Stulz CeilAiR Series User manual

CeilAiR Series
Supplemental Air Conditioners
3.5 – 35 kW Systems
Ceiling Mounted, 60 Hz Data
Installation, Operation and Maintenance Manual

ii
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
Notice
This document contains information protected by copyright. All rights are reserved. The owner ofthe equipment for which this
manual is written may photocopy the contents of this manual for internal use only. No part of this document may be photocopied,
reproduced, or translated into another language for use by anyone other than the owner of the equipment for which this manual is
written without the prior written consent of STULZ Air Technology Systems, Inc. (STULZ).
This document contains confidential and proprietary information of STULZ Air Technology Systems, Inc. Distributing or photocopying
this document for external distribution is in direct violation of U.S. copyright laws and is strictly prohibited without the express written
consent of STULZ.
Unpublished — rights reserved under the copyright laws of the United States and of other countries.
Other brands and tradenames are trademarks of their respective owners.
Copyright 2017 by STULZ Air Technology Systems, Inc.
Printed in the United States of America.
All rights reserved.
STULZ Air Technology Systems, Inc.
1572 Tilco Drive
Frederick, MD 21704 USA
Model Nomenclature
OHSXXXXXXX
System
Nominal Capacity
in 1,000’s of
BTU/H
Configuration Options
OHS = CeilAiR
Overhead System
012, 018, 024, 032,
040, 048, 060, 072,
084, 120
D( ) = Dual Circuit
H( ) = Horizontal Discharge
(“HSeries”)
AHU = Air Handling Unit
AR = Air-Cooled Remote (Split)
AS = Air-Cooled Self-Contained
C = Chilled Water System
G = Glycol-Cooled
W = Water Cooled
AWS = Alternate Water Source
FC = Free Cooling
LP = Low Profile Configuration
SF = Same-Face Air Pattern
SP = Special Configuration*
OHS 040 H G FC
* Please consult factory for additional information.
Example: OHS040HGFC
Overhead System, 40,000 BTU/H Capacity, Horizontal Discharge, Glycol Cooled with optional Free Cooling: OHS040GFC

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
iii
Contents
1.0 Introduction ................................................. 1
1.1 General ..............................................................................1
1.2 Product Description ......................................................1
1.3 Control Devices...............................................................1
1.4 Safety .................................................................................1
1.4.1 General...............................................................................1
1.4.2 Safety Summary..............................................................2
1.5 General Design................................................................3
1.5.1 Electric Box Access.......................................................3
1.5.2 Coil(s) ..................................................................................4
1.5.3 Blower................................................................................4
1.5.4 Temperature Sensor......................................................4
1.6 Optional Equipment.......................................................4
1.6.1 Humidistat/Dehumidistat............................................4
1.6.2 Temperature/Humidity Sensor..................................5
1.6.3 Heaters ..............................................................................5
1.6.4 Humidifier..........................................................................5
1.6.5 Condensate Pump.........................................................5
1.6.6 Smoke Detector .............................................................5
1.6.7 Firestat ..............................................................................5
1.6.8 Water Detector ...............................................................5
1.7 Free-cooling Operation................................................5
1.8 AWS Operation................................................................7
2.0 Installation ................................................... 8
2.1 Receiving the Equipment.............................................8
2.2 Site Preparation..............................................................8
2.3 Rigging...............................................................................9
2.4 Mounting ...........................................................................9
2.4.1 Indoor Equipment........................................................10
2.4.2 Outdoor Equipment....................................................10
2.4.3 Controls ..........................................................................10
2.4.3.1 ATech Programmable Thermostats.....................10
2.4.3.2 Advanced STULZ E² Controller .............................12
2.4.4 Optional Equipment....................................................12
2.4.4.1 Condensate Pump (Field Installed).......................12
2.4.4.2 Non-Fused Service Switch......................................12
2.4.5 Remote Sensors..........................................................12
2.4.5.1 Remote Temperature Sensor (ATech) ................12
2.4.5.2 Remote Temperature/Humidity Sensor (E²)......13
2.4.6 Humidistat/Dehumidistat (Used with
ATech1.1/1.2 Thermostat) ....................................13
2.4.7 Spot Water Detector ..................................................14
2.4.8 Cable Type Water Detector......................................14
2.5 Air Distribution Connection......................................14
2.5.1 Spot Cooler....................................................................14
2.5.2 Ducted Systems...........................................................14
2.6 Piping Connections ....................................................14
2.6.1 Refrigerant.....................................................................14
2.6.1.1 Self-Contained Systems...........................................14
2.6.1.2 Split Systems ................................................................14
2.6.1.3 Remote Air Cooled Condensers (AR Models)....17
2.6.1.4 Remote Air Cooled Condensing Units
(AHU Models)................................................................17
2.6.2 Chilled Water, Water/Glycol and Hot Water
Reheat Piping...............................................................17
2.6.3 Condensate Drain Line..............................................18
2.6.3.1 Gravity Drain..................................................................18
2.6.3.2 Condensate Pump......................................................18
2.6.4 Humidifier (Optional) ..................................................18
2.7 Utility Connections......................................................18
2.7.1 Main Power....................................................................18
2.7.1.1 Single-Phase Units 208/230V.............................19
2.7.1.2 Single-Phase Units 277V........................................19
2.7.1.3 Three-Phase Units......................................................19
2.7.2 Controls ..........................................................................20
2.7.2.1 ATech 1.1 Programmable Thermostat...............20
2.7.2.2 ATech 1.2 Programmable Thermostat...............20
2.7.3 Air-Cooled Split Systems..........................................20
2.7.3.1 Remote Condenser.....................................................24
2.7.3.2 Remote Condensing Unit .........................................24
2.7.4 Water/Glycol Systems...............................................24
2.7.5 Remote Shut Down ....................................................24
2.7.6 Optional Equipment....................................................24
2.7.6.1 Condensate Pump......................................................24
2.7.6.2 Humidistat/Dehumidistat.........................................24
2.7.6.3 Remote Water Detector............................................25
2.7.6.4 Remote Temperature Sensor (ATech).................25
2.7.6.5 Remote Temperature/Humidity Sensor (E2)......25
2.8 System Charging Procedures.................................25

