york vrf system design and layout guide

YORK® VRF system design and layout guide

VA R I A B L E R E F R I G E RA N T F LOW SYS T E M S


JOHNSON CONTROLS | YORK® VRF GEN || SYSTEMS | DESIGN AND LAYOUT GUIDE

VRF technology gives building owners, architects, consulting engineers and mechanical contractors an innovative solution to address the common

challenge of reducing operating costs in buildings with varied heat loads and occupancy rates while delivering comfort to all areas.

Why variable refrigerant flow?

This guide will help you understand the important considerations when designing a VRF system for a given application: system selection, loads, and connection ratios.

In addition, system efficiencies and how they are measured, control options, wiring limitations, refrigerant piping, and the required outdoor installation space are addressed.

Guidance is also provided for complying with the relevant ASHRAE Standards (15 and 34).

This easy-to-understand guide will enable you to lay out a VRF system for multiple applications.

What you will learn in this guide

1JOHNSON CONTROLS | YORK® VRF SYSTEMS | DESIGN AND LAYOUT GUIDE


VRF EFFICIENCY

How Does a VRF System Work? .............................................................2

Why Choose a YORK® VRF System? .......................................................3

How is Efficiency Measured? .................................................................. 4

PRODUCT OVERVIEW

Outdoor Unit Capacities and Configurations ...........................................6

Outdoor Unit Operating Range ................................................................7

Indoor Unit Capacity Range .....................................................................8

VRF System Accessories ........................................................................9

Controller Options .................................................................................10

SYSTEM SELECTION, PIPING, WIRING, AND INSTALLATION

System Selection ................................................................................... 11

YORK VRF Selection Tool ......................................................................16

System Block Load and Peak Load ........................................................18

System Connection Ratio ......................................................................19

System Diversity ....................................................................................20

Refrigerant Piping ..................................................................................21

VRF Control Wiring ................................................................................22

Outdoor Unit Installation Space ............................................................23

ANSI / ASHRAE STANDARDS

VRF Systems and Outside Air Requirements in ANSI/ASHRAE Standard 62.1 .............................................................26

ASHRAE Standards 15 and 34 ..............................................................27

Summary ..............................................................................................32

Table of Contents

2 JOHNSON CONTROLS | YORK® VRF SYSTEMS | DESIGN AND LAYOUT GUIDE


A VRF system typically consists of one or more outdoor condensing units from which refrigerant is piped to a series of indoor fan coil units serving individual zones within building spaces. The system conditions the spaces by delivering to the indoor fan

coil units only the volume of refrigerant required to meet the heating or cooling needs of each zone. There are two basic types of YORK® VRF systems:

• Heat pump VRF systems

• Heat recovery VRF systems

How Does a VRF System Work?

VRF

Effic

ienc

y

Heat pump VRF systems are two-pipe systems that can be designed for ductless or

ducted applications. Precise heating or cooling can be delivered to multiple zones.

Heat recovery VRF systems are three-pipe systems that can also be designed for ductless or ducted applications. Precise heating and cooling is delivered with an extra measure of efficiency because the system can provide simultaneous heating and cooling while transferring any excess heat or cooling from one zone to another.



Why Choose a YORK® VRF System?

YORK® VRF systems offer:

Exceptional efficiency - Simultaneous Cooling and Heating Efficiency (SCHE) – the truest measure of VRF system efficiency – is up to 32.2, among the highest in the industry. In addition:

• Integrated Energy Efficiency Ratio (IEER) is up to 26.5

• Coefficient of Performance (COP) is up to 4.25.

• For YORK Mini VRF, the COP is up to 5.12 and the Seasonal Energy Efficiency Ratio (SEER) is up to 23.1.

Extreme flexibility – Owners can specify a complete and customized modular system built out of four basic building blocks:

outdoor unit, indoor unit, piping and controls.

Zoning – The zoning capability of a VRF system enables excellent energy efficiency while providing a comfortable environment for people in each zone. A zone can be part of a room, a whole room, or several rooms in a building.

Quiet comfort - A wide variety of indoor units are available in styles and capacities to fit multiple applications. Units operate quietly with sound ratings as low as 24.5 dB(A). Outdoor units have low sound ratings down to 51 dB(A).

VRF Efficiency

The YORK VRF Systems boast efficiencies up to:

• 32.2 SCHE• 26.5 IEER• 4.25 COP at 47° F• 2.60 COP at 17° F

Outdoor Unit Indoor Unit Piping Controls

YORK VRF System Building Blocks

Efficiency values are certified according to AHRI Standard 1230.



