Zehnder Rittling HP Series Installation and operating instructions

i
Installation, Operation and Maintenance
Horizontal
Heat Pump
Hydronic Heating Fan Coils Radiant ceiling systems Water Source Heat Pumps

Table of Contents
Model nomenclature 1
General information 2
General data 4
Horizontal installation 7
Piping installation 12
Water loop applications 13
Ground loop applications 14
Ground water applications 15
Water quality standards 17
Electrical: line voltage 18
Electrical: low voltage wiring 19
Electrical: power wiring 19
Blower performance data 20
Wiring diagrams 21
Microprocessor control system 27
Dip switch settings and operation 28
Standard 24VAC sequence of operation 29
Communicating thermostat 30
Unit starting and operating conditions 33
Piping system cleaning and flushing 34
Unit and system checkout 35
Unit start-up procedure 36
Preventive maintenance 38
Troubleshooting 40
Lockout modes 41
Start-up log 42
Troubleshooting worksheet 43
Warranty 44
IMPORTANT: Submittal documentation, specific to
each project, supersedes the general guidelines
contained within this manual.

1Nomenclature
Unit type
HP = Heat Pump
Model
S = Single State
Cabinet configuration
H = Horizontal
V = Vertical
Nominal capacity
009 = 9,000 BTU/Hr
012 = 12,000 BTU/Hr
015 = 15,000 BTU/Hr
018 = 18,000 BTU/Hr
024 = 24,000 BTU/Hr
030 = 30,000 BTU/Hr
036 = 36,000 BTU/Hr
042 = 42,000 BTU/Hr
052 = 52,000 BTU/Hr
062 = 62,000 BTU/Hr
072 = 72,000 BTU/Hr
Voltage
A = 208-230V/60/1
B = 277V/60/1
C = 208-230V/60/3
D = 460V/60/3
Blower/motor options
A = Standard/PSC
B = High static/PSC
C = Standard/ECM
D = High static/ECM
Heat exchanger
1 = Copper coax/coated air coil
1, 2 3 4 5, 6, 7 8 9 10 11 12 13 14 15, 16 17 18 19, 20
HP S H 009 A A 1 X X S 1 EL A – AA
Nomenclature
HP series
Special option codes
AA = Standard
Placeholder
Revision level
A = Rev. 1
Supply air/return air configuration
EL = End/left (horizontal only)
ER = End/right (horizontal only)
SL = Side/left (horizontal only)
SR = Side/right (horizontal only)
TL = Top/left (vertical upflow only)
TR = Top/right (vertical upflow only)
LR = Left/right (vertical upflow only)
RL = Right/left (vertical upflow only)
BL = Bottom/left (vertical downflow only)
BR = Bottom/right (vertical downflow only)
Power termination
X = No disconnect
1 = Disconnect switch
Controls
S = Microprocessor controls
C = Microprocessor and customer supplied DDC controls
L = Microprocessor and Lon Network communication
B = Microprocessor and BACnet network communication
Options
X = None (standard)
Hot gas bypass/reheat
X = None

General
information
Inspection: Upon receipt of
the equipment, carefully check
the shipment against the bill
of lading. Make sure all units
have been received. Inspect
the packaging of each unit and
inspect each unit for damage.
Ensure that the carrier makes
proper notation of any shortages
or damage on all copies of
the freight bill and completes
a common carrier inspection
report. Concealed damage not
discovered during unloading
must be reported to the carrier
within 15 days of receipt of
shipment. If not filed within 15
days, the freight company can
deny the claim without recourse.
Note: It is the responsibility
of the purchaser to file all
necessary claims with the
carrier.
Storage: Equipment should be
stored in its original packaging in
a clean, dry area. Store units in an
upright position at all times. Stack
units a maximum of 3 units high.
Unit protection: Cover units
on the job site with either
the original packaging or an
equivalent protective covering.
Cap the open ends of pipes
stored on the job site. In areas
where painting, plastering,
and/or spraying has not been
completed, all due precautions
must be taken to avoid
physical damage to the units
and contamination by foreign
material. Physical damage and
contamination may prevent
proper start-up and may result in
costly equipment clean-up.
Examine all pipes, fittings, and
valves before installing any of the
system components. Remove
any dirt or debris found in or on
these components.
To avoid the release of
refrigerant into the atmosphere,
the refrigerant circuit of this
unit must be serviced only by
properly trained technicians who
meet local, state, and federal
requirements.
To avoid equipment damage,
do not use these units as a
source of heating or cooling
during the construction process.
The mechanical components
and filters will quickly become
clogged with construction dirt
and debris, which may cause
system damage and/or void the
warranty.
The installation of water
source heat pumps and all
associated components, parts,
and accessories which make
up the installation shall be in
accordance with the regulations
of all authorities having
jurisdiction and must conform
to all applicable codes. It is the
responsibility of the installing
contractor to determine and
comply with all applicable codes
and regulations.
All refrigerant discharged from
this unit must be recovered.
Technicians must follow industry
accepted guidelines and all local,
state, and federal statutes for
the recovery and disposal of
refrigerants. If the compressor
is removed, oil will remain in
the compressor. To avoid oil
leakage, compressor suction and
discharge lines must be sealed
after it is removed.
Warnings, cautions, and notices
appear throughout this manual.
Read these items carefully before
attempting installation, service, or
troubleshooting of the equipment.
Indicates an immediate hazardous
situation, which if not avoided will
result in death or serious injury.
Danger labels on unit access
panels must be observed.
Indicates a potentially hazardous
situation, which if not avoided could
result in death or serious injury.
Indicates a potentially hazardous
situation or an unsafe practice, which
if not avoided could result in minor
or moderate injury or product or
property damage.
Notification of installation, operation,
or maintenance information, which is
important, but is not hazard-related.
2

