VRF Systems presentation

7/25/2019 VRF Systems presentation

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VRF Systems: The

Good, The Bad and TheUgly

Mark Hydeman, PE, Principal

Hwakong Cheng, SeniorMechanical Designer

Taylor Engineering, LLC

http://www.taylor-engineering.com

VRF SYSTEMS: THE GOOD, THE BAD AND THE UGLY SLIDE 1

VRF SYSTEMS: THE GOOD, THE BAD AND THE UGLY JUNE 2 2011


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Logistics

Safety

Restrooms

Recycling

Cell phone etiquette

Lunch


Review forms

Webinar etiquette

PG&E Resources

Rebates Tool Lending Library

Marlene Vogelsang ([email protected])


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Agenda

Topic Speaker(s)

Intro and Overview M Hydeman

BREAK

VRF Manufacturer Perspective R Wilmarth & S Khayatian

BREAK

VRF Design Perspective H Cheng & M Hydeman


LUNCH

VRF Owner's Perspective T Rabiah

BREAK

VRF Cx Perspective D Sellers

BREAK

Discussion and Wrapup All


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Handouts

You can get a copy of the handouts in PDF format asfollows:

Type the following link into your web browser:

http://www.taylor-engineering.com/ftp/PECClassHandouts.html

Click on the link for VRF Systems to download the


Acrobat file of the presentation.


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Speakers

Mark Hydeman, PE, Principal, Taylor Engineering, [email protected]

Ruben Willmarth, Mitsubishi Electric [email protected]

Sherwin Khayatian, Norman S. [email protected]


Hwakong Cheng, Senior Mechanical Designer, TaylorEngineering, [email protected]

Tal Rabiah, PE, Sr. Mechanical Engineer, UCSC

[email protected] David Sellers, PE, Facility Dynamics

[email protected]


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Introduction

Who are you?

Facility Operations or Engineering

Design Consultant

Contractor

Vendor


Other

What brings you here?


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VRF Systems: The


Ruben Willmarth, Regional Mgr.

Mitsubishi Electric, HVAChttp://www.mitsubishipro.com

VRF SYSTEMS: THE GOOD, THE BAD AND THE UGLY SLIDE 1VRF SYSTEMS: THE GOOD, THE BAD AND THE UGLY JUNE 2 2011


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VRF Systems- The Good, The Bad & The Ugly

Two kinds of VRF

The Value of Heat Recovery

Piping


Economizers & Ventilation


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Applications The Bad



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Applications The Ugly



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Two kinds of VRF

Heat Pump or Heat Recovery?

Who do you serve?

Would a 2-pipe Hydronic work here? Or not?

Is it a cooling only application?


Small zones?

Hotel or Assisted Living?


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VRF Heat Pump Technology



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VRF Heat Recovery Technology

Simultaneous cooling and heating



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Comfort = Productivity

The lesser of Heat or Cool is essentially free

Most often occurs between 35F-65F, or with special

applications

New o tions to recover heat for DHW or HHW


Must always remember it is an applied benefit


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VRF Systems Heat Recovery Operation




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What Makes Heat Recovery DifferentSample Building in Part Load: OA Temp 50oF

3000 BTU

3000 BTU

Elect

Janitor

Break RoomLobby/

Waiting Room

ConferenceRoom

Cubicle Area

Open WorkRoom

6000 BTU

12000 BTU

6000 BTU

3000 BTU


Simultaneous Load:

Cooling: 27000 BTU

Heating: 21000 BTU

3000 BTU

6000 BTU

3000 BTU

Office #1 Office #23000 BTU WomenMen

6 Ton Heat Recovery System


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What Makes Heat Recovery Different

Cooling Power Input PURY-P72

5.00

6.00

7.00 72,000

B

6.48


0.00

1.00

2.00

3.00

4.00

0 12000 24000 36000 48000 60000 72000 84000

System Load BTUH

PowerInputKW

27,000

B

2.38


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What Makes Heat Recovery Different

Outdoor Temperature Power Input Correction

(For a 68 Indoor WB Temperature)

2.1000

2.2000

2.3000

2.4000

2.38

95


1.5000

1.6000

1.7000

1.8000

1.9000

2.0000

0 10 20 30 40 50 60 70 80 90 100

OA Temperature FDB

PowerInputKW

1.87

50


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What does this mean

Getting 27,000 BTUH of cooling and 21,000 BTUH of

heating, while providing only 1.87 KW to the outdoor unit.

This savings cannot be realized without the ability to do

simultaneous heating and cooling.

VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

SLIDE

13

,C 25.7


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Value of Heat Recovery to Hot Water

72 . C $10,000

A:

C C, B A

72,000 B/=21.1 *8760=184,836 / 100%

VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

SLIDE

14

184,836 $0.10/ 1/1.00 = $18,484 /

.

72,000 B/ 8760/100000 /=6,307.2 /

80%

6,307.2 $1.25/ 1/0.80 = $9,855 /


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Piping with VRF Systems

1. Always use type ACR copper piping

2. Always specify brazing with dry Nitrogen

3. Always specify pressure test with dry Nitrogen(550psi)

4. Always specify triple evacuation to


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A Good installation

VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

SLIDE

16


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A Good installation

VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

SLIDE

17


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Piping The Bad



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Piping The Bad



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Piping The Ugly

No accommodation

for thermal expansion



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VRF Controls



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VRF Controls- Which to Use?

