Trane RTAA-100, Installation & Maintenance Manual

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38 RTAA-SVX01A-EN
Installation — Remote Evaporator
Line Sizing
To determine the appropriate outside diameter for field installed liquid and
suction lines, it is first necessary to establish the equivalent length of pipe for
each line. It is also necessary to know the capacity (tons) of each circuit.
Circuit capacities for each RTAA unit are listed in
Table 2 .
Liquid Line Sizing Steps
Line sizing is an iterative process. While iterating to determine the proper
equivalent line length use the “Horizontal or Downflow” column of
Table 4 .
After the final equivalent line length has been determined in step # 9, then
break down the piping into it's “Horizontal or Downflow” and “Upflow”
components and select the proper outside diameter. Note that “Upflow” has
a column for one to five, six to ten, and eleven to fifteen feet.
The steps to compute liquid line size are as follows:
1. Compute the actual length of field installed piping.
2. Multiply the length from step # 1 by 1.5 to estimate the equivalent length.
3. Using Table 4 for the proper tonnage circuit, look in the “Horizontal or
Downflow” column. Find the outside diameter that corresponds to the
equivalent length computed in step # 2.
4. With the outside diameter found in step # 3, use Table 3 to determine the
equivalent lengths of each fitting in the field installed piping.
5. Sum the equivalent lengths of all the field installed elbows.
6. Add the length found in step # 5 to the actual length from step # 1. This is
your new equivalent line length.
7. Using Table 4 again, find the new outside diameter that corresponds to
the new equivalent line length from step # 6.
8. Using Table 2b and the new outside diameter found in step # 7, find the
equivalent line length of each elbow, and sum them.
9. Add the length found in step # 8 to the actual length from step # 1. This is
your final equivalent line length.
10. With the final equivalent line length found in step # 9, use Table 4 to
select the proper outside diameter for horizontal or downflow lines, and
any upflow lines.