||(This information is based on emission
test results done with a Finnish contraflow heater design
with a grate and air supply from under and in front of
Whether you're a seasoned masonry heater
owner or are reading this as a new owner, there are some
newly discovered firing techniques you will want to
employ to get the most out of your hearth.
- Use regular cordwood! Yes, it is not
necessary to burn sticks 2" to 3"
across to get the rapid, complete combustion that
masonry heaters are noted for. Actually, 4"
to 6" pieces such that 9 to 12 pieces will fill
your firebox when cross hatched will provide better
air/fuel ratio for complete, and more usable combustion.
The bigger pieces allow more time for the masonry
mass to soak up the fire's heat - yielding better
heat transfer to your home.
- Place smaller wood, kindling and paper on top
of this load and light from the top! The
revolutionary top burn greatly reduces emissions
during the dirtiest part of a firing - the first
10 minutes or so. Lighting the load from the top
of the pile yields a candle-like burn, allowing
the firebox to heat up as the volatile gases are
being more evenly released.
- Take a little extra care in laying up your fire.
A good "fuel load configuration" is
well balanced and won't topple over prematurely.
Allow a 1" airspace between pieces, placing
the largest pieces first and the bottom row
running "front to back" in the firebox.
- Don't admit air from below the grate until the
fire is down to coals. Use the air slots in the
door, if provided. If not, cut scrap dimensional
lumber so that a piece will cover the grate and
air is admitted from the front. With a top burn
fire the piece will block grate air until it is
burned through - well into the firing.
Alternately, you can adapt your doors so that
they will 3/4 inch of air between them but can not
be accidentally be opened further. This modification
was lab tested for emissions with excellent
results. During the coal burning phase, rake the
coals so they evenly cover the grate with air coming
- It is more efficient to have one full firing than
2 fires half as large.
If you've been burning small pieces kindled at the
bottom in your contraflow heater, chances are there is
soot in the heat exchange channels. This can effectively
be cleaned from the cleanout door usin a rod and brush
designed for cleaning pellet stove chimneys. This will
better allow them to absorb heat from future fires.
Burning cordwood has so many benefits, economy-wise. And
as you're probably aware, masonry heaters provide the
cleanest burning solid fuel appliances available. Now, following
these simple practices you can be assured that you are
providing yourself and your loved ones simple, yet state-of-the-art
heat more cleanly than ever.