How is efficiency measured?

IEER is calculated as follows:

IEER = (0.02 x A) + (0.617 x B) + (0.238 x C) + (0.125 x D) where A, B, C and D are as follows:

Based on the weightings used in the IEER calculation, full load operation occurs only during times of extreme ambient temperatures. Full-load operation is only possible when ambient temperatures are at or above 95 degrees.

A = EER at 100% net capacity at AHRI standard

rating conditions

B = EER at 75% net capacity and reduced

ambient air temperature (81.5° F)

C = EER at 50% net capacity and reduced

ambient air temperature (68° F)

D = EER at 25% net capacity and reduced

ambient air temperature (65° F)

The higher the IEER, EER, SCHE, SEER and the COP, the greater the energy efficiency.

IEER

Integrated energy efficiency ratio (IEER) is an expression of a system’s cooling part-load efficiency. It is based on a weighted combination of a system’s EER at four capacity

points. The system is measured at different capacities and outdoor conditions according to AHRI Standard 1230.

EER

Energy efficiency ratio (EER) measures the capacity for a system divided by the power it uses, at a specific rating condition. The higher the EER,

the more efficient the system. This metric is typically used to measure the full-load efficiency of a system.

A VRF system is designed to be most efficient at part load. Therefore, a VRF system operating at 50% part load could be more than 50% more efficient than the rated full load EER value.

The actual energy efficiency for a VRF system could exceed the IEER rating depending upon equipment sizing, environment, load and use of the system.

VRF

Effic

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The IEER values for YORK® VRF and the minimum requirement specified in ASHRAE 90.1 2010 are shown in the figure above.

How is efficiency measured? (cont’d)

28

26

24

22

20

18

16

14

12

10

4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

IEER

Nominal Capacity (Ton)

YORK® VRF

ASHRAE 90.1

SCHE

The simultaneous cooling and heating efficiency (SCHE) value is the total system capacity (cooling and heating) ratio for a system when operating in heat recovery mode. SCHE ratings are tested with 50% of the indoor units in cooling and 50% of the indoor units in heating mode at an outdoor temperature of 47°F.

SEER

The SEER is defined as the total output provided by a unit/system during its normal annual usage period divided by its total energy input during the same period. A higher SEER rating means greater energy efficiency.

COP

Coefficient of performance (COP) is the ratio of output energy divided by the input energy. COP ratings are typically used to measure efficiency in heating mode for heat pump systems.

Which Efficiency Metric to Use

Numerous variables affect the efficiencies of HVAC systems. EER and COP only look at a system at a single point under a fixed condition. IEER is a better measure because it blends and weighs four different operating points in a season. It does not, however, take into account simultaneous cooling and heating, which is the true advantage of a VRF heat recovery system. SCHE, on the other hand, is the total system efficiency ratio when operating in heat recovery (both cooling and heating) mode.

Measuring HVAC system efficiency enables you to compare the effectiveness of different units and select the system that provides maximum comfort at optimum total cost.

VRF Efficiency



Outdoor Unit Capacities and Configurations

YORK® VRF Outdoor Units, in capacities from 3.0 to 36 tons with modular system

combinations, include heat pump and heat recovery units (see table below).

The capacity ratings are based on the AHRI 1230 Standard.

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Nominal Capacity Power

Supply(V/Ph/Hz)

System Type

# of Outdoor

Unit Modules

Outdoor Unit - Module Configurations# of

Compr.# of Fans

Connection Ratio (%)

Max # of Indoor Units Standard/Extended

Connection Ratio

Ton MBH 3Ton

4Ton

5Ton

6Ton

8Ton

10Ton

12Ton

14Ton

16Ton Min

Max Stand./

Ext.

3* 36208-

230/1/60—

Heat Pump

1

1

1

1

60130

6

4* 48 1

2

85* 60 1 105

6 72

208-230/3/60

460/3/60

Heat Recovery

1 70

130/150

15/8

8 96 1 65 20/8

10 120 1

2

60 26/8

12 144 1

55

26/10

14 168 1 36/12

16 192 1 40/14

18 216

2

1 1 3 360

46/18

20 240 2

4

4

52/18

22 264 1 1

55

56/20

24 288 2 59/20

26 312 1 1 64/22

28 336 1 1 64/24

30 360 1 1 64/28

32 384

3

2 1 6

6 64/3034 408 1 2

36 432 3

*Mini VRF

YORK VRF Outdoor Unit Capacities and Configurations



VRF heat pump and heat recovery units offer extended operating temperature ranges: cooling between -10°F and 122°F outdoor ambient temperatures (-10°F – 75°F in simultaneous heating and cooling mode) and heating between -13°F and 59°F (-11°F - 59°F in simultaneous heating and cooling mode).

