Direct venting shall be used for condensing type boilers. Both the air
intake and exhaust vents shall be sized and located as indicated on the
drawings and as recommended by the boiler manufacturer. A separate
combustion air intake vent and exhaust vent shall be provided for each
boiler.
2.11.5.1
Combustion Air Intake Vent
The combustion air intake piping shall be constructed of Schedule 40 PVC
per ASTM D 1784. The vent shall be suitable for the temperature at the
boiler combustion air intake connection point. Each intake shall be
provided complete with bird screen.
2.11.5.2
Exhaust Vent
The exhaust vent piping shall be constructed of Schedule 40 CPVC or
stainless steel conforming to UL 1738 and the boiler manufacturer's
recommendations. Plastic materials polyetherimide (PEI) and
polyethersulfone (PES) are forbidden to be used for vent piping of
combustion gases. The exhaust vent shall be suitable for the maximum
anticipated boiler exhaust temperature and shall withstand the corrosive
effects of the condensate. A 8 mm 0.3125 inch diameter hole shall be
provided in the stack not greater than 152 mm 6 inches from the boiler flue
outlet for sampling of the exit gases. A method shall be provided to seal
the hole to prevent exhaust gases from entering the boiler room when
samples are not being taken. Each exhaust stack shall be provided complete
with bird screen.
2.11.6
Expansion Tank
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NOTE: If a hot water heating system is not utilized
delete this paragraph.
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The hot water pressurization system shall include a diaphragm-type
expansion tank which will accommodate the expanded water of the system
generated within the normal operating temperature range, limiting the
pressure increase at all components in the system to the maximum allowable
pressure at those components. The only air in the system shall be the
permanent sealed-in air cushion contained in the diaphragm-type tank. The
sizes shall be as indicated. The expansion tank shall be welded steel,
constructed, tested, and stamped in accordance with ASME BPVC SEC VIII D1
for a working pressure of [850] [_____] kPa [125] [_____] psi and
precharged to the minimum operating pressure. The tank's air chamber shall
be fitted with an air charging valve and pressure gauge. The tank shall be
supported by steel legs or bases for vertical installation or steel saddles
for horizontal installations. The tank shall have lifting rings and a
drain connection. All components shall be suitable for a maximum operating
temperature of 120 degrees C 250 degrees F.
2.11.7
Air Separator
External air separation tank shall be steel, constructed, tested and
stamped in accordance with ASME BPVC SEC VIII D1 for a working pressure of
[850] [_____] kPa [125] [_____] psi. The capacity of the air separation
tank indicated is minimum.
SECTION 15569A
Page 44
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