General
information
Pre-installation: Installation,
operation and maintenance
instructions are provided with
each pallet. Horizontal equipment
is designed for installation
above false ceiling or in a ceiling
plenum. The installation site
chosen should include adequate
service clearance around the
unit. Before unit start-up, read
all manuals and become familiar
with the unit and its operation.
Thoroughly check the system
before operation.
Prepare units for installation
as follows:
 Compare the data on the unit
nameplate with ordering and
shipping information to verify
that the correct unit has been
received.
 Keep the cabinet covered with
the original packaging until
installation is complete and
all plastering, painting, etc. is
finished.
 Verify refrigerant tubing is
free of kinks or dents and that
it does not touch other unit
components.
 Inspect all electrical
connections. Connections
must be clean and tight at the
terminals.
 Remove blower shipping
support packaging, if
applicable.
 Some airflow patterns are field
convertible. Locate the airflow
conversion section of this
manual for instructions.
All three phase scroll
compressors must have direction
of rotation verified at start-
up. Verification is achieved by
checking compressor amp draw.
Amp draw will be substantially
lower compared to nameplate
values if wired incorrectly.
Additionally, reverse rotation
results in an elevated sound level
compared to correct rotation.
Reverse rotation will result in
compressor internal overload
trip within several minutes.
Verify compressor type before
proceeding.
Do not store or install units in
corrosive environments or in
locations subject to temperature
or humidity extremes (e.g.,
attics, garages, rooftops, etc.).
Corrosive conditions and high
temperature or humidity can
significantly reduce performance,
reliability, and service life. Always
move and store units in an
upright position. Tilting units on
their sides may cause equipment
damage.
Cut hazard: Failure to follow
this caution may result in
personal injury. Sheet metal
parts may have sharp edges
or burrs. Use care and wear
appropriate protective clothing,
safety glasses and gloves when
handling parts and servicing heat
pumps.
3General information

English units
Size 009 012 015 018 024 030 036 042 052 062 072
Compressor and refrigerant data
Compressor
(1 each) Rotary Rotary Rotary Rotary Scroll Scroll Scroll Scroll Scroll Scroll Scroll
Refrigerant charge
R410A (oz) 38.9 40.6 48.8 51.2 65.4 76 86.6 91.9 121.9 127.2 141.3
Motor and blower data
Blower wheel size
(D x W) (in.) 7×7 7×7 7×7 7×7 9x6 9x6 9×9 9×9 10×10 10×10 10×10
PSC fan motor
power (HP) 1/12 1/12 1/6 1/6 1/4 1/4 3/5 3/5 3/4 3/4 3/4
ECM fan motor
power (HP) 1/4 1/4 1/4 1/4 1/4 1/4 3/4 3/4 3/4 3/4 3/4
Fluid and electrical connection data
Water connection
size (FPT) 1/2" 1/2" 3/4" 3/4" 1" 1" 1" 1" 1" 1" 1"
Condensate
connection size
OD (in.)
7/8" 7/8" 7/8" 7/8" 7/8" 7/8" 7/8" 7/8" 7/8" 7/8" 7/8"
Electrical
knockouts (in.) 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1" 2 x 1"
Air coil data
Total face area (ft²) 1.84 1.84 2.66 2.66 3.76 3.76 4.92 4.92 6.29 6.29 6.29
Tube size (in.) 3/8" 3/8" 3/8" 3/8" 3/8" 3/8" 3/8" 3/8" 3/8" 3/8" 3/8"
Fin spacing (FPI) 14 14 14 14 14 14 14 14 14 14 14
Number of rows 3 3 3 3 3 3 3 3 3 3 3
Dimensional and mass data
Cabinet length (in.) 43 3/8 43 3/8 51 1/4 51 1/4 61 61 67 1/4 67 1/4 81 1/8 81 1/8 81 1/8
Cabinet height (in.) 17 3/8 17 3/8 19 1/4 19 1/4 20 1/2 20 1/2 21 1/4 21 1/4 21 1/4 21 1/4 21 1/4
Cabinet width (in.) 22 1/8 22 1/8 22 1/8 22 1/8 23 5/8 23 5/8 25 3/4 25 3/4 25 3/4 25 3/4 25 3/4
Standard 1"
disposable filter
(in.)
19.25×16 19.25×16 24.5×17.75 24.5×17.75
1@
19.25×16
1@
19.25×16.5
1@
19.25×16
1@
19.25×16.5
14.25×20
24×20"
14.25×20
24×20
2 @
24×20
2 @
24×20
2 @
24×20
Shipping weight
(lbs.) 165 175 208 220 305 320 340 356 449 462 474
Unit physical data
4