The Mini VRF heat pump system can provide cooling down to 23°F.

In order to extend the low temperature ranges for cooling operation, additional accessories are used (see the VRF Engineering Manual).

Outdoor Unit Operating Ranges and Configurations (continued)

Product Overview

Extended outdoor ambient temperature operating ranges make YORK VRF systems an excellent choice even in extreme climates.

Extended operating

rangesVRF HEAT PUMP

*With low-ambient kit installed, the cooling operating range extends as low as -10°F.

-20°F 0°F 20°F 40°F 60°F 80°F 100°F 120°F

COOLING MODE

HEATING MODE

VRF HEAT RECOVERY

-20°F 0°F 20°F 40°F 60°F 80°F 100°F 120°F

COOLING ONLY MODE

HEATING ONLY MODE

-20°F 0°F 20°F 40°F 60°F 80°F 100°F 120°F

*

*

* SIMULTANEOUS COOLING

AND HEATING



Tonnage 0.5 0.7 1.0 1.3 1.5 2.0 2.3 2.5 3.0 4.0 4.5 5.0 6.0 8.0

1-Way Cassette Indoor Unit


4-Way Mini Cassette Indoor Unit


Ceiling Suspended Indoor Unit

Wall Mount Indoor Unit

Floor Exposed Indoor Unit

Floor Concealed Indoor Unit

Ducted High Static Indoor Unit

Ducted Medium Static Indoor Unit

Ducted Slim Indoor Unit

DedicatedOutside Air System (DOAS)

EconoFresh Economizer Indoor Unit

Multi-Position Air Handler Unit

Indoor Unit Capacity Range

The indoor units, in capacities from 0.5 to 8 ton are available in a variety of ducted and

non-ducted units and different styles and configurations to fit a wide selection of applications

(see table below). The capacity ratings are based on the AHRI 1230 Standard.

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The available options for the IU units are as follows:

VRF System Accessories

Unit Type Accessory Description

Outdoor Units

Drain adapter For connection of field-supplied drain pipe to drain pan

Low Ambient Kit For cooling operation at extended low ambient air temperature

Protection Net (Rear) For protection of outdoor unit heat exchanger

Snow Protection Hood (Upper) Hood for protecting the OU air inlet/outlet from snow/hail

Air Filter Washable air filter with mounting flange

Wind Guard Protects air inlet/outlet from strong winds

Wind Prevention Tool Prevents the OU from tipping over

Toppling Prevention Tool Prevents OU from tipping over when Snow Protection Hood is in use

Ducted Indoor Units

3-Pin Connector Cable Kit that provides remote start/stop capability for IU and operating status of IU functions

Relay and 3-Pin Connector Kit Relay and 3-Pin Connector Kit used for input/output signals between central controller and IU

Remote Sensor Remote air temperature sensor

Air Outlet Shutter Plate Plate for blocking of air outlet

Fresh Air Intake Kit Kit to enable connection of outside air to the IU

Panel with Motion and Radiant Heat Sensors Panel with motion and radiant heat sensor

Motion Sensor Kit Kit for detection of motion

Duct Adapter Kit for connection of outside air duct to the IU

Grille for Front Discharge Grille used for front air outlet from IU

Non-Ducted Indoor Units

Air Outlet Shutter Plate Plate for blocking of air outlet

IR Receiver Kit Kit for use with Wireless Zone Controller CIR01

Filter Box Mounting box for Air Filter

Drain Pump Kit Drain pump kit

Rectorseal drain pump Drain pump kit

3-Pin Connector Cable Kit that enables remote start/stop capability IU and operating status

Relay and 3-Pin Connector Kit Relay and 3 Pin Connector Kit used for input/output signals between central controller and IU

Remote Sensor Remote air temperature sensor

Product Overview



Building Automation System Integration

YORK® VRF Controllers Capability

Wired Zone Controller

Up to 16 Indoor Units

Simplified Wired Zone Controller


Wireless Zone Controller


Mini Central Station

Up to 32 groups of Indoor Units

(max 160 Indoor Units)

Large Central Station

Up to 64 groups of Indoor Units (max 160

Indoor Units)

Computerized Central

Controller

Up to 2,048 BMS groups of Indoor Units

(max 2,560 Indoor Units)

Web-Enabled Central

Controller

Up to 128 groups of Indoor Units

(max 160 Indoor Units)

