Installation manual

McQuay IM 487-4 33
Introduction
Figure 36. Two-way valve package
Steam Piping Recommendations
1 Be certain that adequate piping flexibility is provided.
Stresses resulting from expansion of closely coupled piping
and coil arrangement can cause serious damage.
2 Do not reduce pipe size at the coil return connection. Carry
return connection size through the dirt pocket, making the
reduction at the branch leading to the trap.
3 Install vacuum breakers on all applications to prevent
retaining condensate in the coil. Generally, the vacuum
breaker is to be connected between the coil inlet and the
return main. However, if the system has a flooded return
main, the vacuum breaker to the atmosphere; the trap
design should allow venting of the large quantities of air.
4 Do not drain steam mains or takeoffs through coils. Drain
mains ahead of coils through a steam trap to the return line.
5 Do not attempt to lift condensate when using modulating or
on-off control.
6 Pitch all supply and return steam piping down a minimum
of 1" (25 mm) per 10 feet (3 m) of direction of flow.
Steam Trap Recommendations
1 Size traps in accordance with manufacturers’
recommendations. Be certain that the required pressure
differential will always be available. Do not undersize.
2 Float and thermostatic or bucket traps are recommended for
low pressure steam. Use bucket traps on systems with on-
off control only.
3 Locate traps at least 12" (305 mm) below the coil return
connection.
4 Always install strainers as close as possible to the inlet side
of the trap.
5 A single tap may generally be used for coils piped in
parallel, but an individual trap for each coil is preferred.
Figure 37. Heating coil piping with vestibule
R e t u r n
S u p p l y