Trane OABE, OADE, OAKE, OANE Catalogue

Product Catalog

Horizon™ Outdoor Air Unit Water Source Heat Pump
For 100% Outdoor Air Applications

Models: OABE, OADE, OAKE, OANE

August 20 14

OAU-PRC003A-EN

Introduction

HIGH TURNDOWN INDIRECT GAS-FIRED BURNER

OPTIONAL RETURN-AIR

WITH EASY TO READ HUMAN INTERFACE

PLUS 2" MAXIMUM EXTERNAL CAPACITY

DAMPER

WITH STAINLESS STEEL HEAT EXCHANGER

MICROPROCESSOR BASED CONTROL

REHEAT COIL SEPARATED

FROM EVAPORATOR

FOR ERV, POWERED EXHAUST, AND

SECONDARY ELECTRIC HEAT OPTIONS

SLIDE IN FILTER FRAMES WITH

6" MAXIMUM INTERNAL CAPACITY

AVAILABLE AUXILIARY CABINET

2" SOLID DOUBLE WALL

WITH FOAM INSULATION

DIGITAL SCROLL

COMPRESSORS

DIRECT DRIVE PLENUM FAN WITH

SLIDE OUT SERVICE ACCESS

INTERLACED EVAPORATOR
COIL WITH STAINLESS STEEL

DRAIN PAN

The Horizon Outdoor Air Unit Water Source Heat Pump...

The T rane Horizon™ Outdoor Ai r Water Source Heat P ump for 100 percent outdoor air or dew point
design applications leads the industry in:

• Indoor Air Quality (IAQ) Features

• Moisture Management

• High Quality and Durability

• Advanced Controls

Copyright

Trademarks

Revision History

© 2014 Trane All rights reserved OAU-PRC003A-EN

This document and the information in it are the property of Trane, and may not be used or
reproduced in whole or in part without written permission. Trane reserves the right to revise this
publication at any time, and to make changes to its content without obligation to notify an y person
of such revision or change.

All trademarks referenced in this document are the trademarks of their respective owners.

OAU-PRC003A-EN (10 Aug 2014)

• First version of this literature

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Model Number Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Horizon Outdoor Air Unit Water Source Heat Pump . . . . . . . . . . . . . . . . . . . 5

Features and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

System Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Horizon OAU Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

OAU with Reheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

OAU Outdoor Air Control without Reheat . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Establishing Capacity Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Cooling & Dehumidification Selection Criteria . . . . . . . . . . . . . . . . . . . . . . . 17

Outdoor Airflow Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Air to Air Energy Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

The Horizon Outdoor Air Unit Water Source Heat Pump... . . . . . . . . . . . . 2

Model: OABE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Models: OADE, OAKE, OANE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Indoor Air Quality (IAQ) Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Energy Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

High Quality and Durability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Advanced Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Enhanced Serviceability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Standard Unit Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Standard Control Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Optional Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Outdoor Air Unit Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Dehumidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Cooling or Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Dehumidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Cooling or Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Evaporator Design Entering Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Evaporator Design Leaving Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Reheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Discharge Air Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Cooling Setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Unoccupied Space Humidity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Space Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Controlling the Total-Energy Wheel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Cross Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

OAU-PRC003A-EN 3

Condensate Drain Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Acoustical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Clearance Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Duct Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Controls Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Selection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Horizon OAU WSHP Selection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

General Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Unit Clearances, Curb Dimensions, and Dimensional Data . . . . . . . . . . . . . . . 34

OABE Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Curb Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

OADE Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Curb Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

OAKE Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Curb Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

OANE Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Curb Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Unit Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Unit Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Rigging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Mechanical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Horizon Outdoor Air Mechanical Specifications . . . . . . . . . . . . . . . . . . . . . . 58

Refrigeration and Dehumidification Systems . . . . . . . . . . . . . . . . . . . . . . 58

Electrical and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

OAU Filter Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

4 OAU-PRC003A-EN

Model Number Descriptions

Horizon Outdoor Air Unit Water Source Heat Pump

Model: OABE

Typical model number (example):

OABE036A4 -D1A1A0AB-G1CB0AC3AB-A11B102A0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839

Digit 1, 2 — Unit Type

OA = Outdoor Air

Digit 3 — Cabinet Size

B = 500–3000 CFM

Digit 4 — Major Design
Sequence

E = Heat Pump

Digit 5, 6, 7 — Normal Gross
Cooling Capacity (MBh)

000= No Cooling
036= 3 Tons High Efficiency
048= 4 Tons High Efficiency
060= 5 Tons High Efficiency
072= 6 Tons High Efficiency
084= 7 Tons High Efficiency
096= 8 Tons High Efficiency
108 = 9 Tons High Efficiency

Digit 8 — Minor Design
Sequence

A
B

Digit 9 — Voltage Selection

3 = 208-230/60/3
4 = 460/60/3
5 = 575/60/3

Digit 10 — Reserved for Future
Use

Digit 11 — Evaporator Type

B = DX 4-Row
C = DX 4-Row Interlaced
G = DX 4-Row with

MSP

®

Technology

Digit 12 — Hot Gas Reheat

0=No HGRH
1 = Fin and Tube Modulating
2 = Fin and Tube On/Off
3 = Microchannel Modulating
4 = Microchannel On/Off

Digit 13 — Compressor

B = Digital Scroll—1st Circuit Only
C = Digital Scroll—1
D = Variable Speed Scroll—1

E = Variable Speed Scroll—1

Circuit Only

nd

2

Circuit

st

and 2nd Circuit

st

st

and

Digit 14 — Condenser

3 = Water-Cooled DX Condenser

Copper/Steel

8 = Water-Cooled DX Condenser

Copper/Nickel

Digit 15 — Refrigerant Capacity
Control

0 = No RCC Valve

Digit 16 — Indoor Fan Motor
(IFM)

0 = ECM w/Backward Curved

Plenum Fan

4 = Special Motor Option

Digit 17 — Indoor Fan Wheel

A = 355
B = 450

Digit 18 — Indoor Fan Motor
(hp)

A = 1 kW–1.5 hp
B = 2 kW–2.5 hp
C = 3 kW–4.0 hp

Digit 19 — Reserved for Future
Use

Digit 20 — Heater Type
(PRI/SEC)

0 = No Auxiliary Heat
A = Indirect-Fired (IF)
B = Direct-Fired (DF)
C = Electric—4-Stage
D = Electric—SCR Modulating
E = Dual Fuel (PRI-IF/SEC-DF)
F = Dual Fuel (PRI-ELEC/SEC-DF)
G = Dual Fuel (PRI-IF/SEC-ELEC)
H = Dual Fuel (PRI-ELEC/SEC-ELEC)
J=Hot Water
K=Steam