iv
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
2.8.1 Water/Glycol Systems...............................................25
2.8.1.1 Pump ...............................................................................25
2.8.2 DX Unit Charging Requirements............................25
2.8.3 Remote Air-Cooled Systems (AR/AHU)..............26
2.8.4 R407C/R410A Refrigerant ..................................26
2.8.5 Estimating Refrigerant Charge...............................26
2.8.6 Preparing System For Charging.............................27
2.8.6.1 Evacuate the System..................................................27
2.8.7 Refrigerant Charging Procedures .........................28
2.8.7.1 Initial System Charge .................................................28
2.8.7.2 Fine Tuning The System Charge.............................28
2.8.7.3 0 ºF Fan Cycling and -20 ºF Variable Speed
Control.............................................................................29
2.9 Refrigerant Characteristics......................................30
2.9.1 Pressure/Temperature Settings............................30
2.9.2 Saturated Refrigerant Pressure Tables...............30
2.10 System Settings and Adjustments ........................31
2.10.1 Low/High Pressure Limit Switch ..........................31
2.10.2 Head Pressure Controls—Air Cooled
Systems ..........................................................................31
2.10.2.1 Condenser Fan Cycling (Condenser Model
SCSAA, 0 °F)...............................................................31
2.10.2.2 Condenser Multi-Speed Fan Switch (Model
HESCAA , 0 °F ) .........................................................31
2.10.2.3 Variable Condenser Fan Speed (Condenser
Model SCSSA, -20 °F).............................................31
2.10.2.4 Intelligent Control (Condenser Model SCSEC
Only, -20 °F)..................................................................31
2.10.2.5 Flooded Head Pressure Control (Condenser
Model SCSAA With Fan Cycling, -30 °F) ..........32
2.10.2.6 Flooded Head Pressure Control (Condenser
Model HESCAA , -30 °F) .......................................32
2.10.3 Head Pressure Controls—Water/Glycol Cooled
Systems ..........................................................................32
2.10.4 Humidifier Adjustment...............................................32
2.10.5 Blower Adjustment .....................................................33
2.10.5.1 Belt Drive Blower.........................................................33
2.10.5.2 EC Fan (Optional).........................................................33
2.10.6 Thermal Expansion Valve..........................................33
2.10.7 Hot Gas Reheat (Optional)........................................34
2.10.8 Hot Gas Bypass (Optional).......................................34
2.10.8.1 Snap Acting Hot Gas Bypass .................................34
2.10.8.2 Full Floating Hot Gas Bypass..................................34
3.0 Commissioning, Operation And Decommis-
sioning ........................................................ 35
3.1 Commissioning the Unit ............................................35
3.1.1 Commissioning Steps................................................35
3.2 Operating the Unit.......................................................36
3.2.1 Shutdown Procedure.................................................36
3.2.2 Start-up Procedure ....................................................36
3.3 Programming the Thermostat.................................36
3.3.1 ATech Controller.........................................................36
3.3.2 E² Controller..................................................................36
3.4 Decommissioning the Unit.......................................36
3.4.1 Recovering Refrigerant.............................................37
3.4.2 Labeling Decommissioned Equipment................37
4.0 Maintenance............................................... 37
4.1 Periodic General Maintenance ...............................37
4.1.1 A/C Unit..........................................................................38
4.1.1.1 Compressor...................................................................38
4.1.1.2 Heater..............................................................................38
4.1.1.3 Air Filters ........................................................................38
4.1.1.4 Blower.............................................................................38
4.1.1.5 Coils .................................................................................38
4.1.1.6 Drain Pan........................................................................38
4.1.1.7 Condensate Pump .....................................................39
4.1.1.8 Humidifier.......................................................................39
4.1.2 Condenser/Condensing Unit..................................39
4.2 Troubleshooting...........................................................40
4.3 Field Service..................................................................43
4.3.1 Leak Detection.............................................................43
4.3.2 Leak Repair...................................................................43
4.3.3 Refrigerant Piping.......................................................43
4.3.4 General Common Repairs/Component
Replacement.................................................................43
4.3.4.1 Compressor Failure ...................................................43
4.3.4.2 Standard Cleanout Procedure................................44
4.3.4.3 Burn-Out/Acidic Cleanup Procedure ..................44
4.3.4.4 Humidifier Cylinder Replacement..........................44
4.3.4.5 Air Filter Replacement...............................................45
5.0 Product Support ........................................ 45
5.1 Factory Authorized Start Up/Warranty
Inspection ......................................................................45
5.2 Technical Support .......................................................45

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
v
Figures
Figure 1. ATech Digital Thermostats.................................1
Figure 2. E2Microprocessor Controller and Display ....1
Figure 3. CeilAiR OHS032AR (Access Panels Re-
moved) ........................................................................4
Figure 4. Free Cooling Diagram............................................6
Figure 5. Alternate Water Source Diagram ......................7
Figure 6. Typical Installation ..................................................9
Figure 7. ATech Controller Installation...........................10
Figure 8. Spot Cooler Grille.................................................11
Figure 9. Ducted System Typical Air Patterns ..............11
Figure 10. Temperature Sensor for ATech ......................12
Figure 11. Temperature/Humidity Sensor for E2
Controller................................................................13
Figure 12. Condensate Pump...............................................18
Figure 13. Sample Nameplate..............................................19
Figure 14. ATech 1.1 (top) and 1.2 (bottom) Controller
Wiring Contacts....................................................20
Figure 15. ATech 1.1 Control Wiring.................................21
Figure 16. ATech 1.2 Control Wiring.................................21
Figure 17. Interconnection Field Wiring Remote Con-
denser......................................................................22
Figure 18. Interconnection Field Wiring Remote Con-
densing Unit...........................................................22
Figure 19. Interconnection Field Wiring Remote Con-
densing Unit with Dual Compressors............23
Figure 20. Interconnection Field Wiring Glycol
Systems...................................................................23
Figure 21. Belt Drive Blower ................................................33
Tables
Table 1. Pipe Equivalent Lengths....................................15
Table 2. Recommended Discharge Line Sizes For
R407C Refrigerant.............................................15
Table 3. Recommended Discharge Line Sizes For
R410A Refrigerant .............................................15
Table 4. Recommended Liquid Line Sizes For R407C
Refrigerant (Condenser to Receiver )............16
Table 5. Recommended Liquid Line Sizes For R410A
Refrigerant (Condenser to Receiver) ............16
Table 6. Recommended Suction Line Sizes For R407C
Refrigerant ............................................................16
Table 7. Recommended Suction Line Sizes For R410A
Refrigerant.............................................................16
Table 8. Weight (lb) of Refrigerant per 100 ft of Type L
Tubing.......................................................................26
Table 9. Weight (lb) of Refrigerant by OHS Model ....27
Table 10. Refrigerant Pressure/Temperature
Settings ...................................................................30
Table 11. Saturated Refrigerant Pressure......................30
Table 12. Troubleshooting Table ........................................40
5.3 Obtaining Warranty Parts .........................................46
5.4 Obtaining Spare/Replacement Parts ..................46
Appendix A - OHS Preventive Maintenance
Inspection Checklist.................................. 47
Appendix B - Acronyms and Abbreviations............... 50

