Installation manual

32 McQuay IM 487-4
Introduction
Hot Water Piping
Hot water coils are provided without valves for field piping or
piped with three-way valves and 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.
Hot water coils are not normally recommended for use with
entering air temperatures below 40°F (4°C). No control system
can guarantee a 100% safeguard against coil freeze-up. Glycol
solutions or brines are the only freeze-safe media for operation
of water coils at low entering air temperature conditions. Refer
to the “Maintenance” section of this manual for more on
winterizing coils. The hot water section consists of two
stacked soils, as shown in Figure 34.
When no factory piping or valve is included, the coil
connections are 1.625” ODM copper on 800 and 802C and
2.12" ODM copper on 047 and 077C. 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.
Figure 34. Hot water heat section (shown with factory valve
and piping)
Note:
The valve actuator spring returns to a stem up position
upon power failure. This allows full flow through the
coil.
Refer to the certified drawings for the recommended piping
entrance locations. Seal all piping penetrations to prevent air
and water leakage.
Note: Factory-installed water valves and piping are bronze,
brass, and copper. Dissimilar metals within the
plumbing system can cause galvanic corrosion. To avoid
corrosion, provide proper di-electric fittings as well as
appropriate water treatment.
Steam Coil Piping (All Units)
The steam heat section consists of two stacked coils pitched at
1/8" (3 mm) per foot (305 mm) as shown in Figure 35 to
provide positive condensate removal. When no factory piping
or valve is included, the coil connections are 2.5" male NPT
iron pipe.
Note: The valve actuator spring returns to a stem up position
upon power failure. This allows full flow through the
coil.
Figure 35. Steam heat section (shown with factory valve
and piping)
With the factory piping and valve package, the two coil
supplies are piped in parallel and controlled through a single
two-way valve. The field supply connection is of the same
female NPT size as the valve. Field return connections are
made at the 2.50" male NPT fittings on each of the two stacked
coils.
Refer to the sections on steam coil piping and trap
recommendations for additional information.
Note: The valve actuator spring returns to a stem up position
upon power failure. This allows full flow through the
coil.
Supply
Bypass
2.12 " ODM
Copper Coil
Connections
Upper
Coil
Air Flow
Lower
Coil
CAUTION
Coil freeze possible. Can damage equipment.
Follow instructions for mixing antifreeze solution used. Some
products have higher freezing points in their natural state than
when mixed with water. The freezing of coils is not the
responsibility of McQuay International. Refer to “Winterizing
Water Coils” on page 109.
Return
Lower
Coil
2.12 " ODM
Copper Coil
Connections
Upper
Coil
Supply
Return