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7. Exhaust Venting
The Optimajor 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 .
The chimney discharge opening must be located at least 24 inches above any part
of the building structure within 10 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.
The “power ventor” system should be installed on the leeward side of the building. Very specific
requirements must be met concerning clearances from combustibles and distances from doors
and windows. Please consult with manufacturer of “power ventor” for this information. In any
case, the “ventor” must be installed by a licensed burner mechanic and done in accordance
with local codes. The B-40 boiler is a very low stack temperature boiler (between 320 and 400F
gross stack 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 using
a listed, “power venting” unit. If “power venting” is used to discharge flue gases, then the power
vent unit should be equipped with a postpurge control as well as delay-off, timing control to
prevent problems with fogging and nozzle post drip.
Note: 88% steady state efficiency is achieved when flue gas contains over 12.5% CO2 and the
gross stack temp. is below 350F.
The smoke-pipe 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, and
sealed with high temperature silicon at each joint. In most cases a barometric draft control isn’t
recommended as the B-40 is designed to be pressure-fired. However, one may be needed if
the boiler is being used in a high draft situation.
7.1 Blocked Flue Switch (Canadian Installations Only)
1. Pierce a 5/8” hole into the vent pipe near the appliance outlet. Remove one of the
securing nuts from the pipe of the safety switch. Tighten the other securing nut onto
the pipe as far as possible.
2. Insert the threaded pipe end into the pierced hole, then install the securing nut, then
install the securing nut, which was removed in step 1, and tighten securely.
3. Please consult the wiring section of this manual for the wiring of the blocked flue
switch.
