Exhaust Venting; Common Exhaust Venting - Biasi SG 2 Manual And Installation Instructions

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The SG boiler is a high efficiency unit that requires proper venting. The boiler must
be vented to the outdoors by means of a tile lined masonry or an approved pre-fabricated
chimney of the size and height recommended by the manufacturer or by a listed "power
venting" unit which provides draft by mechanical venting. In many installations, particularly
older interior and most exterior chimneys, a corrosion resistant liner should be installed.
Please consult liner manufacturer for the appropriate chimney liner.
The chimney discharge opening must be located at least 24 inches above any part of the
building structure within 4 feet of the chimney. Be sure the chimney and smoke pipe don't
become obstructed by squirrels, bird nests, soot buildup, chimney liner deterioration, etc.. If
using a "power venter" system, it is suggested that it should be installed on the leeward side
of the house. (Please consult with manufacturer of "power venter" for requirements
concerning clearances from combustibles and distances from doors and windows.) The
"venter" must be installed by a licensed burner mechanic and done in accordance with local
codes. This is a very low stack temperature boiler (350F gross temp.) so caution should be
used when connecting to an outside built chimney. Should you have concern that the flue
gases could condense, then you should consider lining the chimney or using a listed, "power
venting" or " direct venting unit". If "power venting" is used to discharge flue gases, then the
power vent unit should be equipped with a postpurge control such as a delay-off, timing
control to prevent problems with fogging and nozzle post drip.
The determining connection from the boiler to the chimney should be as short as
possible, with a minimum number of elbows. The vent pipe must have a vertical rise of at
least 1/4 inch per foot of horizontal run. The vent pipe must be of the same diameter as the
flue outlet on the boiler. The chimney connector should have a minimum thickness of 24
gauge, corrosion resistant (galvanized) steel, assembled with a minimum of three (3) sheet-
metal screws in each joint. In some houses, a barometric draft control isn't required as the SG
is designed to be pressure-fired, however in high draft situations which exceed the flue gas
resistance through the boiler, a barometric draft control is recommended. The over fire draft
should be between 0 and .06 inches of water column. The draft at the breech should be
enough to overcome the over fire draft at all times.
Common vent exhaust:
If this boiler is replacing one that was part of a common venting system, it is likely
that the vent is to large to vent the appliances still attached to it. To prevent this, at the time
of removal, the following steps shall be followed with each appliance remaining connected to
the common venting system. Place each unit in operation, while the other appliances remain-
ing connected to the common venting system are not in operation.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and horizontal pitch and deter-
mine there is no blockage or restriction, leakage, corrosion and other deficiencies
which could cause an unsafe condition.

7. Exhaust Venting

7.1 Common Exhaust Venting

Biasi SG Series