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14
ENG
Heos BOX R704
+0300140EN - rel. 1.0 - 25.05.2022
2.12 Requirements for positioning the
unit and multi-evaporator layout
The section of the refrigerant circuit connecting the Heos Box R744 and
the unit must be designed to avoid oil retention, which could prevent
oil from returning to the compressor and consequent reliability and
operating problems. Oil return depends on several factors, the main ones
being the diameter of the piping (speed), the compressor variable rotation
speed (refrigerant flow-rate = speed) and the piping layout path (up/down
sections, couplings, manifolds, etc.) and therefore the best piping diameter
must be an acceptable compromise based on the range of unit operating
speeds. The following paragraphs show the piping design specifications
to ensure the correct circulation of oil inside the refrigerant circuit. The
reference cooling capacities for the various operating conditions shown
in the tables have been calculated considering the pipe thicknesses shows
in the table below).
Description Piping nominal outside diameter (OD), mm
OD (mm) 6 8 10 12 14 16 18 22
w (mm) 0.8 0.8 1 1 1 1.1 1.2 1.5
2.12.1 Piping layout in multi-evaporator configu-
ration
Heosbox cannot serve more than three evaporators. A multisplit layout
is required (each evaporator with its own suction line running to the
Box). The manifold, located near the Box, must be designed to prevent
accumulation of oil. This layout ensures correct speeds in the piping and a
good balance between pressure drop and oil return. Another acceptable
configuration involves a common liquid line (NB: the last evaporator also
needs to be well supplied with liquid) and the suction lines in a multisplit
arrangement. Multiplex configurations (common suction line) are not
allowed. Furthermore, the Box should be installed in a central position with
reference to the evaporators, so as to not be unbalanced on one side of
the system.
Multisplit
showcase A
showcase B
showcase C
Heosbo
x
Fig. 2.k
Common liquid line
showcase A showcase B showcase C
Heosbo
x
Fig. 2.l
Multiplex: configuration not permitted
showcase A showcase B showcase C
Heosbo
x
Fig. 2.m
Key
Suction
Liquid
The suction pipe manifold must be designed to prevent accumulation
of oil. The suggested shapes and dimensions of the manifold are shown
below.
compr
essor
e
banco frigo
collettore
banco frigo
banco frigo
1
2
3
Fig. 2.n
Model
HB200C0300CE0 HB200C0400CE0 HB200C0600CE0 HB200C1000CE0
Heos Box suction line
Outside
diameter
10 mm
Outside
diam-
eter 10
mm
Outside
diameter
12 mm
Outside
diameter
12 mm
Suction manifold
Outside
diameter
12 mm
Outside
diam-
eter 12
mm
Outside
diameter
16 mm
Outside
diameter
16 mm
Tab. 2.l
Caution: the thickness of the copper piping should be suitable for
the PS of the final assembly (comprising Heos Box and the evaporator
system)
Notice:
when designing the system (multi-split layout or common
liquid line) and during operation, the following are recommended:
• Place ball valves near the suction manifolds or on the liquid lines to
prevent the formation of “dead-end branches” in the system. These must
be avoided, as oil will accumulate there whenever a showcase is not
working. For this reason, a showcase should never be out of service for
more than 48 hours.