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UNITS WITH FACTORY-INSTALLED HYDRONIC
PACKAGES — The 30RAP chillers with factory-installed
hydronic packages are designed for use with closed systems,
meaning that there is no more than one water-air interface in
the water loop. Cooling tower loops, for example, have two
water-air interfaces (sump and nozzles) and would thus be clas-
sified as open, whereas a correctly designed chilled water loop
with the only water-air interface being in the expansion tank is
closed. Since closed and open water systems behave very dif-
ferently, these instructions assume that the chilled water loop is
closed. A system installed incorrectly such that air is not han-
dled properly — pipe leaks, vent leaks, air in pipes, etc. — may
behave as an open system and thus have unsatisfactory opera-
tion. Pump seal wear can also cause leaks that cause poor sys-
tem operation.
Proper closed system design and installation procedures
should be followed closely. The system must be constructed
with pressure tight components and thoroughly tested for
installation leaks. Factory-supplied hydronic systems are avail-
able with single or dual (for back-up) pumps.
Figure 11 shows a typical installation with components that
might be installed with the hydronic package of the 30RAP
unit. The factory-installed system includes all of the compo-
nents within the dashed lines. Figure 12 illustrates a typical
dual pump package for the 010-030 size models.
NOTE: For units with single pumps, it is recommended that
isolation (shutoff) valves be placed exterior to the unit to
allow removal and service of the entire pump assembly, if
necessary. Units with dual pumps have pump isolation
valves provided. Also, if the unit is isolated with valves, a
properly sized pressure relief valve should be installed in
the piping between the unit and the valves, following all
applicable state and local codes.
System Pressurization
— A proper initial cold fill pressure
must be established before the filling of the unit. The initial
cold fill pressure is the pressure applied at the filling point to
fill a system to its highest point, plus a minimum pressure at the
top of the system (4 psi minimum) to operate air vents and pos-
itively pressurize the system.
The compression tank (sometimes called expansion tank) is
very important to system pressurization. The compression tank
actually serves several purposes:
1. Provide net positive suction head required (NPSHR) for
the pump to operate satisfactorily.
2. Set system pressure.
3. Accommodate expansion/contraction of water due to
temperature changes.
4. Acts as a pressure reference for the pump.
The compression tank pressure must be set BEFORE the
system is filled. The tanks are pre-charged at the factory to
40 psig (276 kPa). If the 30RAP unit with expansion tank is the
high point in the system, tank pre-charge pressure of 40 psig
(276 kPa) will be adequate. If the 30RAP unit with expansion
tank is NOT at the high point in the system, then the minimum
pre-charge pressure for the water system must be determined
using Table 2 and the method below:
Tank Pressure = 4 + (height from tank to top of
system in feet/“X”)
[27.6 + (height in m x 22.6/”X”)]
8
9
10
12
11
14
12
11
13
2
1
3
4
5
6
7
6
LEGEND
1—Strainer/Blow-Down Valve
2—Expansion Tank
3—Pump
4—Electric Heater
5—Air Vent Connection Port
6—Pressure/Temperature Access Port
7—Heat Exchanger
8— Flow Switch
9— Balance Valve/Drain Plug
10 — Pressure Relief
11 — Isolation Valves
12 — Flex Connections
13 — Pressure Reducing/Fill Valve
14 — Air Separator and Vent
--- Factory Supplied
a30-4871
Fig. 11 — Typical Piping Diagram — 30RAP Units with Hydronic Package