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38 | reFrIGerAnT deSIGn
Single Zone Inverter W
all Mount Engineering Manual
Physical Pipe Length:
Actual length of straight segment(s) of pipe.
Equivalent Pipe Length:
Actual length of pipe plus equivalent
lengths of elbows and valves.
1. Draft a one-line diagram of the proposed piping system connect-
ing outdoor unit to indoor unit. Follow the pipe limitations listed.
2. Calculate the physical length of each pipe segment and note it on
the drawing.
3. Calculate the equivalent pipe length of each pipe segment.
using Elbows
Field-supplied elbows are
allowed as long as they are
designed for use with R410A
refrigerant. The designer,
however, should be cautious
with the quantity and size of fit-
tings used, and must account for
the additional pressure losses in
equivalent pipe length calcula-
tion. The equivalent pipe length
of each elbow must be added to
each pipe segment. See Table
11 for equivalent lengths.
Table 11:
Equivalent Piping Length for Piping Components
Field-provided isolation ball Valves
It is acceptable to install field-supplied ball valves with Schrader
ports at the indoor unit. Full-port isolation ball valves with Schrader
ports (positioned between valve and the indoor unit) rated for use
with R410A refrigerant should be used on both the liquid and vapor
lines.
If valves are not installed and the indoor unit needs to be removed or
repaired, the entire system must be shut down and evacuated.
Position valves with a minimum distance of three (3) to six (6) inches
of pipe on either side of the valve. Valves shall be easily accessible
for service. If necessary, install drywall access doors or removable
ceiling panels, and position the valves to face the access door or
ceiling panel opening. Mount valves with adequate space between
them to allow for placement of adequate pipe insulation around the
valves. Recommended best practice is to clearly label and docu-
ment locations of all service valves. The equivalent pipe length of
each ball valve must be added to each pipe segment.
Figure 15: Installing Piping Above and Below an obstacle
Above an obstacle.
3X
Below an obstacle.
Minimum
obstacles
When an obstacle, such as an I-beam or concrete T, is in the path
of the planned refrigerant pipe run, it is best practice to route the
pipe over the obstacle. If adequate space is not available to route
the insulated pipe over the obstacle, then route the pipe under the
obstacle. In either case, it is imperative the horizontal section of pipe
above or below the obstacle be a minimum of three (3) times greater
than the longest vertical rise (or fall) distance (Figure 15).
definitions
layout procedure
Refrigerant Piping System Layout
inStallation & layout bESt praCtiCES
Component
Size (Inches)
1/4 3/8 1/2 5/8 3/4
Elbow (ft.)
0.5 0.6 0.7 0.8 1.2
