HearthStone Nestor Martin S31 Owner's Manual page 5

Atmospheric influences
Wind blowing across the flue cap can increase the negative pressure within the flue proportionate to the wind
speed. Because wind speed is never constant, the varying effect this may have on the stove would be
unacceptable. To control this, the stove is fitted with a draft stabilizer. When the negative pressure
from the stove. This will reduce negative pressure in the flue to fall within acceptable limits. When the wind
speed decreases, the stabilizer will close to return the full negative pressure of the flue to the stove. During
initial start up, the negative pressure within the stove is measured and the stabilizer is adjusted to suit the
characteristics of the flue thus ensuring optimum control.
If the flue terminal is too low in relation to the roof or is masked by other buildings, it is possible for winds
coming from certain directions to become so turbulent that the stove's stabilizer will be unable to respond
quickly enough to the changing conditions. Trees often create turbulence problems and are frequently
overlooked. Not only do the aerodynamics of trees change with the seasons and leaf growth, but a large tree
may have no effect for many years yet its last foot of growth may cause a previously well controlled stove to
become erratic. No termination cap can be installed on the flue terminal which will overcome all possible wind
turbulence, but minor turbulence can often be reduced to acceptable levels with a suitable model. For major
turbulence problems, increasing the height of your existing flue or altering the existing problematinc conditions
will be the only effective cure.
The term down draft is often used erroneously to explain away almost any flue which is unable to sustain
sufficient thermally induced gas speed. In most instances, this condition is caused by an insufficient flue which
allows the flue gasses to cool too much and a cure may be a simple as installing insulated pipe. True down
draft affects houses situated on or near to hills, when cooling air travels down the hillside.
This coditioin can normally be controlled with an efficient flue system and suitable termination cap. If, however,
the wind causes a high pressure zone at the flue terminal, relocating the flue to the opposite side of the house
may be the only effective answer. The opposite condition, when warming air travels up a hillside can produce
very high negative flue pressures which will sometimes necessitate a barometric damper being installed on the
flue.
Windows and doors opened down wind of prevailing winds and the running of large exhaust fans without
adequate ventilation may cause the flue to stall or even become positively pressurized with potentially
dangerous consequences. Any smell of flue gasses within the house should be investigated immediately.
Damp weather is one of a multitude of atmospheric conditions blamed for poor flue draft. There is no
theoretical or practical foundation for many of these atmospheric causes, only the existence of an oversized,
cold and damp chimney needing lining and/or additional insulating.
Ventilation (Make Up Air)
Providing sufficient ventilation to supply a stove with air has to be regarded as an integral part of the flue
system. Unless the air passing through the flue is replaced with an equal amount of air entering the house, the
flue will cease to function. The colder the outside temperature and the harder the stove is working to maintain
the required temperature inside, the colder the incoming air and the greater its flow.
Any room or space containing an appliance should have a permanent ventilation opening of free area at least
2
550 mm (0.8525 square inches) for every kilowatt (3,412 BTU) of rated output above 5 kilowatts (17,060 BTU)
OIL BURNING APPLIANCES SHALL BE CONNECTED TO FLUES HAVING SUFFICIENT DRAFT AT ALL
TIMES TO ASSURE SAFE AND PROPER OPERATION OF THE BURNER.
When install the S31 always use a quality 4" L vent pipe. This will help to ensure your draft requirements are
met.
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