Midco Unipower G-Series - Manual (Page 6)

WARNING: The chimney shall be inspected for unsafe conditions such as deteriorated
masonry and excessive soot or other blockage or potential blockage. Installation must
conform with local codes or in the absence of local codes with NFPA, ANSI Z223.1-latest
e d i t i o n .
WARNING: No movable vent connector damper is permitted on any gas conversion
installation. The chimney should be inspected for unsafe conditions such as deteriorated
masonry and excessive soot or other blockage or potential blockage. Check your local
authorities for regulations covering barometric draft regulators on gas equipment.
WARNING: The vent connector shall not be connected to a chimney already venting solid
fuel burning equipment, an incinerator or an open fire place.
■ ■ The Unipower burner does not depend on chimney draft. Combustion air is supplied by the forced air
blower, which is sufficient to supply adequate air for any normal boiler. This reduces the function of the
chimney to removal of flue products from the boiler. A chimney height of 15' above the boiler flue
outlet will generally prove ample if the recommended or larger vent connector and chimney diameters
are used. The chimney must of course, extend several feet over the roof of the building, or adjacent
buildings. Vent connector material should be 24 gauge or heavier steel, galvanized to resist corrosion.
The horizontal run of vent connector should be pitched upward from the appliance flue outlet at least
1 / 4 " to the foot. Avoid excess elbows or other constructional features that would create excessive
resistance to flow of flue products. Fasten joints with sheet metal screws to prevent sagging. The vent
connector should be maintained at least 6" from combustible building materials; more if it is
uninsulated. Where it passes through partitions constructed of combustible materials a ventilated
thimble should be used. Refer to your local building codes. The vent connector should be firmly
cemented into the chimney but
must not extend beyond the inner
face. Where two or more
appliances use the same chimney,
be sure not to enter the chimney
with both flue pipes at the same
l e v e l .
■ ■ Do not arbitrarily reduce the
vent connector size, since a boiler
back pressure can build up, leading
to possible leakage of flue products
into the boiler room.
■ ■ Chimney construction can be
either of brick, preferably tile lined,
or of steel. Joints in the chimney
should be smooth and leak free to
prevent uncontrollable air
infiltration. They should be made
so that condensation if any, will
not collect in the joints or leak to
the outside.
■ ■ If the vent connector must be extra long, the area of the pipe and chimney should be increased or
the chimney height must be increased, or both. Never allow the horizontal length of the vent connector
to exceed the height of the chimney.
Figure 8: Firing Door Installation in Three Pass Boiler
III Combustion Chamber
Continued
IV Chimney, Vent Connector
and Draft Control
Figure 9: Recommended Locations for Draft Hoods