Metric (S.I.) units
Size 009 012 015 018 024 030 036 042 052 062 072
Compressor and refrigerant data
Compressor
(1 each) Rotary Rotary Rotary Rotary Scroll Scroll Scroll Scroll Scroll Scroll Scroll
Factory refrigerant
charge R410A (kg) 1.10 1.15 1.38 1.45 1.86 2.16 2.46 2.61 3.46 3.61 4.01
Motor and blower data
Blower wheel size
(D x W) (cm) 17.8x17.8 17.8x17.8 17.8x17.8 17.8x17.8 22.9x15.2 22.9x15.2 22.9x22.9 22.9x22.9 25.4x25.4 25.4x25.4 25.4x25.4
PSC fan motor
power (W) 60 60 120 120 180 180 450 450 550 550 550
ECM fan motor
power (W) 185 185 185 185 185 185 560 560 560 560 560
Fluid and electrical connection data
Water connection
size (FPT) 1/2" 1/2" 3/4" 3/4" 1" 1" 1" 1" 1" 1" 1"
Condensate
connection size
OD (mm)
22 22 22 22 22 22 22 22 22 22 22
Electrical
knockouts (mm) 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25 2 x 25
Air coil data
Total face area (m²) 0.17 0.17 0.25 0.25 0.35 0.35 0.46 0.46 0.58 0.58 0.58
Tube size (mm) 9.52 9.52 9.52 9.52 9.52 9.52 9.52 9.52 9.52 9.52 9.52
Fin spacing (fins/cm) 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5
Number of rows 3 3 3 3 3 3 3 3 3 3 3
Dimensional and mass data
Cabinet length (cm) 110.2 110.2 130.2 130.2 154.9 154.9 170.8 170.8 206.1 206.1 206.1
Cabinet height (cm) 44.1 44.1 48.9 48.9 52.1 52.1 54.0 54.0 54.0 54.0 54.0
Cabinet width (cm) 56.2 56.2 56.2 56.2 60.0 60.0 65.4 65.4 65.4 65.4 65.4
Standard 1"
disposable filter
(mm)
48.9x40.6 48.9x40.6 62.2x45.1 62.2x45.1
1@
48.9x40.6
1@
48.9x41.9
1@
48.9x40.6
1@
48.9x41.9
1@
36.2x50.8
1@
61.0x50.8
1@
36.2x50.8
1@
61.0x50.8
2@
61.0x50.8
2@
61.0x50.8
2@
61.0x50.8
Shipping weight
(kgs) 74.9 79.5 94.4 99.9 138.5 145.3 154.4 161.6 203.8 209.7 215.2
Unit physical data
5General information

Dimensions and data
Front
7/8" (2.2) OD
condensate
Compressor
access panel
Left return
Side
discharge
End
discharge
Front
7/8" (2.2) OD
condensate
Compressor access panel
Right return
End
discharge
Side
discharge
E
F
D D
E
F
Front view
Power
supply
Low voltage knockout
Loop out
Loop in
Control box
access panel
Or Or
Left return
C
J H G
K
Blower outlet
Front
Compressor access panel
Blower
access
panel
Side discharge view
0.9" (2.3)
2.4" (6.1)
B
A
J
M
K
L 3.0" (7.6)
End discharge view
Blower
outlet
R
P
N
S
Air coil return
Compressor access panel
Front
Air coil view
Right return
C
J H
M
K
Blower outlet
Front
Compressor
access panel
Blower
access
panel
Compressor
access panel
Air coil
return
Side discharge view
A
B
2.4" (6.1)
0.9" (2.3)
G
K
J L 3.0" (7.6)
Blower
outlet
End discharge view
R
P
N
S
Front
Air coil view
Top view
T
U
W
0.9" (2.3) 1.0" (2.5)
Top view
(Units 1 to 8)
Front
T
U
3.7" (9.4)
1.0" (2.5) 1.0" (2.5)
Front
Top view
(Units 9, 0, A)
Model
Overall cabinet Water and electrical
connections
Discharge connection
integral duct flange
Return connection filter
rack duct flange Hanger locations
A
Width
B
Height
C
Length D E F
Loop in/
loop out
NPT
G H J
Width
K
Height L M N P R Width
S
Height T U W
009, 012 22.1" 17.3" 43.3"
1.8"
4.5" 12.9" 1/2" 2.2" 5.3" 9.3" 8.4" 6.3" 6.8" 1.3" 2.9" 16.9" 15.2" 20.1" 43.6" 24.5"
015, 018 19.3" 51.2" 5.0" 11.0" 3/4" 3.2" 7.7 " 1.2" 2.6" 22.4" 16.9" 51.4"
024, 030 23.4" 20.5" 60.8" 4.5" 16.0"
1"
3.3" 12.3" 11.9" 8.8" 5.8" 8.4" 1.3"
3.0"
30.5" 18.3" 21.7" 61.3" 26.0"
036
25.8" 21.3"
6 7. 2"
5.1" 17. 2 "
4.1" 12.9" 12.1" 10.6" 6.7" 6.6"
1.5"
35.8" 24.1" 6 7.7 " 28.3"
042
18.9"
052,
062, 072 81.0" 1.8" 15.0" 13.3" 11.8" 6.1" 7.7" 45.7" 23.8" 86" N/A
6

Horizontal
installation
Horizontal unit location
Units are not designed for
outdoor installation. Locate
the unit in an indoor area that
allows enough space for service
personnel to perform typical
maintenance or repairs without
removing unit from the ceiling.
Horizontal units are typically
installed above a false ceiling or
in a ceiling plenum. Never install
units in areas subject to freezing
or where humidity levels could
cause cabinet condensation
(such as unconditioned spaces
subject to 100% outside air).
Consideration should be given to
access for easy removal of the
filter and service access panels.
Provide sufficient room to make
water, electrical, and duct
connections.
If the unit is located in a confined
space, provisions must be
made for return air to freely
enter the space by means of a
louvered door, etc. Any access
panel screws that would be
difficult to remove after the unit
is installed should be removed
prior to setting the unit. Refer to
Figure 4 for an illustration of a
typical installation. Refer to unit
submittal data or engineering
design guide for dimensional
data.
The installation of water
source heat pump units and all
associated components, parts
and accessories which make
up the installation shall be in
accordance with the regulations
of all authorities having
jurisdiction and must conform
to all applicable codes. It is the
responsibility of the installing
contractor to determine and
comply with all applicable codes
and regulations.
Follow these guidelines when
selecting unit location:
 Provide a hinged access door
in concealed-spline or plaster
ceilings. Provide removable
ceiling tiles in T-bar or lay-in
ceilings. Refer to horizontal
unit dimensions for specific
series and model in unit
submittal data.
 Size the access opening to
accommodate the service
technician during the removal
or replacement of the
compressor and the removal
or installation of the unit itself.
Zehnder Rittling recommends
at least 24" clearance around
all service access panels
 Provide access to hanger
brackets, water valves and
fittings. Provide screwdriver
clearance to access panels,
discharge collars and all
electrical connections.
 Provide access for filter
service. Filter access doors
are located at both ends of the
filter track.
 Do not obstruct the space
beneath the unit with piping,
electrical cables and other
items that prohibit future
removal of components or the
unit itself.
 Use a manual portable jack/lift
to lift and support the weight
of the unit during installation
and servicing.
Horizontal installation 7