Controller Options

VRF Systems offer a wide range of control systems to suit multiple applications:

Wireless Zone ControllerMODEL CIR01

Simplified Wired Zone ControllerMODEL CIS01

Wired Zone ControllerMODEL CIW01

Centralized Controllers

Mini Central StationMODEL CCM01

Computerized Central ControllerComputerized Central Controller Software: MODEL CCCS01

Computerized Central Computer Adapter: MODEL CCCA01

Zone Controllers

Large Central Station MODEL CCL01

LonWorks® Adapter MODEL CLW01

Web-Enabled Central ControllerMODEL CCWEB01

Johnson Controls VRF Smart Gateway MODEL CBN02

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Heat Recovery or Heat Pump

System Selection

Heat Recovery

The main benefit of a heat recovery VRF system compared to a heat pump system is that it gives occupants the ability to control both the mode and the temperature in their individual zones. Heat recovery VRF systems also have the potential for

additional energy savings when some zones are in cooling mode while other zones are in heating mode. The additional energy savings with a heat recovery VRF system varies generally based on geographic location, building layout, and usage.

For a VRF system to provide simultaneous heating and cooling (heat recovery), additional units (called change-over boxes) are needed to alternate the flow of refrigerant.

SYSTEM ADVANTAGES BENEFITS

Heat pump VRF system • Precisely heats or cools multiple zones • Provides extreme system design flexibility

Heat recovery VRF system• Allows simultaneous heating/cooling• Allows transfer of excess heat/cooling from one

zone to another

• Maximizes comfort and efficiency• Maximizes design flexibility• Increases occupant comfort to specified zones

System Selection

COB COB COB COB

Outdoor Unit(s)

Change-Over Boxes

Indoor Units



System Selection (cont’d)

Heat Pump

A heat pump system uses only two pipes for circulating the refrigerant. It provides extreme system design flexibility and

allows heating or cooling in all of the indoor units but not simultaneous heating and cooling.

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Outdoor Unit(s)

Indoor Units




Zoning

A VRF system should always be designed based on a sound understanding of how the space is laid out and used. By dividing a building into zones based on heat load, usage or usage schedule, or a combination thereof, the zoning can be optimized. A more economical design can in some cases be achieved by combining zones with similar heating/cooling requirements.

Layout Optimization

The diagrams on the right show two potential layouts for an office building VRF heat recovery system. The top diagram shows an initial layout treating each area as a separate zone, each with its own change-over box to deliver heating or cooling at individual set points.

The bottom diagram shows an optimized layout where similar cooling and heating needs are consolidated into single zones. In this case, grouping is more cost-effective since fewer change-over boxes are needed.

System Selection

Outdoor Unit

Indoor Unit

Change-Over Box

Piping

Initial layout with multiple separate zones.

Optimized layout - grouping zones with similar usage reduces the number of change-over boxes.




Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Lobby

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

HP2

HP1OfficeConference

RoomConference

Room

Office

Office

N

S

W E

HR2

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Lobby

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office HR1OfficeConference

RoomConference

Room

Office

Office

N

S

W E

Two Heat Recovery (HR) Systems

For heat pump system layouts, it is recommended that indoor units be grouped with outdoor units across common load profiles.

For heat recovery system layouts, it is recommended that indoor units be grouped with outdoor units across opposite load profiles.

If more than one system is required, and the zones have similar load profiles, orientation can be used for zoning.

The diagrams on the right are examples of an office building with perimeter offices and conference rooms where zoning can be based on orientation/location of zones. The top diagram shows two heat pump systems. The bottom diagram shows two heat recovery systems.

Two Heat Pump (HP) Systems

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Mixed Heat Recovery (HR) and Heat Pump (HP) Systems

Combining heat pump and heat recovery systems can increase cost-effectiveness. In the diagram on the right, heat recovery systems are used for office spaces around the building’s perimeter to offer optimal heating and cooling - including the ability to address the influence of strong sunlight. A heat pump system is used for interior conference rooms since the load is not influenced by strong morning or afternoon sunlight.

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

Lobby

Office

Office

Office

Office

Office

Office

Office

Office

Office

Office

OfficeConferenceRoom

ConferenceRoom

Office

Office

N

S

W E

HR1

HP

HR2

System layout showing a mix of heat pump and heat recovery systems for increased cost-effectiveness.

System Selection



YORK® VRF Selection Tool

Web-Based Program

The YORK VRF Selection Tool (available online for registered users at VRFPro.com and UPGnet.com/HVACnavigator.com)

intuitively guides users step-by-step through VRF equipment selection, pipe sizing, wiring, etc., to quickly and accurately

choose an appropriate and cost-effective equipment package for each project.

