Carrier 42C Series Product Data page 15

Risers
Riser diameter is an important consideration in the design
of stack series systems. Standard units can accommodate
3 1
/ -in. to 2 / -in. riser sizes in 2-pipe systems. For other
4 2
applications, such as reverse return risers or 4-pipe sys-
tems, it may be necessary to accommodate the additional
risers.
Riser size is based on the water flow needed for a given
tier of units. Unit risers are sized according to the diameter
and length requirements as specified by the customer. To
determine riser size, water velocity should be limited to 5 to
8 ft/second. Thus, if 10 units are to be stacked vertically
with each unit requiring 3 gpm, the maximum flow in the
risers is 30 gpm. Through 1
of 7.5 ft/second. The maximum flow rate of 30 gpm
occurs only at the supply and return points. As the water
moves upward, the flow in the supply riser is reduced by
3 gpm per floor, so that after 3 floors, the total flow is
21 gpm and riser size can be reduced to one inch. See
chart on page 103.
42SH — EXPOSED CABINET
42SG — FURRED-IN STACK
1 / in. risers, this is a velocity
4
Condensate drains are available in sizes down to one
inch for greater first cost economy.
Riser size-reducers are factory installed and caps are pro-
vided at customer request.
For risers of over 115 in. length, filler pieces can be fur-
nished for field installation.
Typical arrangements
Typical arrangement applications for each model type are
shown below. The fan coil units feature almost an unlim-
ited number of arrangements to meet the needs of new
construction, renovation, or reconstruction. Consult the
factory for the arrangement (standard or special) to meet
your particular need.
42SJ — BACK-TO-BACK FURRED-IN STACK
42SG — FURRED-IN STACK MASTER/SLAVE UNIT
15