Installation manual

Page 28 IM-487
Unit Piping
Gas Piping
See the "Installation" section of the gas-fired furnace installa-
tion manual, Bulletin No. IM 684 or 685.
Fuel Oil Piping
See the "Installation" section of the gas-fired furnace installa-
tion manual, Bulletin No. IM 684 or IM 685.
Piping for Steam, Hot Water / ChIlled Water Coils
Factory installed chilled water coils are installed in a coil sec-
tion which may be designed to accept a factory installed heat-
ing coil immediately upstream. The coil section may be
ordered in either the draw-through or blow-through position.
All chilled water piping can be done internal to the unit with-
out requiring a piping vestibule (except on sizes 800-802 when
heating coils are included in the cooling coil section).
Steam and hot water coils may be factory installed in either a
heat section, or in the combination coil section. These sec-
tions may be located either in the draw-through or blow-
through position. When a steam or hot water coil is installed
in the heat section, all piping may be done internal to the unit
without requiring a piping vestibule. Refer to Figure 29 and
Figure 31 on page 30.
When a steam or hot water coil is installed in the combina-
tion coil section, the coil connections project to the inside
surface of the door panel. Holes may be cut in the door pan-
els for the piping to be connected to the coils, or an accessory
piping vestibule may be added to the unit to provide piping
space. Refer to the section on vestibule assembly instruc-
tions. The piping may then be routed back within the unit as
shown in Figure 29 on page 29.
To avoid piping penetrations through the roof external to the
curb, holes may be cut through the floor of the unit at the
locations specified on the cer1ified drawings.
Figure 27. Valve Assembly
Note: The valve actuator spring returns to a stem up posi-
tion upon power failure. This allows full flow
through the coil.
Hot Water Piping (All Units)
Note: If an iron valve is installed in the unit, connecting to a
copper piping system will likely cause galvanic corrosion to
occur and the valves will not last. All coils have vents and
drains factory installed.
Hot water coils are not normally recommended for use with
entering air temperatures below 40°F (4°C). No control sys-
tem can be depended on to be 100% safe against freeze-up
with water coils. Glycol solutions or brines are the only
freeze-safe media for operation of water coils for low enter-
ing air conditions. Refer to the "Maintenance" section of this
manual for more on winterizing coils. The hot water section
consists of two stacked coils, as shown in Figure 28. When
no factory piping or valve is included, the coil connections
are 2.12" ODM copper.
Hot Water Piping to Coils In the Heat Section
Hot water coils are provided without valves for field piping,
or piped with three-way valves with actuator motors.
With the factory piping and valve package, the two coils are
piped in parallel and controlled through a single three-way
valve. Field piping connections are of the same NPT size as
the valve-male threads at the supply connection, female
threads at the return connection.
CAUTION
All holes in the unit floor must be sealed to prevent
water leakage into the building.
CAUTION
Coil freeze possible. May damage equipment.
Carefully read instructions for mixing the antifreeze solu-
tion. Some products will have higher freezing points in
their natural state than when mixed with water. The
freezing of coils is not the responsibility of McOuay
International. Refer 10 "Winterizing Coils" in the "Main-
tenance" section of the manual.
S t e m
S e t s c r e w s
S t e m C l i p