Digit 21 — Primary Fuel Type

0 = No Auxiliary Heat
1=Natural Gas
2=Propane
3 = Electric—Open Coil
4 = Electric—Sheathed Coil
5=Hot Water
6=Steam

Digit 22 — Heater Capacity—
Primary Heat Source

IF ELEC

0 = No Auxiliary

Heat
A = 50 MBh 5 kW
B = 75 MBh 10 kW
C = 100 MBh 15 kW
D = 125 MBh 20 kW
E = 150 MBh 24 kW
F = 200 MBh 28 kW
G = 32 kW
H = 40 kW
J = 48 kW
X = Special Heater Option

No Auxiliary
Heat

Digit 23 — Heat Capacity—
Secondary Heat Source

ELEC DF

0 = No Heat/No Secondary Heat
A = 5 kW 300 MBh
B=10 kW
C=15 kW
D = 20 kW
E = 24 kW
F = 28 kW
G = 32 kW
H = 40 kW
J = 48 kW

Digit 24 — Corrosive
Environment Package

0 = No Corrosive Package
1 = S/S Cabinet, Basepan,

2 = S/S Cabinet, Basepan
3 = S/S Basepan, Eco-Coated Coils
4 = S/S Coil Casing
5 = S/S Interior Casing
6 = Eco-Coated Coils
7 = S/S Coil Casing with

8 = Copper/Copper Evap, HGRH
Coils

Eco-Coated Coils

Eco-Coated Coils

OAU-PRC003A-EN 5

Model Number Descriptions

OABE Units

Digit 25, 26 — Unit Controls

00 = Non DDC—Electromechanical
AA = Trane—Discharge Air Control

AB = Trane—Space Control w/LON
AC = Trane—Discharge Air Control
AD = Trane—Space Control
AF = Trane—Discharge Air Control
AG = Trane—Space Control
AI = Trane—Discharge Air Control
AJ = Trane—Space Control
AK = Trane—Multi-Zone VAV Control
AL = Trane—Multi-Zone VAV Control
AM = Trane—Multi-Zone VAV Control
AN = Trane—Multi-Zone VAV Control
AO = Trane—Single-Zone VAV Control
AP = Trane—Single-Zone V AV Control
AQ = Trane—Single-Zone VAV Control
AR = Trane—Single-Zone VAV Control

w/LON Read-Write w/Display
Read-Write w/Display
w/BACnet
w/BACnet (No Display)
w/BACnet w/Display
w/BACnet w/Display
w/LON Read-Write (No Display)
w/LON Read-Write (No Display)
w/LON Read-Write w/Display
w/BACnet w/Display
w/LON Read-Write (No Display)
w/BACnet (No Display)
w/LON Read-Write w/Display
w/BACnet w/Display
w/LON Read-Write (No Display)
w/BACnet (No Display)

®

(No Display)

Digit 27 — Po wered Exhaust Fan
Motor (PFM) and Exhaust
Dampers

0 = No Powered Exhaust
5 = Special Motor Option
6 = ECM w/Backward Curved

7 = ECM w/Backward Curved

8 = ECM w/Backward Curved

9 = Barometric Relief Dampers

Plenum Fan
Plenum Fan and Barometric

Relief Damper
Plenum Fan and Isolation

Dampers w/End Switch
(No PFM)

Digit 28 — Po wered Exhaust Fan
Wheel

0 = No Powered Exhaust
A = 355

Digit 29 — Po wered Exhaust Fan
Motor HP

0 = No Powered Exhaust
A = 1 kW–1.5 hp
B = 2 kW–2.5 hp
C = 3 kW–4.0 hp

DIGIT 30 — Reserved for Future
Use

Digit 31 — ERV (Requires
Powered Exhaust)

0=No ERV
A = ERV—Composite Construction

w/Bypass

B = ERV—Composite Construction

with Frost Protection w/VFD

C = ERV—Aluminum Construction

w/Bypass

D = ERV—Aluminum Construction

with Frost Protection w/VFD

Digit 32 — ERV Size

0=No ERV
1=3014
2 = 3622

Digit 33 — Damper Options

0 = 100% OA 2-Position Damper
1 = 100% OA 2-Position Damper

w/RA 2-Position Damper

2 = Modulating OA and RA Dampers

w/Economizer

Digit 34 — Filtration Options

A = No Filters
B = MERV-8, 30%
C = MERV-13, 80%
D = MERV-14, 95%
E = MERV-8 30%, MERV-13 80%
F = MERV-8 30%, MERV-14 95%
G = MERV-8, 30%, and UVC
H = MERV-13, 80%, with UVC
J = MERV-14, 95%, with UVC
K = MERV-8 30%, MERV-13 80%,

and UVC

L = MERV-8 30%, MERV-14 95%,

and UVC
M = MERV-8 30%, and TCACS
N = MERV-13 80%, and TCACS
P = MERV-14 95%, and TCACS
Q = MERV-8 30%, MERV-13 80%,

and TCACS
R = MERV-8 30%, MERV-14 95%,

and TCACS
X = Special Filter Options

Digit 35 — Smoke Detector—
Factory Installed

0 = No Smoke Detector
1 = Supply Smoke Detector
2 = Return Smoke Detector
3 = Supply and Return Smoke

Detectors

Digit 36 — Electrical Options

0 = Terminal Block
A = Non-Fused Disconnect
B = Fused Disconnect Switch
C = Non-Fused Disconnect

w/Convenience Outlet

D = Fused Disconnect Switch

w/Convenience Outlet
E = Dual Point Power
F = Dual Point Power

w/Convenience Outlet
G = 65 SCCR Electrical Rating

w/Non-Fused Disconnect
H = 65 SCCR Electrical Rating

w/Fused Disconnect
J = 65 KAIC Electrical Rating

w/Non-Fused Disconnect
K = 65 KAIC Electrical Rating

w/Fused Disconnect

Digit 37 — Air Flow Monitoring

0 = No Airflow Monitoring
1 = Airflow Monitoring—IFM

Piezo Ring
2 = Airflow Monitoring—PE

Piezo Ring
3 = Airflow Monitoring—Outdoor Air

with Display and IFM

w/Piezo Ring
4 = Airflow Monitoring—IFM

Piezo Ring and PE Piezo Ring
5 = Airflow Monitoring—Outdoor Air

Monitoring w/Display Supply Air

and Exhaust Air w/Piezo Rings

Digit 38 — Accessories

0 = No Options
B = LED Service Light

Digit 39 — Altitude

0 = Sea Level to 1,000 feet
1 = 1,001 to 2,000 feet
2 = 2,001 to 3,000 feet
3 = 3,001 to 4,000 feet
4 = 4,001 to 5,000 feet
5 = 5,001 to 6,000 feet
6 = 6,001 to 7,000 feet
7 = Above 7,000 feet