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The YORK VRF Selection Tool software program automatically:

n Designs accurate final system drawings including piping and wiring diagrams.

n Accurately selects systems using a system sizing analysis. The process starts with the indoor fan coil units so that outdoor units are optimally sized.

n Uses proprietary algorithms to figure the system size using data input on the indoor units, load, and measurements so a system does not include capacity that will go unutilized.

The tool will generate a report based upon user input.

YORK® VRF Selection Tool (cont’d)

Selection Software ReportVA R I A B L E R E F R I G E RA N T F LOW SYS T E M S

System Selection



System Block Load and Peak Load

The System Block Load value is used to select the appropriate outdoor unit for the VRF system. It is determined by the building load calculations and defined as the maximum total peak load (cooling/heating) for all served zones at any given time of the day.

The Zone Peak Load value is used to select the appropriate indoor unit(s) for the served zone. It is specified as the maximum load at the design conditions for the zone.

The table below shows an example for determination of System Block Load and Zone Peak Load based on building load calculations.

Zone Load (Btu/h) at

10:00 AM 1:00 PM 4:00 PM Daily High

Zone A 5,000 12,000 13,000 13,000

Zone B 3,600 6,000 3,000 6,000

Zone C 900 12,000 15,000 15,000

Zone D 13,500 21,000 9,000 21,000

Total 23,000 51,000 40,000 55,000

Zone Peak Load(for indoor unit

sizing)

Maximum System Block Load

(for outdoor unit sizing)

In this example, the outdoor unit capacity needs to be at least 51,000 Btu/h and the capacity for indoor units in Zone A, B, C, and D needs to be at least 13,000, 6,000, 15,000, and 21,000 Btu/h, respectively.

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System Connection Ratio

The System Connection Ratio for a VRF system is used to define certain technical limits for a VRF system. It does not define diversity.

The System Connection Ratio is the total sum of indoor unit capacity index numbers divided by the total outdoor unit capacity index number for the system.

A VRF system with a combined indoor unit capacity index larger

than the combined outdoor unit capacity index, has a ratio that is greater than 100%. Consequently, if the outdoor unit combined capacity index is higher than the index for indoor units, the ratio is less than 100%.

Connection ratio ranges, maximum number of indoor units, etc. for different outdoor unit capacities are listed in the table on page 6.

Most VRF systems allow the ratio to be between 50% and 130% (or 150%). The generous range enables flexibility in the system design. However, if a system is designed with a connection ratio outside the allowed range, it might lead to malfunction and/or reduced comfort levels for the occupants, or both.

System Selection



System Diversity

System diversity is the ratio of the maximum system load demand at any given time to the maximum capacity of the outdoor unit at design conditions.

For example, if the maximum load at any given time is higher than the maximum capacity of the outdoor unit at design conditions,

the system diversity is negative. This means that the outdoor unit is undersized and capacity will fall short of the demand. Choosing a negative system diversity can reduce the system size and the number of required outdoor units, and consequently yield a lower total system price. However, it

must be noted that a system capacity short of the demand can at times result in less than optimally comfortable zones.

A positive system diversity means that the outdoor units are oversized and have enough capacity to always produce comfortable zones.

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A VRF system allows generous piping distances. However, there are maximum lengths that refrigerant piping must stay within to ensure proper pressure and enable proper oil return.

The general refrigerant piping limitations for YORK® VRF systems are as follows:

Refrigerant Piping

Maximum Distances HP HR

Total piping, one-way 3,281 ft.

Vertically between OU and IU OU above IU (OU below IU)

360 ft. (131 ft.)

Vertically between IUs 98 ft. 49 ft.

1st branch and IU 295 ft.

Linear Length, OU and IU 541 ft.

Branch and IU 131 ft.

98(HP)

49(HR) 295

541

360

131

(131)

OU above IU

OU below IU

Longer piping lengths

System Selection



VRF Control Wiring

The general control wiring limitations are as follows:

The H-LINK II transmission system is used for communication between the units in the VRF system.

A maximum of 64 refrigerant groups and 160 indoor units can be controlled by one single central control device. Note the example at right.

A two-conductor, non-polar, shielded cable over AWG18 is used for the communication connections.