vi
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
1
1.0 INTRODUCTION
1.1 General
The CeilAiR®ceiling-mounted air conditioning system
documented in this manual is designed and manufactured
by STULZ Air Technology Systems, Inc. (STULZ).
STULZ CeilAiR overhead air conditioning systems (OHS)
are constructed using the finest available materials/com-
ponents, state-of-the-art technology and quality crafts-
manship. The unit will provide years of trouble free service
if installed and maintained in accordance with this manual.
Damage to the unit from improper installation, operation
or maintenance is not covered by the warranty. Due to
advances in technology, components described herein are
subject to change without notice.
All STULZ CeilAiR OHS systems and CyberAiR centrifugal
condensers are designed to be installed indoors, unless
otherwise noted on the equipment. Propeller-type con-
densers, condensing units, drycoolers and pump packages
are designed for outdoor use.
1.2 Product Description
STULZ CeilAiR OHS systems are designed to be the most
versatile and flexible ceiling-mounted air conditioning
systems in the industry. The unit is available in air-cooled,
water-cooled, glycol-cooled and chilled-water configura-
tions. The cooling capacity in BTU/H will depend on the
unit size, which can range from 1 to 10 tons (3.5–35 kW),
and can be either a single stage or dual stage unit.
In addition to cooling, other functional modes of opera-
tion include heating, humidification, dehumidification and
filtration to provide complete environmental control of a
conditioned space. The cabinet configuration is available in
a 2 ft x 4 ft frame for units ranging from 12,000 to 40,000
BTU/H (spot cooler or ducted) or a larger frame for units
ranging from 48,000 to 120,000 BTU/H (ducted only).
For ducted units, there are three basic configurations of
airflow patterns: 90º/right angle, straight-through and in/
out-same-face (see Figure 9 on page 11). Refer to the
installation drawing provided with the unit for the type of
cabinet configuration and for the layout dimensions.
1.3 Control Devices
STULZ offers a variety of control devices for CeilAiR OHS
series systems. Control interfaces are typically remotely
mounted to a wall or control panel.
The default control device for OHS units is the ATech
digital thermostat, which provides basic control of the
system. Slightly different wiring is used with the thermostat
in single- and dual-stage units, as shown in Figure 14 on
page 20. The single-stage version is the ATech 1.1.
The two-stage version is the ATech 1.2. An operating
manual for the thermostat is provided with the unit under
separate cover.
Figure 1. ATech Digital Thermostats
The advanced STULZ E² microprocessor controller is
also available for OHS systems. This controller provides
enhanced features for more comprehensive control of
the unit. These features include: full alarm system; input/
output monitoring status; full integrated control of heating,
cooling, humidification, and dehumidification and remote
communication with building management systems. An
operating manual for the controller is provided with the unit
under separate cover.
Figure 2. E2Microprocessor Controller and Display
1.4 Safety
1.4.1 General
STULZ Air Technology Systems, Inc. uses notes, cautions
and warnings in its manuals to draw attention to important
operating and safety information.
A bold text NOTE alerts you to an important detail.
A bold text CAUTION provides information that is impor-
tant for protecting your equipment and performance. Be
especially careful to read and follow all cautions that apply
to your application.

2
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
A bold text WARNING provides information important for
protecting you from harm. Pay very close attention to all
warnings that apply to your application.
precedes a general WARNING or CAUTION safety
statement.
precedes an electrical shock hazard WARNING or
CAUTION safety statement.
1.4.2 Safety Summary
The following warnings and cautions appear in this manual.
Before performing any installation, operation, maintenance
or troubleshooting procedure, read and understand all
relevant cautions and warnings. Maintenance and/or repair
procedures must be performed by a journeyman refrigera-
tion mechanic or air conditioning technician.
WARNING
Never work on electrical equipment unless another
person who isfamiliarwith the operation and hazards
of the equipment and competent in administering
first aid is nearby.
WARNING
All personnel working on or near equipment should
be familiar with hazards associated with electrical
maintenance. Safety placards/stickers have been
placed on the unit to call attention to all personal
and equipment damage hazard areas.
WARNING
When working on electrical equipment, remove all
jewelry, watches, rings, etc.
WARNING 1
Hazardous voltage will still be present inside the
electric box at the motor starter protectors and
circuit breakers, even with the unit turned off at the
E2controller. To isolate the unit for maintenance,
turn offpowerat the main power disconnect switch.
Always disconnect main power prior to performing
any service or repairs.
WARNING
Alock-out/tag-out procedure should befollowedto
ensurethat power is not inadvertently reconnected.
WARNING
To prevent personal injury, stay clear of rotating
components, as automatic controls may start them
unexpectedly. Turn off power to the unit unless you
are performing teststhat require power.With power
and controls energized,the unit could begin operat-
ing at any time.
WARNING
Never lift any component in excess of 35 lb without
help. If a lifting device is used to move a unit, ensure
it is capable of supporting the wight of the unit.
WARNING
Do not allow the unit to swing while suspended
from a lifting device. Failure to observe this warning
may result in injury to personnel and damage to the
equipment.
WARNING
Neveroperate the unitwith any cover, guard, screen
panel, etc., removed unlessthe instructions specifi-
cally state otherwise, then do so with extreme cau-
tion to avoid personal injury.
WARNING
Refrigerant is used with this equipment. Death or
serious injury may result if personnel fail to observe
proper safety precautions. Great care must be ex-
ercised to prevent contact of liquid refrigerant or
refrigerant gas, discharged underpressure,with any
part ofthe body.The extremelylowtemperature re-
sulting from the rapid expansion ofliquid refrigerant
orpressurized gascan cause sudden andirreversible
tissue damage.
At a minimum, all personnel should wear thermal
protective gloves and face-shield/goggles when
working with refrigerant. Application of excessive
heat to any componentwill cause extreme pressure
and may result in a rupture.
Exposure of refrigerant to an open flame or a very
hot surface may cause a chemical reaction that
forms hydrofluoric acid orcarbonyl fluoride, a highly
poisonous and corrosive gas commonly referred to
as fluorophosgene. In its natural state, refrigerant is
a colorless, odorless vapor with no toxic character-