6 OAU-PRC003A-EN

Model Number Descriptions

Models: OADE, OAKE, OANE

Typical model number (example):

OAKE300A4-D1A1A0GM-G1KB0AC3CJ -A41B102A0

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839

Digit 1, 2 — Unit Type

OA = Outdoor Air

Digit 3 — Cabinet Size

D = 625–4,000 cfm
K = 1,500–9,000 cfm
N = 3,750–13,500 cfm

Digit 4 — Major Design
Sequence

E = Heat Pump

Digit 5, 6, 7 — Normal Gross
Cooling Capacity (MBh)

000= No Cooling
060= 5 Tons High Efficiency
072= 6 Tons High Efficiency
084= 7 Tons High Efficiency
096= 8 Tons High Efficiency
120 = 10 Tons High Efficiency
144 = 12 Tons High Efficiency
180 = 15 Tons High Efficiency
210 = 17 Tons High Efficiency
240= 20 Tons High Efficiency
264= 22 Tons High Efficiency
300 = 25 Tons High Efficiency
360= 30 Tons High Efficiency
420= 35 Tons High Efficiency
480= 40 Tons High Efficiency
540= 45 Tons High Efficiency
600 = 50 Tons High Efficiency
648= 54 Tons High Efficiency

Digit 8 — Minor Design
Sequence

A
B

Digit 9 — Voltage Selection

3 = 208-230/60/3
4 = 460/60/3
5 = 575/60/3

Digit 10 — Reserved for Future
Use

Digit 11 — Evaporator Type

B = DX 4-Row
C = DX 4-Row Interlaced

Digit 12 — Hot Gas Reheat

0=No HGRH
1 = Fin and Tube Modulating
2 = Fin and Tube On/Off
3 = Microchannel Modulating
4 = Microchannel On/Off

Digit 13 — Compressor

B = Digital Scroll—1st Circuit Only
C = Digital Scroll—1
D = Variable Speed Scroll—1

E = Variable Speed Scroll—1

Circuit Only

nd

2

Circuit

st

and 2nd Circuit

st

st

and

Digit 14 — Condenser

3 = Water-Cooled DX Condenser
8 = Water-Cooled DX Condenser

Copper/Steel
Copper/Nickel

Digit 15 — Refrigerant Capacity
Control

0 = No RCC Valve

Digit 16 — Indoor Fan Motor
(IFM)

0 = Direct Drive w/VFD
1 = Direct Drive (VFD by Others)
4 = Direct Drive w/Shaft

5 = Special Motor Option

Grounding Ring w/VFD

Digit 17 — Indoor Fan Wheel

A=122
B = 122.6
C=150
D = 150.6
E=165
F = 165.6
G=182
H = 182.6
J=200
K = 200.6
L = 182 X 2
M = 182.6 X 2

Digit 18 — Indoor Fan Motor HP

A = 1/2 hp—1800 rpm
B = 1/2 hp—3600 rpm
C = 3/4 hp—1800 rpm
D = 3/4 hp—3600 rpm
E = 1 hp—1800 rpm
F = 1 hp—3600 rpm
G = 1.5 hp—1800 rpm
H = 1.5 hp—3600 rpm
J = 2 hp—1800 rpm
K = 2 hp—3600 rpm
L = 3 hp—1800 rpm
M = 3 hp—3600 rpm
N = 5 hp—1800 rpm
P = 5 hp—3600 rpm
R = 7.5 hp—1800 rpm
S = 7.5 hp—3600 rpm
T = 10 hp—1800 rpm
U = 10 hp—3600 rpm
V = 15 hp—1800 rpm
W = 15 hp—3600 rpm

Digit 19 — Reserved for Future
Use

Digit 20 — Heat Type (PRI/SEC)

0 = No Auxiliary Heat
A = Indirect-Fired (IF)
B = Direct-Fired (DF)
C = Electric—4-Stage
D = Electric—SCR Modulating
E = Dual Fuel (PRI-IF/SEC-DF)
F = Dual Fuel (PRI-ELEC/SEC-DF)
G = Dual Fuel (PRI-IF/SEC-ELEC)
H = Dual Fuel (PRI-ELEC/SEC-ELEC)
J=Hot Water
K = Steam

Digit 21 — Primary Fuel Type

0 = No Auxiliary Heat
1=Natural Gas
2=Propane
3 = Electric—Open Coil
4 = Electric—Sheathed Coil
5=Hot Water
6 = Steam

OAU-PRC003A-EN 7

Model Number Descriptions

OADE, OAKE, OANE Units

Digit 22 — Heat Capacity—
Primary Heat Source

IF ELEC

0 = No Auxiliary

Heat
A = 50 MBh 10 kW
B = 75 MBh 20 kW
C = 100 MBh 24 kW
D = 125 MBh 28 kW
E = 150 MBh 32 kW
F = 200 MBh 40 kW
G = 250 MBh 48 kW
H = 300 MBh 60 kW
J = 350 MBh 68 kW
K = 400 MBh 79 kW
L = 500 MBh 99 kW
M = 600 MBh 111 kW
N = 700 MBh 119 kW
P = 800 MBh 139 kW
R = 1000 MBh 159 kW
S = 179 kW
T = 199 kW
U = 215 kW
X = Special Heater Option

No Auxiliary
Heat

Digit 23 — Heat Capacity—
Secondary Heat Source

IF ELEC DF

0 = No Heat/No Secondary Heat
A = 50 MBh 10 kW 300 MBh
B = 75 MBh 20 kW 600 MBh
C = 100 MBh 24 kW 900 MBh
D = 125 MBh 28 kW 1200 MBh
E = 150 MBh 32 kW
F = 200 MBh 40 kW
G = 250 MBh 48 kW
H = 300 MBh 60 kW
J = 350 MBh 68 kW
K = 400 MBh 79 kW
L = 500 MBh 99 kW
M = 600 MBh 111 kW
N = 700 MBh 119 kW
P = 800 MBh 139 kW
R = 1000 MBh 159 kW
S = 179 kW
T = 199 kW
U = 215 kW

Digit 24 — Corrosive
Environment Package

0 = No Corrosive Package
1 = S/S Cabinet, Basepan,

2 = S/S Cabinet, Basepan
3 = S/S Basepan, Eco-Coated Coils
4 = S/S Coil Casing
5 = S/S Interior Casing
6 = Eco-Coated Coils
7 = S/S Coil Casing with

