove/wood stove insert will
(should) always have _both_ outside air supplied, and a way to securely and
tightly seal the doors or fire place view area.

  4.  in winter -- especially after a she-dog Blizzard like we just had
roll through Annapolis w/20 inches of Eskimo snow -- it is vital to clear
the air-inlets to heater / wood stove just as you would for other systems
like side-vent stack for a sealed combustion furnace or water heater.

I can't debate the efficiency of masonry heaters, wood stoves or
"fireplaces" since there are too many variables and general numbers range
from about  -25% loser to 40% efficient depending on source.  I have even
seen higher claims for "Russian fireplaces" but no supporting data.  A
great source of info is the Masonry Heater Association.

What I can tell you is that on many plan sets we review, the issue of
fireplaces, wood stoves etc. always comes up -- people just like them and
also feel that when they go to sell the market will "expect" the thing to
be there.  So we in the energy design, building science and "green" areas
need to learn how to cope with the issue, since it's not going to go away.

    <<<  that concludes my cardiac arrest break
                from excess snow grovelling,   Bion

    ||       Contact:  Bion D. Howard, President
=(O) =     Building Environmental Science & Technology
    ||      P.O. Box 1107   Edgewater, MD 21037  USA
         Phone:  410.867.8000   Telefax: 301-889-0889
<mailto:bdhoward@ix.netcom.com>  <http://www.energybuilder.com>
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