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
3
istics. It is heavier than air and will disperse rapidly
in a well-ventilated area. In an unventilated area it
presents a danger as a suffocant.
Always reviewthe manufacturer’s Safety DataSheet
(SDS) provided withthe unit before performing work
involving refrigerant.
WARNING
Do not use cleaning solvents near open flame or
excessive heat. Wear eye protection when blow-
ing solvent from parts. The pressure-wash should
not exceed 30 psig. Solvent solutions should be
disposed of in accordance with local and state
regulatory statutes.
WARNING
Certain maintenance or cleaning procedures may
call for the use and handling of chemicals, solvents,
or cleansers. Always refer to the manufacturer’s
Safety Data Sheet (SDS) prior to using these ma-
terials. Clean parts in a well-ventilated area. Avoid
inhalation ofsolvent fumes and prolonged exposure
of skin to cleaning solvents. Wash exposed skin
thoroughly after contact with solvents.
WARNING
When performing soldering or desoldering
operations, make certain the refrigeration system
is fully recovered and purged and dry nitrogen is
flowing through the system at the rate of not less
than 12 CFM.
WARNING
Cooling coils (and associated piping circuits) are
pressurized (up to 100 psi) and sealed when they
leavethe factory. Before installingthe interconnect-
ing piping, observe appropriate safety precautions
and releasethe pressure via an available stem valve
or Schrader valve prior to uncapping the pipes.
CAUTION
When the air conditioner operates in cooling mode
the return air intake and discharge (supply) must be
free of obstructions. Ensure panels are secure and
latched into position.
CAUTION
After interconnecting piping is installed, the piping
system must be cleaned. If solvents/cleaning solu-
tions are used, ensure they are completely flushed
from the piping before connecting it to the unit.
Failure to do so will result in equipment problems.
CAUTION
When installing and filling a chilled water or water/
glycol loop, all air must be bled from the piping
system.
CAUTION
Do not use chloride-based water conditioning ad-
ditives in the condensate drain pans. They cause
corrosion to occur on the coil fins.
CAUTION
When transporting and installing theA/C unit, it must
be kept in its normal, horizontally-installed position.
Ifthe unit is not kept level and horizontal, damage to
the compressor(s) will result.
1.5 General Design
The CeilAiR unit is housed in an aluminum frame cabinet
and is rated for indoor use. Removable panels are located
on the front and rear ofthe cabinet for easy access to all
components. Additional access may be obtained to some
components through the bottom of the unit on spot cooler
configurations. The unit has an electric box inside the
cabinet with a removable panel for accessing the electri-
cal components. Operator controls may be conveniently
located on a wall within the space to be conditioned.
NOTE
Customer specified, non-standard features or de-
sign variations may not be described in this manual.
Referto the installation and electrical drawings sup-
plied withyourunit fordetails on additional feature(s).
In some cases, an addendum tothis manual mayalso
be included to further describe the feature(s).
1.5.1 Electric Box Access
Electrical components are protected in an enclosure
located in the cabinet behind an access panel. Before
opening the access panel, turn off power at the main power
service disconnect switch. This removes power from the E2
controller (if present) and shuts the unit off.

4
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
1.5.2 Coil(s)
The cooling and optional hot water reheating coils are alu-
minum finned/copper tube construction. The coils are leak
tested and cleaned before installation at the factory.
1.5.3 Blower
The unit is equipped with a centrifugal blower with forward
curved blades. The blower is contained in a double-width,
double-inlet housing. The blower is dynamically and stati-
cally balanced to minimize vibration. The blower motor is
ODP industrial duty and utilizes permanently lubricated ball
bearings.
Smaller CeilAiR units (models OHS012/040) use
direct drive blowers (except “H”-series models con-
figured for horizontal discharge). Larger units (models
OHS048/120) and horizontal discharge units (models
OHS012/040H), use a belt-driven blower. The belt-driv-
en blower motor is mounted on an adjustable base for belt
tensioning and is furnished with an adjustable pitch sheave
to adjust blower speed (see Figure 21 on page 33).
1.5.4 Temperature Sensor
As a standard for systems utilizing a wall mounted ATech
thermostat, the temperature sensor is built into the thermo-
stat for room air control. The sensor monitors the room air
conditions and provides input signal(s) to the thermostat.
The thermostat manages the operation ofthe A/C unit
consistent with the setpoints entered.
As an option, the temperature sensor may be shipped loose
for field installation in the room to be conditioned. Refer
to the electrical drawing supplied with your unit for details
specific to your system.
1.6 Optional Equipment
1.6.1 Humidistat/Dehumidistat
As an option for systems employing an ATech 1.1 or
ATech 1.2 thermostat, a room mounted humidistat and/
or dehumidistat may be shipped loose for field installation.
Each device has an adjustment dial on the front where the
operator selects the desired setpoint.
If an optional humidifier is selected, the humidistat is
included to control its operation. The humidistat controls
the humidifier’s operation independently of the control
thermostat; however, the blower must be on for the humidi-
fier to operate.
If the heat/reheat option is selected, a dehumidistat is provided.
If room humidity rises above setpoint when the demand for
cooling is satisfied, the dehumidistat signals the compressor
Figure 3. CeilAiR OHS032AR (Access Panels Removed)