8 = Copper/Copper Evap, HGRH
Coils

Eco-Coated Coils

Eco-Coated Coils

Digit 25, 26 — Unit Controls

00 = Non DDC—Electromechanical
AA = Trane—Discharge Air Control

AB = Trane—Space Control
AC = Trane—Discharge Air Control
AD = Trane—Space Control
AF = Trane—Discharge Air Control
AG = Trane—Space Control
AI = Trane—Discharge Air Control
AJ = Trane—Space Control
AK = Trane—Multi-Zone VAV Control
AL = Trane—Multi-Zone VAV Control
AM= Trane—Multi-Zone VAV Control
AN = Trane—Multi-Zone VAV Control
AO = Trane—Single-Zone VAV Control
AP = Trane—Single-Zone V AV Control
AQ = Trane—Single-Zone VAV Control
AR = Trane—Single-Zone VAV Control

w/LON Read-Write w/Display
w/LON Read-Write w/Display
w/BACnet
w/BACnet (No Display)
w/BACnet w/Display
w/BACnet w/Display
w/LON Read-Write (No Display)
w/LON Read-Write (No Display)
w/LON Read-Write w/ Display
w/BACnet w/Display
w/LON Read-Write (No Display)
w/BACnet (No Display)
w/Lon Read-Write w/Display
w/BACnet w/Display
w/LON Read-Write (No Display)
w/BACnet (No Display)

®

(No Display)

Digit 27 — Pow ered Exhaust Fan
Motor (PFM) and Exhaust
Dampers

0 = No Powered Exhaust
1 = Direct Drive w/VFD and

2 = Direct Drive (VFD by Others)
3 = Belt Drive
4 = Belt Drive w/VFD
5 = Special Motor Option
6 = Direct Drive w/VFD and

7 = Direct Drive w/VFD and
8 = Barometric Relief Dampers

Gravity Dampers

Barometric Relief Damper
Isolation Dampers w/End Switch
(NO PFM)

Digit 28 — Pow ered Exhaust Fan
Wheel

0 = No Powered Exhaust
A=122
B = 122.6
C=150
D = 150.6
E=165
F = 165.6
G=182
H = 182.6
J=200
K = 200.6
L = 182 X 2
M = 182.6 X 2

Digit 29 — Pow ered Exhaust Fan
Motor (hp)

0 = No Powered Exhaust
A = 1/2 hp—1800 rpm
B = 1/2 hp—3600 rpm
C = 3/4 hp—1800 rpm
D = 3/4 hp—3600 rpm
E = 1 hp—1800 rpm
F = 1 hp—3600 rpm
G = 1.5 hp—1800 rpm
H = 1.5 hp—3600 rpm
J = 2 hp—1800 rpm
K = 2 hp—3600 rpm
L = 3 hp—1800 rpm
M = 3 hp—3600 rpm
N = 5 hp—1800 rpm
P = 5 hp—3600 rpm
R = 7.5 hp—1800 rpm
S = 7.5 hp—3600 rpm
T = 10 hp—1800 rpm
U = 10 hp—3600 rpm
V = 15 hp—1800 rpm
W = 15 hp—3600 rpm

Digit 30 — Reserved for Future
Use

Digit 31 — ERV (Requires
Powered Exhaust)

0=No ERV
A = ERV—Composite Construction
B = ERV—Composite Construction

with Frost Protection w/VFD

C = ERV—Composite Construction

with Bypass

D = ERV—Composite Construction

with Frost Protection and Bypass
E = ERV—Aluminum Construction
F = ERV—Aluminum Construction

with Frost Protection w/VFD
G = ERV—Aluminum Construction

with Bypass
H = ERV—Aluminum Construction

with Frost Protection and Bypass

8 OAU-PRC003A-EN

Model Number Descriptions

OADE, OAKE, OANE Units

Digit 32 — ERV Size

0=No ERV
1=3014
2 = 3622
3 = 4136
4 = 4634
5 = 5856
6 = 6488
7 = 6876
8=74122

Digit 33 — Damper Options

0 = 100% OA 2-Position Damper
1 = 100% OA 2-Position Damper

w/RA 2-Position Damper

2 = Modulating OA and RA Da mpers

w/Economizer

Digit 34 — Filtration Options

A = Aluminum Mesh Intake Filters

(ALM)
B = MERV-8,30%, and ALM
C = MERV-13, 80%, and ALM
D = MERV-14, 95%, and ALM
E = MERV-8 30%, MERV-13 80%, and

ALM
F = MERV-8 30%, MERV-14 95%, and

ALM
G = MERV-8, 30%, and ALM, with

UVC
H = MERV-13, 80%, and ALM, with

UVC
J = MERV-14, 95%, and ALM, with

UVC
K = MERV-8 30%, MERV-13 80%,

ALM, and UVC
L = MERV-8 30%, MERV-14 95%,

ALM, and UVC
M = MERV-8 30%, ALM, and TCACS
N = MERV-13 80%, ALM, and TCACS
P = MERV-14 95%, ALM, and TCACS
Q = MERV-8 30%, MERV-13 80%,

ALM, and TCACS
R = MERV-8 30%, MERV-14 95%,

ALM, and TCACS
X = Special Filter Options

Digit 35 — Smoke Detector—
Factory Installed

0=No Smoke Detector
1 = Supply Smoke Detector
2 = Return Smoke Detector
3 = Supply and Return Smoke

Detector

Digit 36 — Electrical Options

0 = Non-Fused Disconnect
A = Fused Disconnect Switch
B = Non-Fused Disconnect

w/Convenience Outlet

C = Fused Disconnect Switch

w/Convenience Outlet

D = Dual Point Power

w/Convenience Outlet

F = 65 SCCR Electrical Rating

w/Non-Fused Disconnect

G = 65 SCCR Electrical Rating

w/Fused Disconnect

H = 65 KAIC Electrical Rating

w/Non-Fused Disconnect

J = 65 KAIC Electrical Rating

w/Fused Disconnect

Digit 37 — Air Flow Monitoring

0 = No Airflow Monitoring
1 = Airflow Monitoring—IFM

Piezo Ring

2 = Airflow Monitoring—PE

Piezo Ring

3 = Airflow Monitoring—Outdoor Air

with Display and IFM
w/Piezo Ring

4 = Airflow Monitoring—IFM

Piezo Ring and PE Piezo Ring

5 = Airflow Monitoring—Outdoor Air

Monitoring w/ Display Supply
Air and Exhaust Air
w/Piezo Rings

Digit 38 — Accessories

0 = No Options
B = LED Service Light

Digit 39 — Altitude

0 = Sea Level to 1,000 feet
1 = 1,001 to 2,000 feet
2 = 2,001 to 3,000 feet
3 = 3,001 to 4,000 feet
4 = 4,001 to 5,000 feet
5 = 5,001 to 6,000 feet
6 = 6,001 to 7,000 feet
7 = Above 7,000 feet

OAU-PRC003A-EN 9

Features and Benefits

We designed the Horizon™ Outdoor Air Unit based on customer requirements from across the
country. Thorough analysis of the performance requirements resulted in a robust design with the
ability to effectively operate over an expansive performance envelope required for the year -round
treatment of outdoor air.