. &

.



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Central Controllers

2000 AC /



CB

Consider when 5-10 Zones or more for easier scheduling

Use for remote access, alerts, IPhone, etc.

40

C C


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1. B,

, C,

2. A C B,


. .

C


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Economizers with VRF

They are available, but are they a benefit?

Offsets Heat

Recovery energy


Can increase

fan energy

Can Model in

Energy Pro


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Economizers with VRF



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15% Distributed OSA

Pair of 12 Dia. Ducts

Ventilation with VRF Systems

1. C C/

2. C/ (DA)


Air

30 Diameter

Ductwork

15% Central OSA

Single 16Dia Duct

1200 CFM

Space required to deliver 20 tons of cooling


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.




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( !)




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Questions



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VRF Systems: The


Sherwin Khayatian, MBA

Norman S. Wright MEC

http://www.norman-wright.com



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VRF Design Pitfalls

1. Over Zoning the Floor Plan One Fan Coil, Separate Point of Changeover per Room

2. Heat Pump versus Heat Recovery Applications

Picking the Right # of Changeover Points

Grouping Fan Coils on a Common Point of Changeover3. Heat Recovery: Establishing Cooling Only Zones

Comfort Cooling and Process Cooling

4. Zone Controller Application and Misconceptions

5. Centralized Controller. The Best Money you ever spent. Is a Separate BAS even required?

If so, what functions should a 3rd party BAS provide?


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VRF Design Pitfalls - Over Zoning the Floor Plan

One Fan Coil, Separate Point of Changeover per Room This is the Most Expensive Configuration possible

o This is usually a requirement for Hotel Guest Rooms

Multiple Fan Coils on a Common Point of Changeover

This can shave some costs and in some cases is an appropriatesolution for Office Spaces .

o This can be done so long as the Capacity of the ChangeoverDevice is not exceeded (i.e. No more than 8 Tons of Fan Coils perPoint of Changeover; Heat Pumps Points can be even bigger)

o This is good design practice when you have multiple fan coils

serving a common zone (i.e. Fan Coils should change over fromHeat to Cool and vice versa together as a group)

o Can also be considered for fan coils serving partitioned spaces thatshare a common load profile (i.e. Individual offices on sameexposure). This will reduce equipment costs.


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Single Floor Office Example 10,000 ft office space

4 open plan office spaces, 8 single offices & a server room Office Space has a peak load of 26 tons & block load of 20 tons

Server room has a 2 ton load

Engineer assumes that customer needs individual temperature control in each room

*

.

.

.

.

.

.

.

.


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Typical Office Example

As the customer is looking for temperature control per zone this would mean

a fan coil & branch selector box per indoor unit

This is an effective, efficient solution but can increase first cost

Approximate VRV installed cost 110%

0

BSVQ36

BSVQ

36

BSVQBSVQBSVQBSVQ

60606060BSVQBSVQBSVQBSVQ

36363636

BSVQ

36

BSVQ

36

BSVQ

36

BSVQ

36


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Combining indoor units in the same heat/cool changeover zone onto a common branch selector box

provides the most cost effective solution and meet the customers needs This reduces overall equipment and installation costs

Approximate VRV installed cost 78%

0

BS

BSVQ

96


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The most cost effective solution for this would be to zone the system as you would a VAV system

This reduces overall equipment and installation costs Approximate Installed Cost 73%

This does not meet the customers requirements of temperature control per zone

BSVQ

36

BSVQ

60BSVQ

0


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VRF Design Pitfalls

Heat Pump versus Heat Recovery Applications Picking the Right # of Changeover Points Grouping Fan Coils on a Common Point of Changeover

For Grouping, similar concept as Fan Coils on a CommonBSVQ for a Heat Recovery System

Heat Pump Systems can be up to 30% lower cost than Heat

Recovery Systems e care u no o cross zones; n o as a or pe

o Do not serve both Interior and Perimeter on the Same System

o Each System is a Point of Changeover; Changeover Routineshould be discussed before hand to insure customer buy-in

o Smaller Systems allow for more points of changeover and easier

retrofits Heat Pumps are typically used for Cool Only Applications

Heating Operation Mode can be locked using Dip Switch Settingsor with Controls


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VRF Design Pitfalls Cool Only Zones

Heat Recovery: Establishing Cooling Only Zones Comfort Cooling and Process Cooling

Process Cooling

Do you really want your 2 Ton Server Room on your 20 TonHeat Recovery System? Think about your House VAV, CW

o Benefit: Can Potentially Recover Heat Absorbed in Process Areao Benefit: Less Equipment

For Colder Ambient Climates, add BSVQ as PRD

Not a given; Each Design and System is Unique

What if majority of Comfort Zones are Interior? After Hours?

o Cons: Significant Additional Run Hours on Expensive HouseSystem

Would a separate Split System, VRF, or RTU with Economizerbe a better option with VRF Fan Coil as backup only?


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VRF Design Pitfalls Cool Only Zones

Heat Recovery: Establishing Cooling Only Zones Comfort Cooling and Process Cooling

Comfort Cooling

Is the Makeup Air Tempered or does the Design incorporate

Heat Reclaim Ventilation? If so, ventilation loads are fully or

present for certain occupied zones.