Max Wiring

Distance (ft)

A Point to Point 3,280

B Indoor Unit to Controller 1,640

B

A

Outdoor Unit

Indoor Unit

Central Controllers

Building Automation System Integration

Johnson Controls VRF Smart Gateway

LonWorks®

refrigerant piping H-Link wiring

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The location of the outdoor unit(s)

is an important consideration,

especially in cases where the

unit(s) may be confined or

restricted with one or more walls

in close proximity. Adhering to the

minimum distance requirements

will help ensure exhaust and supply air can perform as designed, and overall outdoor unit function is not impacted.

The diagrams on this and the following page show the minimum distances that must be kept to

ensure correct function of the VRF

and Mini VRF systems. For other

layouts of the outdoor units, please

see the VRF Engineering Manual

and the Service Manual or contact

your manufacturer’s representative

or distributor.

YORK® Heat Pump and Heat Recovery Outdoor Unit Installation Space

A

F R

Front Front

R

D B

Front

R

D

F

Front

R

D

O

D

F

One Wall - Front Min. Distance (“)

One Wall - Rear Min. Distance (“)

A 60 60

F 20+Wall Height/2 20

R 12 12+Wall Height/2

Two Walls - Single Unit, Min. Distance (“)

Two Walls - Multiple Units, Min. Distance (“)

B — 16

D 0.5 8

R 12 12

Three Walls - Multiple Units - Front to Rear Min. Distance (“)

D 0.5

F 20+Wall Height/2

R 12+Wall Height/2

Four Walls - Multiple Units - Front to Rear Min. Distance (“)

D 8

F 20+Wall Height/2

R 12+Wall Height/2

O 32

For additional (more detailed) piping limitations, see the VRF Engineering Manual and the Service Manual.

System Selection



YORK® Heat Pump and Heat RecoveryOutdoor Unit Installation Space (cont’d)

Front Front Front

R

D B B

Front Front Front

B B

F

Front Front Front

R

D B

Front Front Front

F

F

Three Walls - Multiple Units - Front to Rear Min. Distance (“)

B 0.75

D 0.5

F 20+Wall Height/2

R 12+Wall Height/2

Three Walls - Multiple Units - Rear to Rear Min. Distance (“)

B 0.75

D 0.5

F 20+Wall Height/2

R 36

For additional (more detailed) information, see the VRF Engineering Manual and the Service Manual.

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Installation Options

Multiple UnitsOpen Sides

Distances in Inches

Min

. 40

Min. 4Max. 12

Min. 14

Max. 12

Min

. 40

Min. 14

Single UnitOpen Sides

Side View Distances in Inches

Single Unit

and AboveOpen Sides Single Unit

Open Above

Front

Min. 8

Front

Min. 12

Min. 2 Min. 4

Top View Distances in Inches

Min. 4

Min. 12


Multiple UnitsOpen Sides and Above

Front Front


Distances in Inches

Min

. 40

Min. 4Max. 12

Min. 14

Max. 12

Min

. 40

Min. 14



Single Unit


Open Above

Front

Min. 8

Front

Min. 12

Min. 2 Min. 4


Min. 4

Min. 12



Front Front


Distances in Inches

Min

. 40

Min. 4Max. 12

Min. 14

Max. 12

Min

. 40

Min. 14



Single Unit


Open Above

Front

Min. 8

Front

Min. 12

Min. 2 Min. 4


Min. 4

Min. 12



Front Front


Distances in Inches

Min

. 40

Min. 4Max. 12

Min. 14

Max. 12

Min

. 40

Min. 14



Single Unit


Open Above

Front

Min. 8

Front

Min. 12

Min. 2 Min. 4


Min. 4

Min. 12



Front Front

YORK® Mini VRF Heat Pump Outdoor Unit Installation Space

System Selection

For additional (more detailed) information see the Mini VRF Engineering Manual.



VRF Systems and Outside Air Requirements in ANSI/ASHRAE Standard 62.1

For VRF systems, outside air can be introduced in several different ways to comply with ANSI/ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality.

Generally, conditioned or non-conditioned outside air can be introduced directly to the air intake of a VRF indoor unit or to each zone.

Each method has advantages and disadvantages.

Method Advantage Disadvantage

Unconditioned Air to the Room• Works with any type of VRF indoor unit

• Typically requires upsized VRF

• Fan, filter, ducts needed

Unconditioned Air to the VRF Indoor Unit

• Interlocked controls

• No separate air supply grilles

• Fan, filter, ducts needed

• Typically requires upsized VRF

Conditioned Air to the Room

• The DOAS and EconoFresh indoor units provide conditioned outside air and are seamlessly integrated into the YORK VRF system (see also below).