Also, we took into account today’s HVAC market issues, such as indoor air quality (IAQ). We
equipped the Horizon Outdoor Air Unit to meet your ventilation needs—in direct response to the
ventilation and humidity control requirements of ASHRAE standard 62.1.

Trane’s Horizon Outdoor Air Unit leads the industry in the key areas of:

• indoor air quality (IAQ)

• energy efficiency

• high quality and durability

• advanced, integrated controls

• flexibility (including indoor installation)

• enhanced serviceability

Indoor Air Quality (IAQ) Features

• Stainless steel drain pan sloped in two directions to ensure proper drainage and reduce the
potential for microbial growth.

• Double-wall foamed panel construction throughout the indoor section of unit to provide, non­porous, cleanable interior surfaces.

• Inlet hood with moisture eliminators.

• High efficiency throwaway filter option with standard 2-, 4-, or 6-inch adjustable filter rack.

• Piezometer airflow measurement option.

• Easy filter access encourages frequent changing.

• Refrigerant hot gas reheat for low dewpoint supply air for superior humidity control.

• Capable of providing low dew point supply air for superior humidity control.

Energy Efficiency

• Total energy wheel option for recovered energy from centralized building exhaust.

• Optional modulating recovered refrigerant reheat for unit supply air.

High Quality and Durability

• Robust unit construction with 2-inch double-wall panels and reversible, hinged access doors.

• High quality, long-lasting latches and hinges for all access doors.

• Protective standard prepainted finish on cabinet exterior with optional corrosion inhibiting
coatings available for the unit exterior, interior and coils.

Advanced Controls

• All controls are factory-engineered, mounted, configured and tested to minimize field startup
time.

• UC600 microprocessor control with easy-to-read human interface and display for monitoring,
setting, editing, and controlling.

• Human interface with touch-pad screen for monitoring, setting, editing and controlling.

• Capable of supply-air control or zone control of both temperature and relative humidity

• Occupied and unoccupied control sequences.

• Optional remote human interface for ease of control access without going outdoors.

• Optional LonTalk
building management system or other control systems that support LonTalk.

®

communications interface communication link with a Tracer Summit™

10 OAU-PRC003A-EN

Flexibility

Features and Benefits

• Numerous heater options and temperature rise capabilities available.

• Multiple roof curb options (1- or 2-inch vibration isolation, horizontal discharge, multiple
heights)

• Dual fuel (indirect/electric) option

•Custom colors

Figure 1. Condenser side view of the Trane Horizon™ Outdoor Air Unit Water Source Heat

Pump

Enhanced Serviceability

• Hinged access doors for ease of maintenance and service

• Easy-open door latches

• Slide out access direct-drive plenum fan

• Optional slide out, self-cleaning total-energy wheel

• Sight glass for each refrigeration circuit

• Optional control display

• High voltage cover

Standard Unit Features

• Multiple cabinet sizes with airflow range from 500 to 13,500 cfm

• Two-inch double-wall, R-13 construction with heavy gauge galvanized metal skin

• Outdoor air inlet hood

• Prepainted exterior finish

• Water-cooled DX refrigeration system

• Completely factory-piped and leak-tested refrigeration system

• Stainless steel drain pans sloped in two planes

• Digital scroll compressors

OAU-PRC003A-EN 11

Features and Benefits

• Single-point power connections for units with optional total-energy wheel, powered exhaust,
and electric heat

• Filter rack adjustable for 2-, 4-, or 6-inch filters

• Factory-assembled inlet hood with 2-inch mist eliminators (OAD, OAK, OAN)

• Non-fused disconnect switc h

• Type 439 stainless steel heat exchanger

• Low leak parallel blade outdoor air damper with edge seals

• High-efficiency fan motors

Standard Control Features

• Fully integrated, factory-installed and commissioned microelectronic controls

• Supply airflow proving

• Emergency stop

• Occupied/unoccupied control modes

• High turn-down (up to 20:1) modulating indirect gas-fired heat

• Clogged filter switch

• Low ambient control down to 0°F

Optional Features

• Modulating electric heat

•Hot water coils

• Steam heat (future)

• Low leak parallel blade return air damper with edge seals

• Modulating damper control systems

• Pleated media filters (2-inch MERV-8, 2-inch MERV-13, 4-inch MERV-14, or a combination
2-inch/4-inch filter)

• 24 V electrostatic filters

• 120 V UVC downstream of evaporator coil

• High static fan

• Adjustable powered exhaust

• Exhaust dampers (gravity, barometric relief, and 2-position isolation)

• Fused disconnect switch

• Factory-installed smoke detectors (supply and/or return)

• Integral total-energy wheel

• Protective coatings for the unit and/or coils

• Remote human interface

• Factory or field-wired convenience outlet

• LED service lights

• Direct drive BI airfoil plenum fan

• Factory-installed variable frequency drive (VFD)

• Unit mounted human interface panel

12 OAU-PRC003A-EN

Application Considerations

Overview

Outdoor Air Unit Functions

The Horizon™ Outdoor Air Unit (OAU) provides conditioned outdoor air suitable for mec hanical
ventilation or make-up air. The OAU conditions outdoor air as necessary to meet system
performance requirements by ventilation with filtration, cooling, dehumidification, and/or heating.
The OAU may deliver ventilation air in a number of ways. Refer to “System Configurations,” p. 13
and Figure 5, p. 15, Figure 6, p. 15, and Figure 8, p. 16 for more information.

• V entilation with Filtration

• Cooling

• Dehumidification

•Heating

System Configurations

Dedicated outdoor air systems can deliver conditioned outdoor air in one of the following ways:

1. Conditioned outdoor air supplied directly to each occupied space, with the local terminal unit
controlling the space dry-bulb temperature. Refer to Figure 2, p. 13.