Potential for Design without Point of Heat/Cool Changeover

o Design can eliminate BSVQ Box and save costs, reduce units

o With VRF technology, the Expansion Valve can shut in Coolingso that there is no Coil Capacity when satisfied

o This is quite different from the typical Single Duct VAV

installation


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Single Floor Office Example

The most cost effective way is to design around heat pumps, right?

This project consists of 4 main heat cool changeover zones

This would mean 3 VRV heat pump outdoor units & a Split System

Approximate VRV Installed Cost = 100% (this will be used as the baseline cost)

A heat recovery system best suits this project as one outdoor unit can be utilized to match the loads

Does this mean we can now connect the server room to the VRV system?

No, this should be connected to a single split system (this is true of all VRV/VRF systems!)

o A VRV indoor unit can however be used as a back up

*


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Eliminating Unnecessary BSVQs reduces costs and equipment

Just Branch off Liquid and Suction Main Only

BSVQ

36

BSVQ

60BSVQ

0


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VRF Design Pitfalls - Controls

Zone Controller Application and Misconceptions

Zone Controller is Not Necessary

o Yes, Control can be strictly centralized

o However, it is Better to use a Zone Controller (Service Functions)

Functionality can be restricted from the Centralized Device

o BAD Idea: Trying to use 3rd Party Zone Controls

This is possible and has been done successfully

o Most Instances required additional coordination

Unnecessary Costs; Requires Skilled Programmer

Zone Controller is Point of Temperature Sensing

o Not Always the Case; This is Configurable on Some models

Grouping Fan Coils onto a Common Point of Zone Controlo Simplifies Control and Eliminates Unnecessary Costs

o Considerations: How to View at Central Level, How to Sense andReport Zone Temperature for Control and Monitoring Purposes


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VRF Design Pitfalls - Controls

Centralized Controller. The Best Money you ever spent. Is a Separate BAS even required? It really depends.

o 3rd Party BAS is very costly especially if full control integration isrequired

o Can a Central Controller provide enough functionality?

3rd

Party Equipment Start/Stop Scheduling, Status, Interlocks en ra on ro er s es gne y qu pmen anu ac urer so

you get all the controllable points and some basic routines

If a requirement, what functions should 3rd party BAS provide?

o Scheduling, Monitoring Only? Custom Routines? Interlocks?

Centralized Controllers can provide many beneficial features Zone Controller Restrictions, More Custom Changeover

Routines, Remote Monitoring/Control and Alarm Reporting


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Other Things to Watch Out For When Designing A

VRV Solution

Things that can lead to Poor Comfort Poor zoning

Over connecting capacity to an outdoor unito Is there diversity in the building?

Wrong type of indoor units

Over sizin units oor tem erature control

Return air sensor positiono Is outside air integrated to the indoor unit?

Things that can lead to a Project going Over Budget

Too many, or wrong indoor unit type. Too many zones on heat recovery unit

Oversized units


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Questions


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VRF Systems: The


Hwakong Cheng

Senior Mechanical Designer

Taylor Engineering, LLC



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Designer Perspective

Agenda System Selection Zoning and system layout Pipe Sizing and Layout

Refrigerant Management


Code Compliance Controls Integration

Limitations Photos


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System Selection

Ducted vs Ductless(but still need ventilation)

Heat Pum vs Heat


Recovery Systems

Air vs Water-cooledcondensing units


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Heat Pump System Type



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Simultaneous Heating & Cooling

Cool Morning


N


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Simultaneous Heating & Cooling

Cool Afternoon


N


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Pipe Sizing and Layout

Pipe length, effective pipelength, vertical height, and

overall system pipe length

limitations

Reduced capacity with longer


Prescriptive pipe sizing from

manufacturer (selection

software)


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0


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Pressure testing



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VRF lots of refrigerant

ASHRAE Stds 15/34, CMC Ch 11

R-410A: Safety group A1

25 lb / 1000 cubic feet410



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Example:

Ductless fan coils operable

windows

System charge: 48.3 lb R410A

Normal room: 16x15x10 = 2400 cf


Smallest room: 16x10x10 = 1600 cf

Catastrophic discharge into

smallest room:

48.3 lb / 1600 cf = 30.1 lb / 1000 cf

Above limit of 25 lb / 1000 cf!


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Possible solutions:

Permanent openings

Door louver/undercuts

Transfer air grilles

Transfer fan


Connected duct systems


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LEED EAc4 Enhanced Refrigerant Management

R-410 high global warming potential GWP =1890(GWP of CO2 = 1)

Look at: Lbs/ton, GWP, leakage rate, lifespan

LEED Credit EAc4 difficult to achieve


Refrigerant in rated corridors


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Coordination with other trades

Electrical power to each:

fan coil

branch controller / branch selector

condensing unit

Plumbin :


condensate from eachfan coil, branchcontroller

may be over sensitive

ceilings, electricalequipment

piping may need to besloped


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Code Compliance

24 ( 6)