Horizontal
installation
Mounting horizontal units
Horizontal units, sizes 009-042,
have hanger brackets pre-
installed from the factory as
shown in Figure 1. Larger units
(sizes 052-072) utilize factory-
installed U-channel support rails
for hanging installation.
See Figure 2.
Horizontal Heat Pumps are
typically suspended above a
ceiling or within a soffit using
field supplied, threaded rods
sized to support the weight of
the unit.
Use four (4) field supplied
threaded rods and field or factory
provided vibration isolators to
suspend the unit. Hang the unit
clear of the floor slab above
and support the unit by the
mounting bracket/U-channel rail
assemblies only. Do not attach
the unit flush with the floor slab
above.
Pitch the unit toward the drain
as shown in Figure 3 to improve
condensate drainage. Ensure
that unit pitch does not cause
condensate leaks inside the
cabinet.
Air coil: To obtain maximum
performance, the air coil should
be cleaned before start-up. A
10% solution of dishwasher
detergent and water is
recommended for both sides of
the coil. A thorough water rinse
should follow.
Installation note, ducted
return: Many horizontal heat
pumps are installed in a return air
ceiling plenum application (above
ceiling). A filter track is included
on Zehnder Rittling Heat Pumps
for the purposes of holding the
filter and providing a flange
for duct connection. Canvas
or flexible connectors should
be used to minimize vibration
between the unit and ductwork.
 It is not possible to field convert return air
between left or right return models due to
the necessity of refrigeration copper piping
changes.
Figure 1: Hanger brackets, sizes 009-042
Figure 2: U-channels, sizes 052-072
Figure 4: Typical horizontal unit installation
Figure 3: Unit pitch for improved
condensate drainage
Vibration
isolator
(factory
supplied)
Washer
(by others)
Double hex nuts
(by others)
3/8" (10 mm)
Threaded rod
(by others)
Vibration isolator
(factory supplied)
Washer
(by others)
Double hex nuts
(by others)
3/8" (10 mm)
Threaded rod
(by others)
Return air
Thermostat wiring
Flex hose
In
Out
Isolation mounts
Duct flange
Supply
air
Unit power
(disconnect by others)
3/8" (10 mm) threaded rods
(4 places) (by others)
Water
connections
Drain pan condensate connection
1/8"/ft. (10 mm/m)
downward pitch
for condensate
drainage
8

End Discharge
Water connection end
Return air
Supply duct
Water connection end
Return air
Side Discharge
Supply duct
Remove
3 screws Remove screw
Remove
2 screws
Water
connection end
Return air
Side Discharge
Rotate 180° and
move to end
Move to side
Water
connection end
Return air
Replace screw
Replace 3 screws
Replace
2 screws
Water connection end
Return air
End Discharge
Conversion
Figure 5: Left return side to back
Horizontal
installation
Field conversion of
air discharge
Overview: Horizontal units can
be field converted between
side (straight) and end (back)
discharge using the instructions
below.
Preparation: It is best to field
convert the unit on the ground
before hanging. If the unit is
already hung it should be taken
down for field conversion.
Side-to-end discharge
conversion:
 Place unit in well lit area.
Remove the screws as shown
in Figure 5 to free service
access and discharge panels.
 Remove blower motor service
access panel and set aside
(side or end).
 Unplug blower motor at quick
disconnect.
 Lift and rotate the discharge
panel to the desired position.
The supply air duct height will
change slightly to allow blower/
motor serviceability.
 Reconnect blower motor at
quick disconnect.
 Check blower wiring and
connections for tension or
contact with sheet metal
edges. Re-route and secure
if necessary.
 Manually spin the fan wheel
to ensure that the wheel is not
rubbing or obstructed.
Figure 6: Right return side to back
 Reinstall service access panel.
 Reinstall screws (note: the
location for some screws will
have changed).
 Conversion should resemble
Figure 5 or Figure 6 for left or
right return, respectively.
End-to-side discharge
conversion: If the discharge is
changed from end to side, use
above instruction noting that
illustrations will be reversed.
Left vs. right return: It is not
possible to field convert return
air between left and right return.
However, the conversion process
of side to end or end to side
discharge for either right or left
return configuration is the same.
Horizontal Installation 9