• Requires separate unit

Conditioned Air to the VRF Indoor Unit

• No separate air supply grilles

• Does not add load to the VRF

• Requires separate unit for conditioning supplied air

• Not all indoor units can be used

EconoFresh

The unique YORK VRF EconoFresh/Indoor Unit combination provides energy-saving free cooling when the outdoor air temperature is lower than the indoor

temperature. In addition, it can maintain good indoor air quality by automatically providing sufficient levels of conditioned outside air.

DOAS

The YORK® VRF Dedicated Outside Air System (DOAS) provides a decentralized and zoned approach to conditioning and supplying outside air.

ANSI

/ASH

RAE

Stan

dard

s



ASHRAE Standards 15 and 34

Not intended as a substitute for the national, state and local codes.The contents herein are NOT approved by ASHRAE, CSA and do not imply an ASHRAE or CSA endorsement.

Apply ASHRAE Standard 15 requirements on the system design in four basic steps:

STEP 1. Develop a preliminary system layout

STEP 2. Determine the amount of refrigerant in the system(s)

STEP 3. Verify that the design complies with Standard 15 requirements

STEP 4. Remedy the situation if a room is too small

These standards are recognized as the main guide for personal safety involving refrigeration systems. The standards strive to ensure a safe application of refrigerant systems by limiting the maximum charge so that a complete discharge due to a leak into a small, occupied, and enclosed room can never exceed the allowable limit. As with most standards, ASHRAE Standard 15 is an application-based standard, not an equipment design guide, so substantial engineering judgment can be required when designing a system. It is recommended to review any local code as well when designing a system.

The safety classification of R410A in ASHRAE Standard 34 is group 1 (meaning non-toxic and non-flammable), it has no ozone-depletion potential and it meets the stringent mandates of both

the Montreal Protocol and the U.S. Environmental Protection Agency. However, due to the ability to displace oxygen, Addendum L to ASHRAE Standard 34-2010 has established that the maximum value for R410A is 26 lbs/1000 ft3 of room volume for occupied spaces.

For Institutional Occupancies (a premise where the occupants cannot readily leave without assistance of others), the maximum is reduced to 50% (13 lbs/1000 ft3).

Since the indoor unit fan coils are in direct contact with the air being distributed, a VRF system

is classified as a Direct System according to Standard 15. A Direct System is also by definition classified as a High Probability system, meaning that a leak of refrigerant can potentially enter into occupied space.

It is recommended to apply the Standard 15 requirements on the system design in four basic steps as follows:

ANSI/ASHRAE Standards



ASHRAE Standards 15 and 34 (cont’d)

STEP 1Develop a preliminary layout of the complete system to meet the heating/cooling requirements of the project.

STEP 2Determine the total amount of refrigerant.

This calculation can either be done manually according to guidelines in product documentation or by using the VRF Selection Tool software. If layout has to be revised, the software will recalculate the pipe sizes and refrigerant charge automatically.

STEP 3Verify that the initial layout of the VRF system complies with the Standard 15 requirements by checking refrigerant piping locations and also determining the occupancy classification for the room(s) and the room volume(s) for the smallest occupied room(s).

According to ASHRAE Standard 15, volume calculation shall be based on the volume of space to which the refrigerant disperses in case of a leak. This is an important section in Standard 15 and it should be considered if other parts of the Standard do not give clear enough directions.

The plenum space above a suspended ceiling can be considered a part of the room if it is a part of the air supply or return system.

Refrigerant piping location

According to Standard 15, refrigerant piping must not be less than 7.25 ft (2.2 m) above the floor unless the piping is located against the ceiling and is permitted by the authority having jurisdiction (AHJ). Also, refrigerant piping cannot be placed in a shaft containing a moving object and must not be installed in an enclosed public means of egress. Refrigerant piping also must be properly supported and, if it is installed in concrete floors, the piping must be encased in pipe duct.

STEP 4Remedy the situation if the calculated room volume is too small in relation to the actual refrigerant charge in the system. Generally, there are three ways to remedy this:

1. “Increase” the room volume used in calculations

2. Relocate/remove piping or indoor unit fan coil

3. Reduce the refrigerant charge by dividing the refrigerant circuit into multiple smaller systems

See detailed explanations on the following pages.

ANSI

/ASH

RAE

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Permanent openings

If a room is too small for the amount of refrigerant, it might be possible to increase the room volume used in the calculations by “connecting” it to other rooms by using louvers, transfer grilles, door undercuts, or similar equipment. However, since ASHRAE Standard 15 does not address how to calculate a permanent opening, this should be determined by the Engineer of record and/ or the AHJ.