1230


/


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Controls Integration

Stand-alone controls

Scheduling

Setpoint control

Monitoring / Feedback

Web access


BMS system integration

BACnet/LonWorks


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Limitations

Humidity control

Fan pressure

Limited control of airside pressure drop

Watch PD for ducted systems

Standard filters ~ MERV 4


Sound


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Limitations

Airside Economizer

35

40

45

110

120

130

140

150

160

170

Hu

35

40

45

120

130

140

150

160

170

H


Weather Hours

0 to 1

0 to 1

0 to 1

0 to 1

0 to 1

0 to 1

0 to 1

0 to 1

0 to 1

-10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110

0

5

10

15

20

25

30

Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com

10

20

30

40

50

60

70

80

90

100


idityRatio,grains/lbofdryair

Dry-Bulb Temperature, F

NOYES

Return Air

Supply Air

Return Air

Supply Air

Weather Hours

117 to 105

104 to 92

91 to 79

78 to 66

65 to 53

52 to 40

39 to 27

26 to 14

13 to 1

-10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110

0

5

10

15

20

25

30


10

20

30

40

50

60

70

80

90

100


umidityRatio,grains/lbofdryair

Dry-Bulb Temperature, F

Return Air

San Francisco

Weather


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Limitations

Airside Economizer

aftermarket option forducted systems



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Photos



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Photos



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Questions



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VRF Systems: The


Tal Rabiah, PE

Physical Planning & Construction

UC Santa Cruz



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Overview

1. Existing Installations

2. Pros and Cons

3. Outdoor

4. Indoor


.

Plumbing

HVAC

Maintenance

Design


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1. Existing Installations (past 7 years)

University of Michigan (Ann Arbor, MI)

N. Campus Recreational Sports Building

o 2-story building; 32 tons

Central Campus Printing Building



Central Campus Recreational Building



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1. Existing Installations (past 7 years)

University of California-Santa Cruz

Communication Building

o Cell phone areas; 16 tons

Communication Building

o Computer areas; 16 tons


UC Santa Cruz Extension

o Santa Clara Computer Labs; 8 tons


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2. Pros and Cons of VRF Systems

Pros:

A VRF system is possibly more suitable for coolingupgrades in existing buildings than chilled water system

since the VRF has less than 1/4th the pipe size. The VRF

system may even be a preferable alternative to the

extension of an existin chilled water s stem to a new


building or building addition.

VRF is possibly the best option for systems with fewer than100 tons of cooling capacity.


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Pros (con't) :

The new 100% outside air fan coil unit for VRFs is asignificant advancement in the application of VRF system

in make-up air and laboratory HVAC applications where

100% outside air is required.


simpler to design, operate and maintain by eliminating

cooling tower, boiler, pumps and chemical treatment.


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Pros (con't) :

VRF offers simultaneous cooling and heating on the samepiping network through the use of heat pump and heat

recovery systems with automatic changeover.

All brazed cooper piping system for more corrosion and


.

Long refrigerant piping lengths to accommodate manytypes of applications.


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Pros (con't) :

Low operating sound levels-58 dB at full load for outdoorunit and 25dB for indoor unit.

Water balancing is eliminated and air balancing issimplified.


u a e or cre s on energy e c ency an ecompliant.

Capacities are AHRI certified.


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Cons: VRF is a proprietary system. Mixing of parts from different

VRF manufacturers is not possible.

Operates at 530 psig which is considered very highpressure piping system inside a building, which makes leak


.

Is suitable for certain heights and sizes of buildings.


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Cons (con't) : Occupancy sensors are not provided as part of the

system.

Maintenance accessibility for Branch Selectors andBranch Controllers is required.


an on y e ns a e an ma n a ne y ra nepersonnel.

Few manufacturers are available which leads to lessercompetition.


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Cons (con't) : System lifetime is not yet as predictable as the hydronic

systems.

Is not widely known by U.S. HVAC designers.



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3. Outdoor Installation

For roof installation provide spring-type vibration isolatorswith lateral restraints. Bolt isolators onto a 4 thick

concrete pad and onto bottom of condensing unit.

Do not use wooden or sheet metal roof curbs under

units.


On grade, install unit on a 4 concrete curb with

neoprene or cork isolators bolted to bottom of unit and to

concrete curb.


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Outdoor Installation cont

- Use vibration isolators

Roof: spring-type

Grade: neoprene

Bolt to concrete pad


NO wood curbs

NO sheet metal curbs

Units shall be braced so that they will not


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Units shall be braced so that they will not

laterally tilt due to high winds.


Pi i th h f h ld b


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Piping through roof should be run

through a pipe roof curb with flashing

around it.



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Flexible Connection


When vibration isolators are provided,

provide 6 long flexible braided copper

connector on refrigerant piping that connectsto the unit. Do not bend flexible connectors

excessively.


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Provide a services ball-type shut-off valve

with a charging port at the connection to the

unit.


Insulation refrigeration lines with


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Insulation refrigeration lines with

thick closed-cell foam insulation.


Piping should be supported every 6 feet or


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Piping should be supported every 6 feet or

less without pinching insulation.


H. Follow manufacturers instructions regarding the amount of


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g g

required open space around the units to allow for adequate air

movement.



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Do not allow suspension rods, ducts, or conduits

to touch the piping (to avoid electrolysis).



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Weather coat the outdoor insulation of piping with a

weather-resistant PVC coating. Valves should have

removable and re-installable covers.



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Labeling

Label piping on roof with weather-resistant


pipe labels including directional arrows. Alsolabel condensing units with the equipmentnumbers of the indoor evaporator units thatthey serve. Follow ANSI A13.1 standards.

Clean condenser fins where there is vegetation


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Clean condenser fins where there is vegetation

buildup on the condenser tubing fins.


I d I t ll ti


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Indoor Installation



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Connect the ceiling supported unit to duct through a 4

long flexible connection. Do not allow kinks in the flexible

connection.