Horizontal
installation
Condensate piping
A condensate drain line must
be installed and pitched away
from the unit to allow for proper
drainage. This connection must
meet all local plumbing/building
codes.
Zehnder Rittling condensate
connections are stainless steel.
Soldering or brazing of fittings
is difficult and mechanical
connection methods are
recommended. Condensate
piping should be isolated from
the unit through the use of a soft
connection to avoid transmission
of noise and vibration.
Pitch the unit toward the drain
as shown in Figure 3 (page 8) to
improve condensate drainage.
Ensure that unit pitch does not
cause condensate leaks inside
the cabinet. Install a condensate
trap at each unit with the top of
the trap positioned below the
unit condensate drain connection
as shown in Figure 7. Design
the depth of the trap (water-
seal) based upon the amount of
ESP capability of the blower. In
general, 1-1/2 inch (38mm) trap
depth is the minimum. Each unit
must be installed with its own
individual trap and connection
to the condensate line (main) or
riser.
Provide a means to flush or blow
out the condensate line. Do not
install units with a common trap
and/or vent.
Always vent the condensate line
when dirt or air can collect in
the line or a long horizontal drain
line is required. Also vent when
large units are working against
higher external static pressure
than other units connected to
the same condensate main since
this may cause poor drainage
for all units on the line. When a
vent is installed in the drain
line, it must be located after
the trap in the direction of the
condensate flow.
Ensure condensate line is
pitched toward drain 1/4" per ft
(21 mm per m) of run.
Figure 7: Horizontal condensate connection
1-1/2" (38 mm)
Vent (by others)
3/4" copper or
PVC
construction
(by others)
Soft connection to
unit condensate
nipple
1/4"/ft.
(21 mm/m)
of drainage slope
1-1/2" (38 mm)
minimum
10

Horizontal
installation
Duct system installation
Proper duct sizing and design
is critical to the performance of
the unit. The duct system should
be designed to allow adequate
and even airflow through the unit
during operation. Air flow through
the unit must be at or above
the minimum stated airflow for
the unit to avoid equipment
damage and/or nuisance system
error codes. Duct systems
should be designed for quiet
operation. A flexible connector
is recommended for both
discharge and return air duct
connections on metal duct
systems to eliminate the transfer
of vibration to the duct system.
To maximize sound attenuation
of the unit blower, the supply
and return plenums should
include internal duct liner or be
constructed from ductboard for
the first few feet. Application of
the unit to uninsulated ductwork
in an unconditioned space is
not recommended, as the unit’s
performance may be adversely
affected.
At least one 90° elbow should
be included in the supply duct to
reduce air noise.
If the unit is connected to
existing ductwork, a previous
check should have been made
to ensure that the ductwork has
the capacity to handle the airflow
required for the unit. If ducting is
too small, as in the replacement
of a heating only system, larger
ductwork should be installed.
All existing ductwork should be
checked for leaks and repaired
as necessary.
Note
 Refer to Figure 3 on page 8 for horizontal
duct system details.
Horizontal Installation
Flex hose
Return air
Return air
Supply air
Locate unit over hallways
where possible
Insulated return
(optional)
Flexible duct collar
90° elbow
Flexible duct
connection
Insulated
supply
Figure 8: Typical duct system
11

Piping
installation
Installation of supply and
return piping
Follow these piping guidelines:
 Install a drain valve at the base
of each supply and return riser
to facilitate system flushing.
 Install shut-off/balancing
valves and unions at each
unit to permit unit removal for
servicing.
 Place strainers at the inlet of
each system circulating pump.
 Select the proper hose length
to ensure slack between
connection points.
 Do not exceed the minimum
bend radius for the hose
selected (refer to Table 1).
Tighter bends may cause the
hose to collapse resulting in
reduced water flow.
Table 1: Metal hose
minimum bend radii
Hose
diameter
Minimum bend
radius
1/2" (12.7 mm) 2-1/2" (6.4 cm)
3/4" (19.1 mm) 4" (10.2 cm)
1" (25.4 mm) 5-1/2" (14 cm)
Insulation is not required on loop
water piping except where the
piping runs through unheated
areas, outside the building or
when the loop water temperature
is below the minimum expected
dew point of the pipe ambient
conditions. (Insulation is required
for ground loop applications in
most climates.)
Pipe joint compound is not
necessary when Teflon®thread
tape is pre-applied to hose
assemblies or when flared-end
connections are used. If pipe
joint compound is preferred, use
compound only in small amounts
on the external pipe threads of
the fitting adapters (never on
the threads of the flare side of
a fitting). Prevent sealant from
reaching the flared surfaces of
the joint.
Maximum allowable torque for
brass fittings is 30 ft-lbs (41
N-m). If a torque wrench is not
available, tighten finger-tight plus
one quarter turn. Tighten steel
fittings as necessary.
Optional pressure-rated hose
assemblies are available for
use with Zehnder Rittling units.
Similar hoses can be obtained
from alternate suppliers. Supply
and return hoses are fitted
with swivel-joint fittings at one
end to prevent kinking during
installation. (Refer to Figure 9.)
Install hose assemblies properly
and check regularly to avoid
system failure and reduced
service life.
Corrosive system water requires
corrosion resistant fittings and
hoses, and may require water
treatment.
Do not bend or kink supply lines
or hoses.
Piping must comply with all
applicable codes.
Do not allow hoses to rest
against structural building
components. Compressor
vibration may be transmitted
through the hoses to the
structure, causing unnecessary
noise complaints.
Figure 9: Typical horizontal unit installation
Note
 When antifreeze is used in the loop, ensure
that it is compatible with the Teflon®tape or
pipe joint compound that is applied.
Overall length
(without adaptor)
37° female JIC
swivel crimp on fitting
UL-94VO fire-rated
thermoplastic inner
tube
bonded to
stainless steel
outer braid
Rigid male pipe
NPTF with
dryseal applied
crimp on fitting
37° male JIC x male pipe thread
NPTF with dryseal applied
12