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
5
to turn on, removing humidity. At the same time, the heater(s)
are turned on to offset the cooling effect, thus maintaining
the temperature of the space to be conditioned. Refer to the
electrical drawing supplied with your unit for details specific to
your system.
1.6.2 Temperature/Humidity Sensor
As a standard for systems that use the E² microprocessor
controller, a temperature/humidity (T/H) sensor is typically
factory mounted in the return airstream for room air control.
As an option, the T/H sensor may be shipped loose for field
installation. See 2.7.6.5 on page 25 and the electrical
drawing supplied with your unit for details specific to your
system.
1.6.3 Heaters
The OHS unit may incorporate heaters for reheating the
supply air as required to offset the sensible cooling of the
system during the dehumidification cycle and for the auto-
matic heating mode. Electric resistance heating elements
are factory installed in the supply airstream to heat the sup-
ply air. The heating elements are protected with line fuses
(manual and/or automatic), thermal fuse links and over-
temperature safety switches which automatically reset.
As an option, hot water reheat may be selected for auto-
matic sensible reheating during the dehumidification cycle.
A hot water heating coil is factory installed in the supply air-
stream. A valve is provided to control the flow of hot water
through the coil to maintain the correct reheat temperature.
Hot gas reheat may be selected (for CeilAiR units with DX
cooling only) for automatic sensible reheating during the
dehumidification cycle. Hot compressor discharge gas
is diverted from the condenserto a hot gas heating coil
mounted in the supply airstream.
1.6.4 Humidifier
CeilAiR systems may utilize an optional electrode steam
humidifier. The humidifier is factory installed inside the air
conditioner and includes fill and drain valves and associat-
ed piping. Operation of the humidifier’s fill and drain cycles
is based on water conductivity and is maintained by the
humidifier controller. An operating manual for the humidi-
fier is provided with the unit under separate cover. Refer to
that manual for detailed information about operating the
humidifier.
1.6.5 Condensate Pump
An optional, factory-installed condensate pump may be
provided. The pump automatically eliminates condensate
and humidifier flush water (if applicable) from the drain
pan. Should an overflow occur in an E²-based system, the
pump overflow safety switch triggers a contact signal to
the controller that indicates the alarm condition, and the
controller automatically shuts down the compressor and
optional humidifier until the condition is corrected. The
blower(s) will continue to operate. In an ATech system, the
pump safety switch is wired directlyto the OHS remote
stop/start terminals to cut power to the system.
1.6.6 Smoke Detector
A smoke detector may be mounted in the return airstream
to sense the presence of smoke and, when smoke is
detected, shut down the air conditioner, either via the E²
controller or in ATech systems via connection to the OHS
remote stop/start terminals.
1.6.7 Firestat
A fire detector (firestat) may be mounted in the return
airstream to sense high return airtemperature indicative of
a fire. The system shuts down, either via the E² controller
or, in an ATech system, via connection to the OHS remote
stop/start terminals. Following activation, the firestat must
be manually reset using the reset button on the firestat
before restarting the unit.
1.6.8 Water Detector
As an option, STULZ offers spot type or strip/cable type
water detectors. In units equipped with an E² controller,
when water is detected the controller turns off cooling and
humidification, while the blower(s) continue to operate. The
unit will automatically restart when the condition is correct-
ed. In units equipped with an ATech thermostat, the water
detector is wired to the OHS remote stop/start terminals
and power to the system is cut when water is detected.
1.7 Free-cooling Operation
The free-cooling (FC) configuration illustrated in Figure 4
is available to minimize the use of compressor operation
during low ambient conditions for system energy savings.
An FC system utilizes a remote drycooler to provide water/
glycol coolant to a free-cooling coil positioned within a DX
refrigerant system. If outdoor air temperatures permit free-
cooling operation (adjustable user setpoint), the free-cool-
ing mode is enabled to take advantage of the low ambient
conditions to provide cooling with partial use or without the
use of the system compressor(s). Free-cooling provides
an excellent opportunity for reduced operational cost by
reducing the compressor operating hours. The free-cooling
sequence is enabled if the entering fluid temperature is be-
low the user adjustable free-cooling-enable setpoint and
the return air temperature rises to the free-cooling setpoint

6
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
plus dead band. The drycooler pump activates and the 3-way control valve directs chilled water/glycol coolant to the FC
coil. The outdoor fluid cooler is controlled by first switching the leaving fluid control setpoint from typical DX heat rejection to
free-cooling control (adjustable setpoint, ambient air) and by controlling the leaving fluid to its user-adjustable setpoint. The
free-cooling control valve opens proportionally to the demand for cooling based on the return air temperature’s deviation
from setpoint.
If the return airtemperature continues to rise, the free-cooling valve position eventually reaches 100% open, maximizing the
flow of coolant through the free-cooling coil. Continued operation in this position indicates the A/C unit is unable to lower
the air temperature to the desired setpoint in the free-cooling mode.
Figure 4. Free Cooling Diagram
The compressor activates if the DX cooling stage enable-temperature setpoint has been reached or if the control valve posi-
tion reaches 100% open for 240 seconds (default compressor-on time delay). The free-cooling circuit and the compressor
operate in parallel on dual-circuit units to provide maximum cooling. The 3-way control valve continually modulates the flow
of coolant in response to temperature with the compressor running.
The compressor cycles off based on the normal compressor temperature cut-out settings once the setpoint is maintained.