2. Conditioned outdoor air supplied directly to local terminal units, or return ducts of lo cal RTUs,
which deliver a mixture of the conditioned outdoor air and (conditioned) recirculated air to the
space. Refer to Figure 3, p. 14.

3. Conditioned outdoor air supplied directly to a single space to control the space temperature
and humidity. F o r example, this application will provide temperature and humidity control of
ventilated spaces, such as commercial kitchens or laboratories.

Figure 2. Direct discharge to conditioned space

OAU-PRC003A-EN 13

Application Considerations

Main Condenser

Reheat Coil

Main Evaporator

Expansion Valves

Compressors

Indoor Fan

Figure 3. Indirect discharge to fan-coil units

Horizon OAU Operation

The Horizon™ OAU can use either DX cooling, condenser reheat, electric or gas heat to condition
outdoor air. The unit controls modulate cooling and heating capacity, reducing the supply air
temperature swings associated with staged heating and cooling.

OAU with Reheat

Dehumidification

14 OAU-PRC003A-EN

Figure 4, p. 14 shows the OAU system with a DX refrigerant circuit design using reheat.

Figure 4. Refrigeration system diagram with reheat

Consider Figure 5, p. 15. If the outdoor air dew point is above the dehumidification setpoint (or in
the case of zone control, the zone RH is above the RH setpoint), the OAU will:

• cool the outdoor air to remove required moisture and

• reheat to meet the discharge temperature setpoint.

Application Considerations

h1

h3

h4

h2

Dry Bulb Temperature

Dewpoint Temperature

Wet Bulb Temperature

t3

t4

heating

t1

t2

cooling

At h1, 100 percent outdoor air enters the O AU . Th e O A U filters, cools, and dehumidifies the air as
it moves through the evaporator coil. Air leaves the evaporator coil saturated at the preset dew
point condition (h3) and is reheated by the reheat coil to the pre-set reheat temperature setpoint
(h4). The reheat coil transfers energy to the airstream. A liquid solenoid valve effectively modulates
the reheat capacity. The outdoor condenser rejects surplus heat. The reheat circuit is first on and
last off, so reheat energy is available at full and part load conditions. Since both the dew point
setpoint and discharge temperature setpoint are fully adjustable, the desired supply air conditions
are maintained at all load conditions.

Figure 5. Psychrometric chart with dehumidification and reheat

Cooling or Heating

OAU Outdoor Air Control without Reheat

OAU-PRC003A-EN 15

Consider Figure 6, p. 15. If the outdoor air dew point or zone RH is equal to or below the
dehumidification setpoint, the O AU will heat or cool the outdoor air to separate cooling or heating
setpoints. At t1 or t3, 100 percent outdoor air enters the OA U . The O A U filters, and cools or heats
the air as it is drawn through the evaporator and heating section. The air leaves the OAU at the
cooling or heating discharge setpoint (t2 or t4).

Figure 6. Psychrometric chart with cooling or heating only

Figure 7, p. 16 shows the Horizon™ OAU DX system, using a refrigerant circuit design without

reheat.

Note: Space control not available without reheat.

Application Considerations

Main Condenser

Main Evaporator

Expansion Valves

Compressors

Indoor Fan

Dry Bulb Temperature

Dewpoint Temperature

Wet Bulb Temperature

Dehumidification

h1

h2

h3

Figure 7. Refrigeration system diagram without reheat

Dehumidification

Cooling or Heating

Consider Figure 8, p. 16. If the outdoor air dew point is above the dehumidification setpoint, the
OA U will dehumidify the outdoor air. 100 percent outdoor air enters the OAU (h1). The unit filters,
cools and dehumidifies the air as it is drawn through the evaporator coils. Air leaves the evaporator
coils saturated at a preset dew point setpoint (h3) . Since the dew point setpoint is fully adjustable,
the desired dew point condition is maintained at all load conditions.

Figure 8. Psychrometric chart with dehumidification, no reheat

Consider Figure 9, p. 17. If the outdoor air dew point is below the dehumidification setpoint, the
OAU will heat or cool the outdoor air to separate cooling or heating setpoints. 1 00 percent outdoor
air enters the OAU (t1 or t3). The unit filters and cools or heats the air as it is drawn through the
evaporators and heating section. The air leaves the OAU at the cooling or heating setpoint.

16 OAU-PRC003A-EN

Figure 9. Psychrometric chart with cooling and heating only

Dry Bulb Temperature

Dewpoint Temperature

Wet Bulb Temperature

t3

t4

heating

t1

t2

cooling

Establishing Capacity Requirements

Determining the OAU capacity requirements requires careful thought. Light Commercial
equipment is typically selected based on design sensible conditions. Since latent loads drive the
need for the OAU, base the selection on design latent conditions.

Application Considerations

Cooling & Dehumidification Selection Criteria

Evaporator Design Entering Conditions

Evaporator Design Leaving Conditions

OAU-PRC003A-EN 17

For many climates the peak outdoor air enthalpy occurs at a time when the outdoor dry-bulb
temperature is not the highest. Refer to the ch apter on climatic design information in the A SHRAE
Handbook of Fundamentals. The cooling and dehumidification design condition data is provided
three ways:

1. Design dry-bulb temperature with mean coincident wet bulb temperature

2. Design wet-bulb temperature with mean coincident dry-bulb temperature

3. Design dew point temperature with mean coincident dry-bulb temperature

The design wet-bulb condition typically represents a significantly higher ou tdoor air enthalpy than
the design dry-bulb condition. Use the condition that represents the highest enthalpy as the
entering evaporator selection condition.

Due to the uncertainty of the local terminal unit’s latent capacity at part load, it is usually most
straightforward to size the OAU to handle the entire latent load on the system, both indoor and
outdoor. With this design approach, the terminal units may do some latent cooling
(dehumidification) during periods of higher sensible load. At these times, the space will run slightly
drier than the design RH limit. This is why it makes sense to select the OAU to limit the space RH
to a maximum allowable level for those conditions when the terminal units are pro viding no space
latent cooling, such as 60 percent RH. Using lower humidity limits may result in an unnecessary
increase in system operating energy use.

Use Table 1, p. 18, Table 2, p. 18, and Table 3, p. 19 to identify the appropriate supply air dew point
for specific design conditions. Fo r a more detailed discussion on determining the selection criteria
of a OA U, refer to SYS-APG00 1-EN (Application Guide: Designing Dedicated Outdoor -Air Systems)
or SYS-APM004-EN (Applications Engineering Manual: Dehumidific ati on in HVAC Systems).