Commercial water loop
Commercial systems typically
include a number of units
connected to a common piping
system. Any unit plumbing
maintenance work can
introduce air into the piping
system; therefore air elimination
equipment is a major component
of the mechanical room
plumbing. Consideration should
be given to insulating the piping
surfaces to avoid condensation.
Zehnder Rittling recommends
unit insulation any time the water
temperature is expected to be
below 60 ºF (15.6 ºC). Metal-to-
plastic threaded joints should
never be used due to their
tendency to leak over time.
Piping installation
Teflon®tape thread sealant
is recommended to minimize
internal fouling of the heat
exchanger. Do not over tighten
connections and route piping so
as not to interfere with service
or maintenance access. Hose
kits are available from Zehnder
Rittling in different configurations
as shown in Figure 10 for
connection between the unit
and the piping system. Depending
upon selection, hose kits may
include shut-off valves, P/T plugs
for performance measurement, high
pressure stainless steel braided
hose, “Y” type strainer with blow
down valve, balancing valve, and/or
“J” type swivel connection. Balancing
valves and an external low pressure
drop solenoid valve for use in
variable speed pumping systems may
also be included in the hose kit.
The piping system should be
flushed to remove dirt, piping chips,
and other foreign material prior
to operation (see “Piping System
Cleaning and Flushing Procedures”
in this manual). The flow rate is
usually set between 2.25 and 3.5
gpm per ton (2.9 and 4.5 l/m per kW)
of cooling capacity. Zehnder Rittling
recommends 3.3 gpm per ton (4.3
l/m per kW) for most applications of
water loop heat pumps. To ensure
proper maintenance and servicing,
P/T ports are imperative for
temperature and flow verification, as
well as performance checks.
Loop conditions
Water loop heat pump (cooling
tower/boiler) systems typically
utilize a common loop, maintained
Note
 Refer to page 11 for horizontal duct
system details.
 Note: Low water temperature operation
requires extended range equipment.
Figure 10: Typical water loop application
Applications
Return air
Supply air
Flex hose
Out
In
Building loop
Ball valve with PT port
Control valve
Flow regulator
Water loop applications
between 60-90 °F (16-32 °C).
The use of a closed circuit
evaporative cooling tower with
a secondary heat exchanger
between the tower and the
water loop is recommended. If an
open type cooling tower is used
continuously, chemical treatment
and filtering will be necessary. For
low entering water temperature
applications, Zehnder Rittling
recommends following the water
limit guidelines:
Table 2:
Water limit guidelines
EWT
min.
(°F)
Min. flow
rate
(GPM/ton)
Antifreeze
required?
50 1.5 No
40-50 3No
40-50 1.5 Yes
20-40 3Yes
Low water temperature
cutout setting
Zehnder Rittling’s heat pump
controller includes a user
configurable switch (DIP switch 2
on the PCB controller) to change
the low water temperature cutout
(FP1) setting between water
(30 °F) and Glycol (10 °F). When
loop conditions allow (antifreeze is
used), the FP1 DIP switch should
be set to the Glycol (10 °F) setting
to avoid nuisance faults.
13

The following instructions
represent industry accepted
installation practices for closed
loop, earth coupled heat pump
systems. Instructions are
provided to assist the contractor
in installing trouble free ground
loops. These instructions are
recommendations only. State/
provincial and local codes must
be followed and installation must
conform to all applicable codes.
It is the responsibility of the
installing contractor to determine
and comply with all applicable
codes and regulations.
Ground loop applications require
extended range equipment and
optional refrigerant/water circuit
insulation.
Piping installation
All earth loop piping materials
should be limited to polyethylene
fusion only for in-ground
sections of the loop. Galvanized
or steel fittings should not be
used at any time due to their
tendency to corrode. All plastic
to metal threaded fittings
should be avoided due to their
potential to leak in earth coupled
applications. A flanged fitting
should be substituted. P/T plugs
should be used so that flow can
be measured using the pressure
drop of the unit heat exchanger.
Earth loop temperatures can
range between 25 and 110 °F
(-4 to 43 °C). Flow rates between
2.25 and 3 gpm (2.41 to 3.23
l/m per kW) of cooling capacity
are recommended in these
applications.
Pressure test water loop piping prior
to unit installation. Pressures of at
least 100 psig (689 kPa) should be
used when testing. Do not exceed
the pipe pressure rating. Test entire
system when all loops are assembled.
Upon completion of system
installation and testing, flush the
system to remove all foreign objects
and purge to remove all air.
Loop conditions
When entering loop conditions
meet values specified in Table 3
below or where piping will be routed
through areas subject to freezing,
antifreeze is required. Alcohols
and glycols are commonly used as
antifreeze; however your local sales
representative should be consulted
to determine the antifreeze best
suited to your area. Freeze protection
should be maintained to 15 °F (9 °C)
below the lowest expected entering
loop temperature.
Table 3: Water limit guidelines
EWT Min.
(°F)
Min. flow rate
(GPM/ton)
Antifreeze
required?
50 1.5 No
40-50 3No
40-50 1.5 Yes
20-40 3Yes
Ground loop applications
All alcohols should be premixed
and pumped from a reservoir
outside of the building when
possible or introduced under the
water level to prevent fumes.
Calculate the total volume of
fluid in the piping system. Then
use the percentage by volume
shown in Table 4 for the amount
of antifreeze needed. Antifreeze
concentration should be checked
from a well mixed sample using a
hydrometer to measure specific
gravity.
Low water temperature
cutout setting
Zehnder Rittling’s heat pump
controller includes a user
configurable switch (DIP switch 2
on the PCB controller) to change
the low water temperature cutout
(FP1) setting between water
(30 °F) and Glycol (10 °F). When
loop conditions allow (antifreeze is
used), the FP1 DIP switch should
be set to the Glycol (10 °F) setting
to avoid nuisance faults.
Note:
 Low water temperature operation
requires extended range equipment.
Table 4: Antifreeze percentages by volume
Type
Minimum temperature for low temperature protection
10 °F
(-12 .2 °C)
15 °F
(-9.4 °C)
20 °F
(-6.7 °C)
25 °F
(-3.9 °C)
Methanol 25% 21% 16% 10%
Propylene glycol 38% 25% 22% 15%
Ethanol* 29% 25% 20% 14%
* Must not be denatured with any petroleum based product
14