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Seismic Supports

See manufacturer instructions

See local codes



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Condensate Waste

Prefer gravity flow

Use a trap

Provide secondary

drain i e


Or: heavy-duty withredundant pump

Connect the ceiling supported unit to duct through a 4


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long flexible connection. Do not allow kinks in the flexible

connection.



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Condensate Drain Pan

Provide drain pan

under unit separate

from the evaporator

unit drain pipe.


If condensate pumps

are used put in drain

pan.

Example of unit discharge ductwork from a


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Example of unit discharge ductwork from a

plenum box.


Assure that filters, unit control panel, and fan


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, p ,

motor are all easily accessible for periodic

maintenance or replacement.


Recommendations


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Recommendations

Plumbing HVAC

Maintenance

Design


Plumbing Recommendations


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Plumbing Recommendations

Read the fine print with regard to limitations of pipinglength. The length specified is the total equivalent pipe

length.

Confirm pressure testing of pipes at 600 psig for 24

hours.


3. The VRF system typically operates in the 300-400 psig

range, making leak protection essential.

HVAC Recommendations


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HVAC Recommendations

A BacNet or Lonworks device is required to connect theVRF controls to the rest of your building or campus

control system. This device will allow you to monitor the

VRF system, but not control it.

If there are many confined spaces served by the VRF


,

alarms may be required in order to meet ASHRAE

standards 15 and 34.

Maintenance Recommendations


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The VRF system is a complete proprietary packagedsystem, including its own related controls, except for the

refrigerant piping.

You cannot intermix parts from the different

manufacturers of the VRF system.


System maintenance requires an experienced refrigerant

technician who is familiar with applicable codes related to

refrigerants, leak detection, and ventilation requirements.



112/194


When selecting a VRF system for your building, selectcontractors that are trained and qualified to install this

system. Select a contractor who has experience

pressure testing refrigerant piping which has been

pressurized up to 600 psig.


- ,

therefore quality of brazing, evacuating, and pressure

testing can affect the VRF system performance



113/194


Provide easy access to units on roof (not through anaccess hatch or a catwalk).

For the maintenance program, allow inspection of units

every three (3) months.


Design Recommendations


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Design Recommendations

When comparing a VRF system to other air conditioningsystems, compare it to the 4-pipe fan coil system, or to a

water source heat pump system. Keep in mind the

systems lifetime and maintenance costs.

If outdoor installation is within a mile of the ocean, or if


,

coatings on unit exterior finish and on condenser copper

tubing and fans.

Coordinate unit color selection with the architect.

Aesthetics can be especially important at someinstallations.

Questions


115/194

Questions


VRF Systems: The David Sellers, PE, Senior


116/194


VRF Systems: The

Good, The Bad and The

Ugly

The Commissioning

Perspective

Engineer

Facility Dynamics Engineering

NW Satellite Office

www.FacilityDynamics.com

The Commissioning Providers Perspective
http://www.facilitydynamics.com/http://www.facilitydynamics.com/


117/194

Corporate Perspective

Limited VRF Exposure Some Daikin and some Mitsubishi

No tests developed in our

commissioning database

One system designed by a senior

engineer in a past life (about 15years ago in the Air Force)

Several people can hardly wait to

get inside a branch controller/point

of change-over

On person about to take factory

training

Early Commissioning Providers

VRF SYSTEMS: THE GOOD, THE BAD AND THE UGLY; THE COMMISSIONING PERSPECTIVE 2

The Commissioning Providers Perspective


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Personal Perspective

One new construction and oneretrocommissioning project with

Mitsubishi VRF equipment (both

current projects)

Exposure to built up direct

expansion systems since 1976

o Dual mode system serving anice rink in winter and building

loads in the summer (See

Mentoring Field Technicians; A

Learning Experience for

Everyone Involved;

Proceedings - NCBC 2009)

o Various commercial and

process projects

Early Commissioning Providers


Commissioning Process Goals


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New Construction

s

Verify:

Installed performance

Design intent achieved

Enable persistence

o Documentation

Commissioning record

System Manual

o Train the staff

Try not to go crazy

Have fun

Retrocommissioning* (MBCx

program context)

Develop facility baselines

Identify and assess energy

efficiency opportunities

Coordinate with the Owner to

implement improvements

Verify goals are achieved

Enable persistence

Documentation

o Pre and post baseline reports

o Train the staff

Have Fun

A.K.A. Existing Building Commissioning, EBCx, RCx,

Recommissioning, Monitoring Based Commissioning,

Building Tune-up, and, when I first started, operating the

building properly


Typical Issues


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Cx/EBCx

Access/Serviceability

Occupant satisfaction

Installation does not comply with

Manufacturer or industry standards

Implementation of complex

technology difficult to achieve inreal world environments

Installation does not reflect design

intent

Integration

Optional/2nd party equipment Other HVAC processes

Control systems

Persistence

VRF Experience to Date

Access/Serviceability

Occupant satisfaction

Installation does not comply with

Manufacturer or industry standards

Implementation of complex

technology difficult to achieve inreal world environments

Installation does not reflect design

intent

Integration

Optional/2nd party equipment Other HVAC processes

Control systems

Persistence


Access and ServiceabilityDuring Construction


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Access and ServiceabilityAfter Construction


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Simple Constant Volume AHU System Diagram