Application Considerations

Reheat

Table 1. Supply air dew point temperature, 75°F at 60 percent RH space limit

Latent Load
Btu/h per Person

100 54.6 56.6 57.5 58.1 58.4 58.7 58.9 59.0 59.2 59.2 59.3
120 53.3 55.8 57.0 57.6 58.1 58.4 58.6 58.8 58.9 59.1 59.2
140 52.0 55.0 56.4 57.2 57.7 58.1 58.3 58.6 58.7 58.9 59.0
160 50.6 54.2 55.8 56.7 57.3 57.8 58.1 58.3 58.5 58.7 58.8
180 49.2 53.3 55.2 56.3 57.0 57.4 57.8 58.1 58.3 58.5 58.6
200 47.7 52.5 54.6 55.8 56.6 57.1 57.5 57.8 58.1 58.3 58.4
220 46.1 51.6 54.0 55.3 56.2 56.8 57.2 57.6 57.9 58.1 58.3
240 — 50.6 53.3 54.8 55.8 56.5 57.0 57.3 57.6 57.9 58.1
260 — 49.7 52.7 54.3 55.4 56.1 56.7 57.1 57.4 57.7 57.9
280 — 48.7 52.0 53.8 55.0 55.8 56.4 56.8 57.2 57.5 57.7
300 — 47.7 51.3 53.3 54.6 55.5 56.1 56.6 57.0 57.3 57.5
320 — 46.6 50.6 52.8 54.2 55.1 55.8 56.3 56.7 57.1 57.3
340 — 45.5 49.9 52.3 53.8 54.8 55.5 56.1 56.5 56.8 57.1
360 — — 49.251.753.354.455.255.856.356.657.0
380 — — 48.551.252.954.154.955.556.056.456.8
400 — — 47.750.652.553.754.655.355.856.256.6
420 — — 46.950.152.053.354.355.055.656.056.4
440 — — 46.149.551.653.054.054.755.355.856.2
460 — — 45.348.951.152.653.654.455.155.656.0
480 — — — 48.350.652.253.354.254.855.455.8
500 — — — 47.750.251.853.053.954.655.155.6

Note: Minimum dew point selectable is 45°F.

10 15 20 25 30 35 40 45 50 55 60

cfm per person

Table 2. Supply air dew point temperature, 75°F at 55 percent RH space limit

Latent Load
Btu/h per Person

100 51.6 53.8 54.9 55.5 55.9 56.1 56.3 56.5 56.6 56.7 56.8
120 50.2 53.0 54.2 55.0 55.5 55.8 56.1 56.2 56.4 56.5 56.6
140 48.8 52.1 53.6 54.5 55.1 55.5 55.8 56.0 56.2 56.3 56.4
160 47.2 51.2 53.0 54.0 54.6 55.1 55.5 55.7 55.9 56.1 56.2
180 45.6 50.2 52.3 53.5 54.2 54.8 55.2 55.5 55.7 55.9 56.1
200 — 49.3 51.6 53.0 53.8 54.4 54.9 55.2 55.5 55.7 55.9
220 — 48.3 50.9 52.4 53.4 54.1 54.5 54.9 55.2 55.5 55.7
240 — 47.2 50.2 51.9 53.0 53.7 54.2 54.6 55.0 55.2 55.5
260 — 46.2 49.5 51.4 52.5 53.3 53.9 54.4 54.7 55.0 55.3
280 — 45.1 48.8 50.8 52.1 53.0 53.6 54.1 54.5 54.8 55.1
300 — — 48.0 50.2 51.6 52.6 53.3 53.8 54.2 54.6 54.9
320 — — 47.2 49.7 51.2 52.2 53.0 53.5 54.0 54.3 54.6
340 — — 46.4 49.1 50.7 51.8 52.6 53.3 53.7 54.1 54.4
360 — — 45.6 48.5 50.2 51.4 52.3 53.0 53.5 53.9 54.2
380 — — — 47.9 49.8 51.0 52.0 52.7 53.2 53.7 54.0
400 — — — 47.2 49.3 50.6 51.6 52.4 53.0 53.4 53.8
420 — — — 46.6 48.8 50.2 51.3 52.1 52.7 53.2 53.6
440 — — — 46.0 48.3 49.8 50.9 51.8 52.4 53.0 53.4
460 — — — 45.3 47.8 49.4 50.6 51.5 52.2 52.7 53.2
480 — — — — 47.2 49.0 50.2 51.2 51.9 52.5 53.0
500 — — — — 46.7 48.6 49.9 50.9 51.6 52.2 52.7

Note: Minimum dew point selectable is 45°F.

10 15 20 25 30 35 40 45 50 55 60

cfm per person

18 OAU-PRC003A-EN

Application Considerations

Table 3. Supply air dew point temperature, 75°F at 50 percent RH space limit

Latent Load
Btu/h per Person

100 48.4 50.8 51.9 52.6 53 53.3 53.6 53.8 53.9 54 54.1
120 46.8 49.8 51.3 52.1 52.6 53 53.3 53.5 53.6 53.8 53.9
140 45.2 48.9 50.6 51.5 52.2 52.6 52.9 53.2 53.4 53.5 53.7
160 — 47.9 49.8 51 51.7 52.2 52.6 52.9 53.1 53.3 53.5
180 — 46.8 49.1 50.4 51.3 51.8 52.3 52.6 52.9 53.1 53.3
200 — 45.7 48.4 49.8 50.8 51.5 51.9 52.3 52.6 52.8 53.0
220 — — 47.6 49.3 50.3 51.1 51.6 52 52.3 52.6 52.8
240 — — 46.8 48.7 49.8 50.7 51.3 51.7 52.1 52.4 52.6
260 — — 46 48.149.450.350.951.451.852.152.4
280 — — 45.2 47.4 48.9 49.8 50.6 51.1 51.5 51.9 52.2
300 — — — 46.848.449.450.250.851.351.651.9
320 — — — 46.2 47.9 49 49.8 50.5 51 51.4 51.7
340 — — — 45.547.348.649.550.250.751.151.5
360 — — — — 46.8 48.2 49.1 49.8 50.4 50.9 51.3
380 — — — — 46.3 47.7 48.7 49.5 50.1 50.6 51
400 — — — — 45.7 47.3 48.4 49.2 49.8 50.4 50.8
420 — — — — 45.2 46.8 48 48.9 49.6 50.1 50.6
440 — — — — — 46.3 47.6 48.5 49.3 49.8 50.3
460 — — — — — 45.9 47.2 48.2 49 49.6 50.1
480 — — — — — 45.4 46.8 47.9 48.7 49.3 49.8
500 — — — — — — 46.4 47.5 48.4 49.1 49.6

Note: Minimum dew point selectable is 45°F.