Open loop ground
Typical open loop piping is shown
in Figure 11. Shut off valves
should be included for ease of
servicing. Boiler drains or other
valves should be “tee’d” into the
lines to allow acid flushing of the
heat exchanger. Shut off valves
should be positioned to allow flow
through the coax via the boiler
drains without allowing flow into
the piping system.
P/T plugs should be used so that
pressure drop and temperature
can be measured. Piping materials
should be limited to copper or
PVC SCH80.
Water quantity should be plentiful
and of good quality. Consult
Table 6 for water quality
guidelines. In ground water
situations where scaling could
be heavy or where biological
growth such as iron bacteria
will be present, an open loop
system is not recommended.
Heat exchanger coils may lose
heat exchange capabilities, over
time, due to build up of mineral
deposits. Heat exchangers must
only be serviced by a qualified
technician, as acid and special
pumping equipment is required. In
areas with extremely hard water,
the owner should be informed that
the heat exchanger may require
occasional acid flushing.
Water quality standards
Table 6 should be consulted
for water quality requirements.
Scaling potential should be
assessed using the pH/calcium
hardness method. If the pH <7.5
and the calcium hardness is less
than 100 ppm, scaling potential is
low. If this method yields numbers
out of range of those listed, the
Ryznar Stability and Langelier
Saturation indicies should be
calculated.
Use the appropriate scaling
surface temperature for the
application, 150 °F (66 °C) for
direct use (well water/open loop);
90 °F (32 °F) for indirect use.
A monitoring plan should be
implemented in these probable
scaling situations. Other water
quality issues such as iron
fouling, corrosion prevention and
erosion and clogging should be
referenced in Table 6.
Water control valve
Note the placement of the water
control valve in Figure 11. Always
maintain water pressure in
the heat exchanger by placing
the water control valve(s) on
the discharge line to prevent
mineral precipitation during the
off-cycle. Slow closing valves
are recommended to reduce
water hammer. If water hammer
persists, a mini-expansion tank
can be mounted on the piping to
help absorb the excess hammer
shock. Ensure that the total ‘VA’
draw of the valve can be supplied
by the unit transformer.
Ground water
applications
Applications 15

Ground water
applications
Water in
Water out
Insulated
Ball valve with PT port
Boiler drains
Flow regulator
Control valve
Insulated flex hose
Expansion tank
Return air
Supply air
Ball valve with PT
port and strainer
Note
 Due to the pressure and temperature
extremes, PVC SCH40 is not recommended.
Flow regulation
The preferred method of control
requires a flow control device
mounted on the outlet of the
water control valve. The device
is typically a brass fitting with
an orifice of rubber or plastic
material that is designed to allow
a specified flow rate. On occasion,
flow control devices may produce
velocity noise that can be reduced
by applying some back pressure
from the ball valve located on the
discharge line. Slightly closing
the valve will spread the pressure
drop over both devices, lessening
the velocity noise.
Water coil low temperature limit
setting
Zehnder Rittling’s heat pump
controller includes a user
configurable switch (DIP switch 2
on the PCB controller) to change
the low water temperature cutout
(FP1) setting between water
(30 °F) and Glycol (10 °F). When
loop conditions allow (antifreeze is
used), the FP1 DIP switch should
be set to the Glycol (10 °F) setting
to avoid nuisance faults.
Table 5: Water limit
guidelines
EWT Min.
(°F)
Min. flow
rate
(GPM/ton)
Antifreeze
required?
50 1.5 No
40-50 3No
40-50 1.5 Yes
20-40 3Yes
Figure 11: Typical open loop/well application
16

Proper maintenance of the
water loop is critical to both the
efficiency and longevity of the
system. This includes cleaning,
flushing and chemical treatment.
Three categories of issues can
arise from use of water including:
 Scale formation: resulting
from crystallization of
dissolved salts in the water.
These deposits form a
water-side insulation layer
that reduces heat transfer,
increases pressure drop and
may reduce flow.
 Metal decay: resulting from
corrosion or erosion
 Organic growths: slime and
algae can form under certain
environmental conditions. These
growths can have multiple adverse
impacts including reduced heat
transfer, increased pressure drop,
reduced flow and corrosion.
System water should be evaluated
for impurities. Testing is available
from independent labs, health
departments and/or state agencies.
Table 6 provides a list of water
characteristics, potential impurities
and effects and recommended
treatments.
Water quality standards
Table 6: Water characteristics
Impurity Copper coils Cupro-nickel
coils Result Application
Open recirculating Closed recirculating
Calcium and
magnesium salts
(hardness)
<350 PPM 350 PPM sea
water Scaling
1. Bleed off
2. Surface active agents such
as polyphosphates
3. Addition of acid
4. pH adjustment
No treatment required
Iron oxide Low levels only Moderate levels
Corrosion
1. Corrosion inhibiters
2. pH control
3. Proper materials of
construction
1. Corrosion inhibiters
(high concentrations)
2. Proper materials of
construction
pH 7.0 - 8.5 5 - 10
Hydrogen sulfide <10 PPM 10-50 PPM
CO2<50 PPM 50-75 PPM
Chloride <300 PPM 300-600 PPM
Total dissolved solids <100 PPM 1000-1500 PPM
Slime and algae Slime and algae can form under
certain environmental conditions
Reduced heat transfer
due to forming of
insulating coating or
pitting due to corrosion
1. Chlorinated phenols
2. Other biocides
3. Chlorine by hypochlorites ot
by liquid chlorine
No treatment required
Notes:
 Water quality varies widely from locale to locale. Consult a local water treatment specialist for specific treatment recommendations.
 Cupro-nickel is recommended if iron bacteria, suspended solids, or dissolved oxygen is high.
 If concentration of corrosives exceeds Cupro-nickel maximums the potential for serious corrosion problems exist.
Potential problems can be
mitigated by:
 Using cupro-nickel coils
 Maintaining flow rates of
<4 GPM per ton to minimize
potential erosion
The Zehnder Rittling Water
Quality Table provides water
quality requirements for Zehnder
Rittling coaxial heat exchangers.
When water properties are
outside of those requirements,
an external secondary heat
exchanger must be used to
isolate the heat pump heat
exchanger from the unsuitable
water. Failure to do so will void
the warranty for the coaxial heat
exchanger.
Water quality standards 17