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
7
As the outside air temperature increases above the ambient air switch-over setting, the fluid cooler controls cycle back to
typical DX heat rejection allowing the leaving fluid control setpoint to increase above the prevailing ambient conditions. The
indoor unit’s inlet fluid temperature sensor monitors the fluid temperature and deactivates the free-cooling mode once the
fluid temperature increases above the user adjustable enable setpoint. The compressor system becomes the primary cool-
ing source and will activate if the return air temperature increases above the setpoint.
1.8 AWS Operation
The AWS (Alternate Water Source) configuration illustrated in Figure 5 utilizes an independent chilled water source to pro-
vide coolant to an AWS cooling coil in the A/C unit. If AWS cooling is unable to handle the load, the separate DX refrigeration
circuit can be utilized to assist. Similar to FC operation (see Section 1.7), when return air temperature rises to the AWS cut-in
temperature setpoint and if the chilled water inlet temperature is 55 °F or less (adjustable), AWS cooling activates (the AWS
control valve opens) and remains on while the activation conditions exist.
Figure 5. Alternate Water Source Diagram

8
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
If the return airtemperature rises to the compressor cut-in
setpoint or if the AWS control valve reaches 100% open for
240 seconds (default compressor-on time delay), the com-
pressor turns on and operates in parallel with AWS cooling.
The compressor runs until the normal compressor cut-out
setpoint temperature is reached provided the minimum run
time expires.
If the chilled water inlet temperature rises above 55 °F,
AWS cooling turns off (the control valve closes). When the
DX cooling stage-enable temperature setpoint is reached,
the compressorturns on and becomes the primary source
of cooling.
In the event of loss of water flow during AWS operation, the
AWS control valve is closed and the compressor system
becomes the primary cooling source. It will activate if the
return air temperature increases above the setpoint.
2.0 INSTALLATION
2.1 Receiving the Equipment
Your CeilAiR OHS system has been tested and inspected
prior to shipment. To ensure the equipment is received in
excellent condition, visually inspect the equipment im-
mediately upon delivery. Carefully remove the shipping
container and all protective packaging. Remove the access
panels and thoroughly inspect the unit interior for any signs
of transit-incurred damage. If there is shipping damage, it
must be noted on the freight carrier’s delivery forms before
signing for the equipment. Anyfreight claims must be done
through the freight carrier. STULZ ships all equipment
Factory FOB. STULZ can assist in the claim filing process
with the freight carrier. Should any damage be present,
notify STULZ Product Support prior to attempting any
repairs. Refer to section 5.0 on page 45 of this manual
for instructions.
A data package is included with your unit. It contains this
manual, system drawings, applicable material SDS’s, other
component manuals, warranty registration and other appli-
cable instructions based on the configuration and options
provided with the unit. The data package has been placed
in the unit in a clear plastic bag. The documents need to be
retained with the unit for future reference.
NOTE
Items that have been shipped loose, such as remote
sensors, vibration isolators, and so on, are shipped
inside the airconditioner unless specified otherwise
bythe customer. Grilles (if applicable) are placed on
top of the air conditioner inside the unit’s carton.
Remove and storethese items in a safe place unless
you are using them immediately.
2.2 Site Preparation
CeilAiR systems are designed with easy service access in
mind. Component access panels are located on the front
and rear sides of the equipment. Additional access to some
components may be obtained through the bottom of the
unit on spot cooler configurations. These units can be fully
serviced in the ceiling plenum. In order to have full service
access, the air conditioner must be located so that ad-
equate space is provided in front of all access panels.
NOTE
Working clearance requirements need to be estab-
lished prior to the mounting of the unit. Refer to the
National Electrical Code and local codes.

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
9
To minimize the effects of the environment surrounding
the conditioned space, certain steps must be taken. This
is especially true for critical/precision room preparation
(computer rooms/labs) requiring close tolerance control of
temperature and humidity. The conditioned space should
be well insulated and include a vapor barrier. The installer
should ensure that the proper insulation rating is used
based on the design of the space that was the basis for the
system selected. The following table is a recommended
minimum R-value (thermal resistance) to ensure optimum
equipment operation.
STRUCTURE RVALUE
Ceiling R38
Wall R21
Floor R19
Door R5
The vapor barrier is the single most important requirement
for maintaining environmental control in the conditioned
space. The vapor barrier in the ceiling and walls can be
polyethylene film. Concrete walls and floors should be
painted with a rubber or plastic-based paint. Doors and
windows should be properly sealed and a door sweep used
to minimize leakage. Outside or fresh air should be kept to
a minimum (as it adds to the cooling, heating, dehumidifica-
tion and humidifying loads), while maintaining the require-
ment of the Indoor Air Quality (IAQ) standard. Lack of these
steps can cause erratic operation, unstable room control
and excessive maintenance costs.
2.3 Rigging
CeilAiR systems are designed to be kept in a horizontal po-
sition. The unit is shipped on a skid to facilitate moving prior
to installation. A suitable lifting device should be used to lift
the unit from the bottom. A weight table is provided for ref-
erence on the installation drawing. The unit should always
be stored indoors in a dry location prior to installation.
CAUTION
When movingthe unit, it must be kept horizontal and
level to prevent damage.
2.4 Mounting
CeilAiR OHS systems are designed for ceiling mounting in
a suspended ceiling grid (spot cooler) or above the sus-
pended ceiling for ducted systems. See Figure 6.
(BY OTHERS)
Figure 6. Typical Installation