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VRF System Diagram


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Electronic expansion valve, variable speed

fan, filters, economizer dampers and related

controls above a 10 foot semi-hard ceiling

Ceiling plenum, shafts, and other

building structure provide reliefpath


The Actual VRF System Diagram


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10

To existing constant

volume reheat

zones

Filter Access


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Filter Access Door:Typical access interval

Open once every

6 to 12 months to

change filters


Filter Access


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DDC Panel:Typical rewire and/or

recommission interval

Once every 6 to

12 months if

mounted on filter

access door

Once every 6 to

12 years if

mounted

somewhere else


Branch Controller Technologyhttp://www.mylinkdrive.com/CityMulti/Software/CM_Refrigerant_Flow/


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Image courtesy Mitsubishi Refrigerant Flow

Demonstrator; Used with Permission

13

Branch Controller Technologyhttp://www.mylinkdrive.com


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Image courtesy Mitsubishi PRUY Service

Instruction; Used with Permission

14

Branch Controller Technology

http://www.mylinkdrive.com


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Recommended

access opening

nominally 18 x

18 Small to mediumtechnical person - 20

Image courtesy

Mitsubishi

PRUY Service

Instruction;

Used with

Permission

15

Branch Controller Installed Location


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132/194




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Branch Controller Service Procedures


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Image courtesy Mitsubishi PRUY Service Instruction; Used with Permission

19



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20



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21



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Image courtesy Mitsubishi PRUY Service Instruction;

Used with Permission

22



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Typical service welding equipment



23



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24



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Image

courtesy

Mitsubishi

PRUY

Service

Instruction;

Used with

Permission 25



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Image

courtesy

Mitsubishi

PRUY

Service

Instruction;

Used with

Permission26

Installation Practices


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Refrigerant piping installation practice critical to short and

long term system integrity General requirements no different from those employed

with any built up refrigeration system

Details associated with R410 systems may vary from

standard practice in the field at this point in time

27VRF SYSTEMS: THE GOOD, THE BAD AND THE UGLY; THE COMMISSIONING PERSPECTIVE

Cleanliness Is EssentialCleaned and Capped


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Cleaned to an ASTM

established limit for residue

Purged with dry nitrogen Sealed with rubber plugs with

positive nitrogen pressure

inside the tuber

Continuous nitrogen purge

necessary during installation

Maintains factory cleanedand capped integrity

Prevents contamination by

the oxides and residuals

produce by brazing

Mitsubishi recommendsbrazing temporary caps on

pipes that are not connected at

the end of the day

Used to be Cleaned

and Capped


Cleanliness Is Essential


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Moisture and refrigerant dont work welltogether

Corrosion Ice

Refrigerant oil problems

Motor problems

Cleaned and Capped

Used to be Cleaned

and Capped


Cleanliness Is Essential


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Dirt and precision machinery dont workwell together

Moving parts in compressors Small orifices in metering and control

valves and lubrication system

Chemical reactions with oil andrefrigerant

Cleaned and Capped

Used to be Cleaned

and Capped


Field Joints


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Field joints are made using a frustum of right circular

cone

31

Image

courtesy

Mitsubishi

PRUY

Service

Instruction;

Used with

Permission

Field Joints


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Field joints are made using a 45SAE Flare joint

Operating Pressures

Refrigerant Low Side High Side

R22 55-70 psig 180 - 260 psig

R410 95 - 135 psig 305 - 410 psig

32

Image

courtesy

Mitsubishi

PRUY

Service

Instruction;

Used with

Permission

Field Joints


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Field Joints


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Flaring Tools; Theyre Not All Created Equal
http://www.ridgid.com/ASSETS/BEDAF5C9AC504029A6264034BF58D1D5/458R_Ratchet_Flaring_Tool_3C.jpg


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Conventional flaring tools

press the flare onto the end of

the tube

Recommended flaring tool rolls

the flare onto the end of the

tube


Images courtesy www.ridgid.com/; Used with Permission

Either way: Metal to metal sealing mechanism

Lubricate flare before tightening

Tightening the Connection
http://www.ridgid.com/ASSETS/BEDAF5C9AC504029A6264034BF58D1D5/458R_Ratchet_Flaring_Tool_3C.jpghttp://www.ridgid.com/ASSETS/9F672F49DF3E4A54B01B4361F7D5292B/345_Flaring_Tool_3C.jpg


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Lubricate with a refrigerant compatible oil

Use two wrenches

Use specified torque values


Torque Wrenches, Flare Nut Wrench and CrowsFoot


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Tightening the Connection


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Easier accomplished on the bench than in the air

Factory line sets minimize field flares


Vibration and Stress Relief


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Flare

Flare

Branch controller support per

Mitsubishi requirements

Rigid support nominally with-in

20 per Mitsubishi requirements

Vibration and Stress Relief


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Relative motion still possiblewith out sway bracing

Refrigerant Oil


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R22 systems use mineral oil as a lubricant

R410A systems use an ester oil, either ether oil oralkylbenzene

Using the wrong oil can cause sludge and other problemsleading to failure

Tools use on R22 systems can be contaminated withmineral oil and should not be used on R410A systems