Ventilation

When occupied space is served by a mechanical ventilation system, the entire air distribution system must be analyzed to determine the worst-case distribution of leaked refrigerant. According to the formal interpretation IC 15-2007, it is never permissible to increase the allowable refrigerant limits due to dilution by supply and/or exhaust air ventilation.

Doors

A regular door that cannot be closed between two rooms should satisfy the requirement of enabling connected spaces. Removing the door completely is the safest way to make sure that the rooms are always connected.

Suspended ceiling

Since ASHRAE Standard 15 does allow the space above a suspended ceiling to be used in calculating the room volume if it is a part of the air supply or return system, an option to consider is removing the ceiling completely. Alternatively, the air ducts can be reconfigured so the return air path is a part of the space above the suspended ceiling (see diagram below).

Step 4, Remedy 1 - Increase the room volume used in calculations

Plenum

OutdoorUnit

Duct

Occupied space = Volume of Room and Plenum

Suspended Ceiling





Relocate the indoor unit fan coil and duct it to several rooms

If the alternatives for “increasing” room volume are not possible, an alternative is to install the indoor unit fan coil outside the room that

is too small. By ducting the supply air to several rooms, the rooms would be considered connected according to ASHRAE Standard

15. If a leak occurs in the indoor unit fan coil, the refrigerant would be dispersed to both rooms, as shown in the figure above.

Room A Room B

IndoorUnit

Air Duct

Occupied space = Volume of both rooms

OutdoorUnit

Step 4, Remedy 2 - Relocate/remove piping or indoor unit fan coil

Remove indoor unit fan coil from system

If previously described methods to “increase” the room volume are not possible, consider removing the indoor unit fan coil from the

system and install a separate split unit to handle the load in the room. Removing the indoor unit fan coil from the system also

lowers the total refrigerant charge in the system.

ANSI

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RAE

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35’

25’

10’

10’

30’ 15’ 15’

Initial Layout

15’ 15’ 15’

20’

15’

10’

10’

30’

15’ 15’ 15’

Revised Layout

Consider decreasing the refrigerant charge in a single circuit by dividing a system into multiple smaller and completely

separate circuits. This change dramatically reduces the refrigerant charge in a single circuit. Due to the modularity

of VRF technology, the cost per ton of cooling/heating is very similar for several smaller systems or one larger system.

Step 4, Remedy 3 - Reduce the refrigerant charge by dividing the refrigerant circuit into multiple smaller systems

Optimize the piping layout

An additional remedy is to review the piping layout to understand if it can be altered to reduce refrigerant and piping. Reduced lengths of the main distribution piping can decrease the refrigerant charge in the circuit considerably. The revised piping layout, as shown in the diagram on the right, has approximately 80% refrigerant charge compared to the initial layout.



VA R I A B L E R E F R I G E RA N T F LOW SYS T E M SSu

mm

ary

Summary

The YORK® VRF system is a modular, flexible solution with models that can heat and cool different zones. The system offers an array of advantages over conventional systems:

Energy efficiency – the system essentially eliminates air duct losses. Variable speed compressors with wide capacity and precise modulation help maintain each zone’s temperature within a narrow range while providing extremely high part-load efficiency.

Comfort - users can establish temperature set points for each room / zone for personalized comfort. Indoor units are extremely quiet.

Flexibility – a VRF system has four basic building blocks: outdoor unit, indoor unit, piping and controls. This modularity makes VRF technology an exceptionally flexible solution for almost any building.



Notes

Johnson Controls, the Johnson Controls, YORK® and Metasys® logos are registered trademarks of Johnson Controls, Inc., or its affiliates, in the United States of America and/or other countries. BACnet® is a registered trademark of ASHRAE.

© 2018 Johnson Controls, Inc. P.O. Box 423, Milwaukee, WI 53201 Printed in the USA PUBL-7672v3 March 2018 www.johnsoncontrols.com

www.york.com/vrf

Industry certifiedYORK VRF systems are Intertek ETL Listed (Canada & USA), signifying that they comply with the standard of Heating and Cooling Equipment (ANSI/UL 1995 and CAN/CSA C22.2 No. 236-11, 4th Edition, October 14, 2011). The systems are also certified by the Air Conditioning, Heating & Refrigeration Institute.

Variable Refrigerant Flow (VRF) Multi-Split AC and HPAHRI Standard 1230

For more details on terms, conditions, and limitations, please refer to the warranty certificate.

Contact your sales person or visit our warranty support center at [email protected] for specific eligibility requirements.

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