Table 7: HPSH series electrical data, PSC motors
Model Voltage
code
Rated
voltage
(V/Hz/Ph)
Voltage
min./
max.
Compressor Fan motor Total
unit
FLA
Disconnect
Size
Min.
circuit
amps
MOP
Max.
fuse/
HACR
size
RLA LRA Type Power
(HP) FLA
009 A208-230/60/1 187/253 3.8 20.0 1/12 0.9 4.7 15.0 5.6 9.4 15 15
012 A208-230/60/1 187/253 5.0 27.0 1/12 0.9 5.9 15.0 7.1 12.1 15 15
015 A208-230/60/1 187/253 5.4 28.0 1/6 1.2 6.6 15.0 8.0 13.4 15 15
018 A208-230/60/1 187/253 6.6 43.0 1/6 1.2 7.8 15.0 9.5 16.1 15 15
024
A208-230/60/1 187/253 13.5 58.3 1/4 1.6 15.1 20.0 18.4 31.9 30 30
B265/60/1 239/292 9.0 54.0 1/4 1.4 10.4 15.0 12.7 21.7 20 20
C208-230/60/3 187/253 7.1 55.4 1/4 1.6 8.7 15.0 10.4 17. 5 20 20
D460/60/3* 414/506 3.5 28.0 1/4 1.4 4.9 15.0 5.8 9.3 15 15
030
A208-230/60/1 187/253 12.8 58.3 1/4 1.6 14.4 15.0 17.6 30.4 30 30
B265/60/1 239/292 9.6 54.0 1/4 1.4 11.0 15.0 13.4 23.0 25 25
C208-230/60/3 187/253 7.7 55.4 1/4 1.6 9.3 15.0 11. 2 18.9 20 20
D460/60/3* 414/506 3.6 28.0 1/4 1.4 5.0 15.0 5.9 9.5 15 15
036
A208-230/60/1 187/253 14.1 7 7.0 3/5 3.5 17.6 20.0 21.1 35.2 35 35
B265/60/1 239/292 12.2 72.0 3/5 3.0 15.2 20.0 18.3 30.5 30 30
C208-230/60/3 187/253 9.0 71.0 3/5 3.5 12.5 15.0 14.8 23.8 25 25
D460/60/3* 414/506 5.6 38.0 3/5 3.0 8.6 15.0 10.0 15.6 15 15
042
A208-230/60/1 187/253 16.7 79.0 3/5 3.5 20.2 30.0 24.4 41.1 40 40
B265/60/1 239/292 13.5 72.0 3/5 3.0 16.5 20.0 19.9 33.4 35 35
C208-230/60/3 187/253 10.4 73.0 3/5 3.5 13.9 15.0 16.5 26.9 25 25
D460/60/3* 414/506 5.8 38.0 3/5 3.0 8.8 15.0 10.3 16.1 15 15
052
A208-230/60/1 187/253 19.9 109.0 3/4 4.6 24.5 30.0 29.5 49.4 50 50
B265/60/1 239/292 16.3 98.0 3/4 4.2 20.5 30.0 24.6 40.9 40 40
C208-230/60/3 187/253 13.1 83.1 3/4 4.6 17.7 20.0 21.0 34.1 35 35
D460/60/3* 414/506 6.1 41.0 3/4 4.2 10.3 15.0 11.8 17.9 20 20
062
A208-230/60/1 187/253 25.0 134.0 3/4 4.6 29.6 30.0 35.9 60.9 60 60
B265/60/1 239/292 21.3 130.0 3/4 4.2 25.5 30.0 30.8 52.1 50 50
C208-230/60/3 187/253 15.9 110.0 3/4 4.6 20.5 30.0 24.5 40.4 40 40
D460/60/3* 414/506 7.1 52.0 3/4 4.2 11. 3 15.0 13 .1 20.2 20 20
072
A208-230/60/1 187/253 26.3 134.0 3/4 4.6 30.9 40.0 37. 5 63.8 60 60
B265/60/1 239/292 19.9 128.0 3/4 4.2 24.1 30.0 29.1 49.0 50 50
C208-230/60/3 187/253 15.6 110.0 3/4 4.6 20.2 30.0 24.1 39.7 40 40
D460/60/3* 414/506 7. 8 52.0 3/4 4.2 12.0 15.0 14.0 21.8 20 20
* Neutral connection required. All 460V units require a four wire + ground supply (3 hot, 1 neutral, 1 ground). Fan motors are 265V/60Hz/1Ph.
Wired between one hot leg and neutral.
Electrical: Line voltage
18