Contamination can lead to sludge and other problems

R410 oil is an order of magnitude more hygroscopic than

R22 oil


Connecting to Existing Branch Controllers


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Concern on the part of the new project contractor

regarding unknown quality of the previous contractorswork

Pipe installation practice

System evacuation and charging practice

Low charge in existing system due to leakage

Near Azeotropic refrigerant compounds the problem


Azeotrope


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A mixture made up of two or more refrigerants with

similar boiling points that act as a single fluid. Thecomponents of azeotropic mixtures will not separate

under normal operating conditions and can be charged

as a vapor or liquid


Definitions from the National Refrigerants web site; http://www.refrigerants.com/frame.htm

Near Azeotrope


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different boiling points that, when in a totally liquid orvapor state, act as one component. However, when

changing from vapor to liquid or liquid to vapor, the

individual refrigerants evaporate or condense at different

temperatures. Near-azeotropic mixtures have atemperature glide of less than 10 F and should be

charged in the liquid state to assure proper mixture (non-

azeotropic) composition



Zeotrope


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different boiling points. Zeotropic mixtures are similar tonear-azeotropic mixtures with the exception of having a

temperature glide greater than 10 F. Zeotropic mixtures

should be charged in the liquid state



Control Sensor Installation

Damper face velocity = 800 fpm


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Damper face velocity 800 fpm

Mixing plenum depth = 39

Do you think the mixed air

Sensor is really measuring

The mixed temperature?


Single Point Mixed Air

Sensor LocationOutdoor

Air

Return

Air

VRF Fan Coil

Dampers

Economizer Outdoor Air Enthalpy Change-over Sensor


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163/194




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Economizer Outdoor Air Enthalpy Change-over SensorAre there any issues with this enthalpy


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y py

sensor installation given:

The duct is the outdoor air duct The sensor is lying

on the bottom ofthe duct,unsecured



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The Improved installationImage courtesy Brian Nixon



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53VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

; THE

COMMISSIONING

PERSPECTIVE

VRF Unit Economizer Design Intent

Provide an economizer cycle Position to full return air if the VRF


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Provide an economizer cycle

No mechanical cooling until the

economizer is on 100% outdoor air(Code requirement; integratedeconomizer)

Supplement the outdoor air coolingas required (Code requirement;integrated economizer)

Continue to use outdoor air until theoutdoor air is not suitable for cooling(Code requirement; integratedeconomizer)

Use minimum outdoor air if theoutdoor air enthalpy is not suitablefor cooling (Code requirement;

integrated economizer) Do not heat until the economizer is

on minimum outdoor air (i.e. nosimultaneous heating and cooling)

Position to full return air if the VRFsystem is off (critical given the OA

source) Use no outdoor air in warm-up mode

if the space is not occupied

Use outdoor air in the cool-downmode only if outdoor air is suitablefor cooling

Minimum outdoor air flow matchescontract document requirements forminimum occupancy and maximumoccupancy

The demand controlled ventilationsystem can over-ride thetemperature based control of the

economizer cycle if necessary tomaintain adequate ventilation.

VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

; THE

COMMISSIONING

PERSPECTIVE

54

Design Intent Documentation

R i d th VRF it h d l


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Required accessory on the VRF unit schedule

Code compliance required

Economizer supplier uses Honeywell W7212 which:

Can perform integrated economizer cycle (but also can doa non-integrated economizer cycle

Can do warm-up/cool down if configured properly

Can close the dampers when the system is off if configuredproperly

Can do either/or demand controlled ventilation cycle

o Minimum occupancy air flow if CO2 below threshold

o Maximum occupancy air flow if CO2 above threshold

55VRF SYSTEMS

: THE

GOOD

, THE

BAD AND

THE

UGLY

; THE

COMMISSIONING

PERSPECTIVE

Design Intent Documentation vs. Intent

Provide an economizer cycle Position to full return air if the VRF

Covered by Documents


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y

No mechanical cooling until the

economizer is on 100% outdoor air(Code requirement; integratedeconomizer)

Supplement the outdoor air coolingas required (Code requirement;integrated economizer)

Continue to use outdoor air until theoutdoor air is not suitable for cooling(Code requirement; integratedeconomizer)

Use minimum outdoor air if theoutdoor air enthalpy is not suitablefor cooling (Code requirement;

integrated economizer) Do not heat until the economizer is

on minimum outdoor air (i.e. nosimultaneous heating and cooling)

system is off (critical given the OA

source) Use no outdoor air in warm-up mode

if the space is not occupied

Use outdoor air in the cool-downmode only if outdoor air is suitablefor cooling

Minimum outdoor air flow matchescontract document requirements forminimum occupancy and maximumoccupancy

The demand controlled ventilationsystem can over-ride thetemperature based control of the

economizer cycle if necessary tomaintain adequate ventilation.


Covered by Code

Covered by Code

Covered by Code

Covered by Code

Covered by W7212 if Implemented



Covered by Documents; Probably

requires TAB RFI to clarify


Economizer Procurement

VRF Fan coil unit provided by Economizer mixing box


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VRF Fan coil unit provided by

1st party

Includes wiring harness for

economizer interface

Economizer package provided

by 2nd party

Includes generic wiringdiagram

Capable of a number of

change over strategies

Economizer mixing box and

controls provided by a 3rd party

Includes multiple product

specific data sheets with a

wide range of capability

Economizer mixing box

installed by a 4th party

Economizer controls installed

by a 5th party

Economizer must interface to a

building wide automation

system by a 6

th

party to dodemand controlled ventilation

Verification of design intent by

a independent 7th party


The Result: The Economizer Doesnt Work

Conf sion regarding the pre f nctional testing


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Confusion regarding the pre-functional testing

requirements Must reference:

Contract documents (contractor charged with developingand executing start-up and functional tests with spot

checks by the Cx provider after completion) Economizer package documents (generic in nature)

Economizer controller documents (product specific innature but no project specific details)

Control system submittals (retransmits demand controlledventilation signal and BACnet interface)

California energy code (very thick book)


Generic Economizer Package Documents


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No wiring or check out information in one set of instructionsbut a lot of product specific information

Generic wiring and a cut and paste check out procedure in adifferent set of instructions but no product specific information

Both use a clicks on economizer change over switch as abasis of design



In the normal Berkeley


175/194

In the normal Berkeley

climate, it would be

possible for a clicks-onwith the tolerances

shown to disable the

economizer in the

afternoon of the first day

of August and not re-enable it until September

some time

60


There are many days in


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There are many days in

many other months were

the same thing couldhappen (the light green

band on the graphs is

the normal range)

61

Product vs. Project Specific Wiring Information


177/194

62

Honeywell documentation includes wiring diagrams for 9

applications None are Mitsubishi systems

None are VRF systems 2010 Honeywell International Inc.; Used with permission



178/194

63


volume reheat

zones

Outdoor air provided by an economizerequipped constant volume reheat system

VRF zones are variable volume and require

system control strategy change

VRF zones potentially interactive with each

other and constant volume zones

Must balance economizer benefits with

reheat penalty

VRF dampers currently not interlocked to

close with VRF shut down

Conflicting Sensor Location Information

Discharge air vs mixed air


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Discharge air vs. mixed air

Either will work but discharge airlocation will cause the

economizer to generally

function like a non-integrated

economizer

Bad for maximizing energysavings

Good for compressorreplacement costs in

packaged equipment with

limited or no turn-downcapability


2010 Honeywell International Inc.; Used with permission

Economizer Controller to VRF Control Integration

W7212 designed


180/194

g

to interlock with

the mechanicalcooling and keep

it off until the

economizer has

a chance to work

Economizerpackage wiring

diagram shows

no interlocks

Field wiring for

intelock is there,but wheres it

going?


Economizer Controller to VRF Control Integration

W7212 is


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capable of a

warm-up andcool-down cycle

(design intent)

but currently is

not wired for it




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67


volume reheat

zones

Main AHU schedules are provided by thebuilding wide control system

VRF schedules are provided by the VRF

control system

Currently no communication of schedules

between the two systems

Occupant Satisfaction


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Space temperature

drifts up 2F in about 1

hour and 30 minutes

then is

driven

back down

2F below

set pointin about

20

minutes

Three out of four

zones sampled at

random so far are

doing this



184/194


Meanwhile the pneumatic and chilled

water technology that is being replacedby the VRF systems floated around with-

in the throttling range of the controller

during the same time period Two out of two

pneumatic zones

sampled atrandom were

working this way

Throttling Range

Technology Can Have its Limitations

VRF systems have turndown capability but not below


185/194

VRF systems have turndown capability but not below

about 20-25% of capacity Subject to issues related to over-sizing just like any

other approach

If the peak load potential in a zone is unknown, thenyou know what you dont know

o Consider the minimum load potential

Seasonal load profile

Daily load profile

o

Address the current reality with provisions for thefuture potential

o Make sure you understand the details of thetechnology you are about to embrace




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Comfort aside, this could

be costing energy in the

form of unnecessary

dehumidification

Note room dew point

dropping below

outdoor air dew point

The Machinery Can Be Made to Work


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But it Requires Attention to Detail


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And Taking the Time to Integrate Things


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Integration; The Commissioning Perspective

Integrate the equipment into a

working system


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working system

Verify design intent in the shortterm

Ensure its persistence in the

long term

Integrate all the players into a

team to identify and solve

problems

Bring new technology into the

mainstream

Understand how it should work Address prototypical issues

Ensure it things keep working

for the life of the systemEarly Commissioning Providers


National Refrigerantswww.refrigerants.com


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76

Principles of Refrigeration by Roy Dossat

Complex principles in understandable terms


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Trane Refrigeration Manual

Other Resources


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http://www.trane.com/Commercial/Dna/View.aspx?i=492 Copeland Refrigeration Manual

http://www.emersonclimate.com/en-us/brands/pages/copeland.aspx

http://lvhvac.com/cope_bulletins/aeIndex.pdf

Sporlan Valve

http://www.sporlanonline.com/literature.shtml

Mueller Brass

http://www.muellerindustries.com/

ASHRAE Journal

Variable Refrigerant Flow Systems by William Goetzler, April 2007;www.ashrae.org


Questions
http://www.trane.com/Commercial/Dna/View.aspx?i=492http://www.emersonclimate.com/en-us/brands/pages/copeland.aspxhttp://lvhvac.com/cope_bulletins/aeIndex.pdfhttp://www.sporlanonline.com/literature.shtmlhttp://www.muellerindustries.com/http://www.ashrae.org/http://www.ashrae.org/http://www.muellerindustries.com/http://www.sporlanonline.com/literature.shtmlhttp://lvhvac.com/cope_bulletins/aeIndex.pdfhttp://www.emersonclimate.com/en-us/brands/pages/copeland.aspxhttp://www.trane.com/Commercial/Dna/View.aspx?i=492


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VRF Systems presentation

Documents

Transcript of VRF Systems presentation