10
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
NOTES
• Do not install the A/C system directly above
electronic equipmentthat may hinderservice-
ability.
• Equipment must be level to operate properly
2.4.1 Indoor Equipment
CeilAiR OHS systems have a frame and panel construction
for unit rigidity and full service accessibility while the unit
is mounted in place. The unit is lifted from underneath and
secured into place using all-thread rods passing through
rubber grommets or a 4 in. x 4 in. neoprene cork pad in the
mounting arms on the sides of the unit. Threaded rods, nuts
and washers (field supplied by others) must be secured so
they do not loosen. (See Figure 6 on page 9.)
Before mounting the unit, ensure the mounting structure is
able to support the weight of the equipment. Refer to the
weight table provided on the installation drawing. Secure
the unit via the predrilled mounting bolt holes with suitable
hardware for the application. An auxiliary drain pan is rec-
ommended and can be mounted directly under the cabinet
(only on ducted models; see Figure 9 on page 11).
2.4.2 Outdoor Equipment
Install remote condensers/condensing units in a secure
location where the unit cannot be tampered with and the
power service switch cannot be inadvertently turned off.
Locate the remote condenser/condensing unit where the
fan is not likely to draw dirt and debris into the coil fins.
There should be at least one equipment-width of clearance
around the condenser to ensure adequate airflow to the
coil. Secure the condenser/condensing unit so the system
will not move during operation. Refer to the installation
drawing for the non-charged system weight. It is recom-
mended that the remote condenser/condensing unit be
mounted with vibration mounts to reduce the amount of
vibration transmitted to the mounting surface.
2.4.3 Controls
NOTE
Thermostats and control sensors should not be
located near a doorway, supply air register or area
where they would be exposed to direct sunlight or
other external heat sources.
2.4.3.1 ATech Programmable Thermostats
Mount the thermostat upright on an inside wall within the
conditioned room at a location that best represents the
average room temperature. In most cases, the thermostat
should be located near the common return air grille. Mount
the thermostat at least 18 in. from an outside wall and ap-
proximately 5 ft above the floor. Follow the steps below for
mounting. Instructions for wiring the thermostat are found
in Section 2.7.2 on page 20.
1. Open the case with a flathead screwdriver. Place
blade in slot and gently pry forward at the numbered
locations shown in Figure 7.
Figure 7. ATech Controller Installation
2. Place the base temporarily over the wire hole opening
in the wall. Level the base and mark the screw loca-
tions through the two provided mounting slots.
CAUTION
Do not touch the temperature sensor on the bottom
left corner of the thermostat. The sensor can be
damaged if handled improperly.
3. If using the supplied anchors, drill two 3/16 in. holes
and tap in the wall anchors. If only the screws are being
used, drill two 3/32 in. holes.
4. Fasten the base to the wall using the supplied screws.
5. Connect wiring between the thermostat and equip-
ment. See the ATech wiring instructions in Section
2.7.2 on page 20.
6. Reinstall thermostat cover to base.
n
o
p
q

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
11
.75 in/19 mm
THICK
GASKET
90° / RIGHTANGLE IN/OUT SAME FACESTRAIGHT-THRU
SUPPLY
AIR OUTLET
Figure 8. Spot Cooler Grille
Figure 9. Ducted System Typical Air Patterns

12
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
2.4.3.2 Advanced STULZ E² Controller
If the optional STULZ E² controller is furnished, a separate
manual is included in the unit data package provided with
the unit. The controller user interface display may be field
mounted to a wall within the conditioned space or it may be
located outside the conditioned space if desired. Refer to
the supplemental instructions provided with the mounting
kit when mounting the controller display. When locating the
display panel, consider the length of wire to be used. As an
option, a 30 ft, 75 ft or 150 ft long cable may be provided
by STULZ.
2.4.4 Optional Equipment
NOTE
Do not mount any optional equipment on the A/C
unit’s access panels.
2.4.4.1 Condensate Pump (Field Installed)
If the unit was not purchased with the factory-installed con-
densate pump option, the shipped-loose condensate pump
should be mounted as near to the air conditioning system
as possible. The inlet hole in the pump must be belowthe
lowest part ofthe drain from the A/C unit. The pump has
two mounting supports so it can be hung on an adjacent
wall. Ensure that the pump is level for proper operation.
CAUTION
Always follow manufacturer’s instructions when in-
stalling afield-installed condensate pump. If manu-
facturer’s instructions were not provided with the
pump, contact STULZ product supportforthe pump
documentation. Do not installthe pump without first
reading the manufacturer’s instructions. Failure to
exactly follow manufacturer’s instructions may on
rare occasions result in serious damage tothe OHS
unit and the surrounding facility.
A P-trap must be installed between the pump and the unit.
The height of the trap must be a minimum of 2 in. to exceed
the total static pressure of the system and ensure proper
water drainage from the drain pan.
CAUTION
Properly size and vent the P-trap according to ap-
plicable codes and best practices.
2.4.4.2 Non-Fused Service Switch
The non-fused service switch may be used to disconnect
main power and isolate the unit during maintenance and
service. The switch has a lockable handle to lock power out
during maintenance periods. The switch is typically mount-
ed to the A/C cabinet; however, it may be shipped loose
for field installation. The case has a top keyhole mounting
slot and two holes in each bottom corner for mounting. The
hardware for mounting the switch is field supplied. Select
suitable fasteners for the intended mounting surface.
The non-fused service switch can be mounted near the
unit or in a central location. Non-fused service switches
are rated for either indoor or outdoor use. Ensure that the
proper type is used for your application.
NOTE
Referto the National Electrical Code and local codes
for the appropriate mounting location.
2.4.5 Remote Sensors
The remote temperature sensor or temperature/humidity
(T/H) sensor must be located so that it will properly sense
the temperature and/or humidity conditions to be con-
trolled. The sensor should not be mounted near a doorway
or an area where it would be exposed to direct sunlight.
When locating the sensor, consider the length of wire to be
used. As an option, a 75 ft or 150 ft cable may be provided
by STULZ. Refer to the applicable section that follows to
mount the sensor. For wiring details, referto Section 2.7.2
on page 20 and to the electrical drawing provided with
the unit.
2.4.5.1 Remote Temperature Sensor (ATech)
Figure 10. Temperature Sensor for ATech
NOTE
The remote temperature sensor has a maximum
range of 330 ft.
1. Install shielded or nonshielded two wire twisted cable
from the thermostat to the remote sensor location.
2. Open the sensor case by grasping the side and pulling
the two halves apart.

CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
13
3. Use the sub-base as a template to mark the mounting
hole locations on the mounting surface. Drill size for
the wall anchors is 1/4 in. Mount the sub-base over
the wires coming out of the wall using the two screws
and anchors provided. Do not use hex head screws.
4. Strip 1/4 in. of insulation from the two wires at the
remote sensor. Install the wires in the terminals. The
wires can be connected with either polarity. Seal the
hole in the wall around the cable to eliminate any draft
that might affect the sensor.
5. Make the wiring connections. Refer to section 2.7.6.4
on page 25 and to the wiring diagram supplied with
your unit.
6. Replace the sensor cover.
2.4.5.2 Remote Temperature/Humidity Sensor (E²)
OPENING FOR
CONTROL CABLE
WIRE TERMINALS
Figure 11. Temperature/Humidity Sensor for E2Con-
troller
1. Remove the cover from the base of the sensor by
squeezing it at the top and bottom.
CAUTION
Take care not to damagethe exposed temperature/
humidity sensor elements on the PC board when
the cover is removed. The sensor elements can be
damaged if handled improperly.
2. Place the base temporarily against the mounting
surface.
3. Level the base. Mark and drill mounting holes through
at least two of the available slotted holes. Also, mark
through the large opening in the base and drill a hole
into the mounting surface for a control cable to pass
through the back of the base.
4. Run a three-conductor shielded cable through the
opening in the base, then secure the base with screws,
ensuring the word TOP on the PC board is oriented
upward.
5. Route the sensor control cable up to the control termi-
nal block in the electric box and terminate the control
wire. Refer to section 2.7.6.5 on page 25 and to the
wiring diagram supplied with your unit.
6. Seal the hole in the wall behind the sensor.
7. Replace the cover plate on the base.
2.4.6 Humidistat/Dehumidistat (Used with
ATech1.1/1.2 Thermostat)
Mounting the humidistat and/or dehumidistat is performed
in the same manner as described in section 2.4.5.1. It
should be mounted to a wall within the conditioned room at
a location that best represents the average humidity of the
space. In most cases, the humidistat and/or dehumidistat
should be located near the common return air grille. Mount
the humidistat and dehumidistat at least 18 in. from an
outside wall and approximately 5 ft above the floor.
Controls may be installed either on a flush switch box or on
a surface switch box. Follow the steps below for mount-
ing. Instructions for wiring the unit are provided in Section
2.7.6.2 on page 24.
1. Pull dial knob off, loosen screw (located at bottom of
unit) and remove cover.
2. Make wiring connections according to the wiring dia-
gram provided with your unit.
3. Mount the base with the two #6 screws provided.
4. For external setpoint, reinstall cover, tighten screw, and
replace dial knob.
5. For internal setpoint:
a. Turn dial plate to desired setting and tighten dial
lock screw.
b. Break off dial shaft at undercut.
c. Remove insert from cover.
d. Remove protective backing from adhesive on the
blank insert provided and press firmly in place on
cover.
e. Reinstall cover assembly and tighten screw. (If
additional security is required an Allen screw and
wrench are provided.)
f. Remove protective cover from face of cover insert.

14
CEILAIR OHS SERIES INSTALLATION, OPERATION AND MAINTENANCE MANUAL
2.4.7 Spot Water Detector
The spot water detector is normally placed on the floor or in
a field-supplied auxiliary drain pan located beneath the
unit.
It may be attached using double sided tape or with the
mounting holes provided in the flanges
(one on each side). Once it’s in place,
loosen the screws provided on the
mounting legs to adjust the height of
the sensing probes. When water is
present, current will flow between the
two probes.
CAUTION
The probes must not touch the mounting surface.
Failure to adhere to this may result in improper op-
eration of equipment.
For wiring details, refer to Section 2.7.6.3 on page 25
and to the electrical drawing provided with the unit.
2.4.8 Cable Type Water Detector
CAUTION
Do not allow the cable water detector to contact
metal (frame orcondensate pan). It must be mounted
on the plastic stand-offs provided with the water
detector.
Lay the cable water detector across the surface where wa-
ter could collect. When
water is present, cur-
rent will flow between
the two wires. A two
conductor wire harness
is provided with a quick
connect fitting on the end. The harness mates to the fitting
on the water detector cable and connects it to the terminal
block inside the electric box.
2.5 Air Distribution Connection
2.5.1 Spot Cooler
For units that are not ducted (see Figure 9), the air condi-
tioner should be mounted above the ceiling grid, leaving
sufficient space for the air grilles to rest on the ceiling
T-bar.
NOTE
Placement of the grilles is important. The hinged
filter grille goes onthe return airside ofthe unit. The
3-way directional grille goes on the conditioned air
discharge side of the air conditioner. Gasketing is
factory-supplied for the air seal between the bot-
tom flange of the air conditioner and the grille. After
mounting the air conditioner, attach the gasket to
the bottom flange, then lower the air conditioner
until the gasket meets the grille, as shown in Figure
8 on page 11.
2.5.2 Ducted Systems
There are three basic configurations of airflow patterns:
90º/right angle, straight-through and in/out-same-face
(see Figure 9). When determining ducting requirements,
always consult your local and state codes. The duct system
should be designed to allow the air to move with as little
resistance as possible. Several factors determine ducting
material and size. These factors are predetermined, refer to
your ducting system schematic.
The connection of ducting to the unit is typically accom-
plished with a 1 in. duct flange. Supply air outlet and return
air inlet ducts will require a field-provided duct flange (refer
to the installation drawing provided with the unit). The con-
nection of ductwork to the unit may be made with either
pop rivets or self-tapping screws.
2.6 Piping Connections
2.6.1 Refrigerant
2.6.1.1 Self-Contained Systems
No refrigeration connections are required for self-con-
tained air, water or glycol-cooled systems (Models OHS-
012/040AS, OHS012/120C and OHS012/120-
W/G-( )).
2.6.1.2 Split Systems
Split air-cooled systems will require field refrigeration pip-
ing. All split systems are shipped with a dry nitrogen charge
of 100 psig. Systems utilizing a remote condenser will
require a copper liquid line and discharge line (see section
2.6.1.3). Systems utilizing a remote condensing unit (RCU)
will require a copper liquid line and suction line (see section
2.6.1.4).
All refrigeration piping should be installed with high tem-
perature brazed joints. Use standard refrigeration practices
for piping supports, leak testing, dehydration and charging