intermittent type with automatic electric ignition. The pilots shall be of
the electrically-ignited proven type. Continuous pilots will not be
permitted. Burner shall be designed in accordance with NFPA 54 and located
so that parts are protected against overheating. Provisions shall be made
in the burner housing for inspection of the pilot flame.
2.2.3.2
Oil-Fired Units
Ignition systems for oil-fired units shall be of the [direct-electrical
spark type] [direct-electric spark type or interrupted type] in accordance
with UL 296.
2.2.4
Supply Blowers
Blowers shall be centrifugal type. Blowers shall be statically and
dynamically balanced. Lubrication points shall be located or extended, as
required, to provide ready access for periodic lubrication. The direction
of rotation shall be clearly and permanently marked on each blower housing.
Blower speeds shall be single, or multispeed, as indicated, to provide the
specified range of air temperature rises. Direct-drive blowers may have
multiple speed motors to change blower speed. Belt-drive blowers shall be
provided with an adjustable base and guard or enclosed in the unit casing.
The belt drive shall be designed in accordance with the applicable Rubber
Manufacturer's Association (RMA) power transmission belt specifications,
with a service factor of at least 1.2. Shafts shall be supported by a
minimum of two self-alining bearings. Blower speed shall be adjusted by
the use of variable pitch drive sheaves.
2.2.5
Vents for Conventional furnaces
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NOTE: Delete this paragraph if high efficiency
furnaces are specified.
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A 8 mm 0.3125 inch diameter hole shall be provided in the vent stack not
greater than 152 mm 6 inches from the furnace flue outlet for sampling of
the exit gases. A method shall be provided to seal the hole to prevent
exhaust gases from entering the indoor space when samples are not being
taken. Each exhaust stack shall be provided complete with bird screen and
rain hood.
2.2.5.1
Gas-Fired Units
Vent piping shall be in accordance with UL 441, [Type B] [Type BW]. Vent
shall conform to NFPA 211 and NFPA 54. Plastic materials polyetherimide
(PEI) and polyethersulfone (PES) are forbidden to be used for vent piping
of combustion gases.
2.2.5.2
Oil-Fired Units
Vent piping shall be in accordance with UL 641, Type L. Vent shall conform
to NFPA 211. Plastic materials polyetherimide (PEI) and polyethersulfone
(PES) are forbidden to be used for vent piping of combustion gases.
2.2.6
Vents for High Efficiency Furnaces
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NOTE: Delete this paragraph if gas-fired high
SECTION 15566A
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