10 15 20 25 30 35 40 45 50 55 60

The Trane OAU utilizes recovered energy from the cooling process to reheat the air leaving the
evaporator coil as required to meet the discharge air setpoint. The reheat refrigeration circuit is
adequate to deliver enough reheat to supply neutral-temperature air (e.g., 75°F dry-bulb) under
most operating conditions. On very low load days, the reheat circuit may not contain enough
energy to meet the desired reheat setpoint.

cfm per person

Heating

The OA U has electric, heat pump, or g as heat option s. The elec tric he at option is available in 0°F–
80°F temperature rise offerings with SCR modulation. This means that the lowest temperature rise
provided depends only on heater size and unit airflow . Cal cul at e the tem perature rise to confirm
that it provides acceptable control. The electric heat will modulate to maintain heating setpoint.

When using hot water heat, the unit controller will modulate a field-provided coil control valve.
Provide an ethylene glycol and water mixture or other means of freeze protection for the hot water
coil if the OAU will be subject to sub-freezing temperatures.

Capacity Control

The capacity control system on the Horizon™ Outdoor Air Unit is flexible enough to accommodate
a variety of system applications. These applications include:

• treating outdoor air to supply a single space or multiple spaces or

• simultaneously meet building make-up air needs while controlling the temperature and relative
humidity of a single space.

Each of these applications requires careful consideration to achieve the desired results.

Discharge Air Control

For many multiple spac e, dedicated outdoor air systems, the O AU will continuously supply outdoor
air at a dry-bulb setpoint and a dew point that does not exceed its dew point setpoint. Th is control
approach is simple because it allows the OAU to function independent of local terminal unit
operation or actual space conditions. If the unit selection cri teria is determined using the method
suggested in“Establishing Capacity Requirements,” p. 17, the Outdoor Air Unit will limit the space
relative humidity to the target level.

OAU-PRC003A-EN 19

Application Considerations

Many dedicated outdoor air systems supply reheated air directly to terminal units or to spaces that
have terminal units performing local sens ible cooling. This results in the local terminal units re­cooling the previously re-heated outdoor air . Resetting the supply air dry-bulb temperature of the
Outdoor Air Unit offers the opportunity to minimize the amount of time re-cooling occurs. Refer to

“Cooling Setpoint,” p. 20 for more information.

Cooling Setpoint

Because the T rane O AU dehumidifies the outdoor air by cooling it, th is cool outdoor air can reduce
the sensible cooling load on the local terminal unit. At low space sensible loads, the cool outdoor
air may sub-cool the space, causing the local terminal unit to add heat (new energy heat).
Therefore, reset occupied Space Cooling Setpoint (SPCS—Space Control Sequ ence) or Evaporator
Cooling Setpoint (ECS—Outdoor Air Contro l Sequence) of the O A U to minimize space sensible re­cooling so the terminal unit with the lowest sensible load is almost at zero cooling capacity (within
the limit of the dew point setpoint). To take full advantage of space demand based dry-bulb reset,
you may need to size some of the local terminal units based on neutral outdoor air temperature.
This strategy will more effectively manage occupant comfort during seasonal changeover for two­pipe terminal unit systems. Because the OAU is not connected to the chiller or boiler plant,
accomplish this by resetting the Outdoor Air Unit SPCS or ECS to keep the critical zone at zero
heating capacity when the boiler is off and zero cooling capacity when the chiller is off. A Trane
Integrated Comfort™ system can provide this control capability.

Unoccupied Space Humidity Control

The Horizon™ O AU pro vides conditioned outdoor air for the ventilation and/or make-up air needs
of a building during occupied hours. It can also limit building relative humidity during unoccup ied
hours. To do this, provide a return air path to the OAU and place a relative humidity sensor in the
space served by the OAU or in a common relief air path (like a return corridor) if the OAU serves
multiple spaces. The unit will cycle as required to limit the space humidity to the unoccupied
Dewpoint Setpoint (NSDS) setpoint. Reheat and return air damper options are required for this
operation. For dedicated outdoor air systems ducted to terminal units, these units must cycle with
the operation of the Horizon OA U. A Trane Integrated Comfort™ system can provide this control
capability.

Space Control

For single space applications, the Horizon OAU can control space temperature and limit space
relative humidity. To do this, size the airflow to meet whichever is the highest: the space loads and
ventilation and/or make-up air needs of the application. Install a temperature sensor in the space
to provide temperature control and reset the supply air temperature. If reset of the supply air dew
point is desired, install a space relative humidity sensor in the space to provide relative humidity
limit control.

Outdoor Airflow Balancing

Establish final unit airflow through a field air balancing procedure. Change the fan speed through
replacement or fan sheave adjustment (belt drive indoor fan motor) or VFD Setpoint via the UC600
controller (direct drive fan motor).

Air to Air Energy Recovery

Energy recovery can significantly reduce HVAC system first-cost and operating energy costs.
You can use recovered energy for two purposes:

1. to temper or reheat supply air for independent control of sensible and latent capacity, or

2. to precondition outdoor air as it enters the building for ventilation.

The Horizon™ OAU offers refrigerant heat recovery for reheating the supply air. To precondition

20 OAU-PRC003A-EN

the outdoor air, use the optional total-energy wheel to recover energy from building exhaust.

Controlling the Total-Energy Wheel

One way to control an energy recovery device is to turn it on and off with the OAU system
exhaust fan. In this case, the total energy wheel enables when the unit is in occupied mode and
the exhaust fan is running. While this control method is certainly simple and effective in some
applications, it may not provide the expected energy saving benefit, particularly when cold air
(vs. neutral air) is supplied to the building.

Another more effective approach is to use the outdoor air dry-bulb to determine when to ener­gize or de-energize the energy recovery device. See Figure 11, p. 21 for an example of this simpli-
fied control. In addition to being more effective from a control standpoint, it’s also a very simple
control method because the wheel is enabled when all of the following are true:

• unit is in occupied mode,

• exhaust fan is enabled,

• Unit Main Control Module (MCM) calls for unit to operate in dehumidification, cooling, or
heating modes, and

• outside air temperature is above the frost protection setpoint (default setpoint 12°F).

If using the O AU to deliver cold, dry conditioned air to th e building (ou tdoor air is cooled to a low
dew point but not reheated), use the cooling setpoint control strategy (see “Cooling Setpoint,”

p. 20).

Application Considerations

Figure 10. Dry-bulb control in a cold DB/dry DP application

Figure 11. Dry-bulb control in a neutral DB/dry DP application

OAU-PRC003A-EN 21