hvac_units_for_the_replacement_of_wall_hung_units__11_15_2012.pdf

8/14/2019 HVAC_Units_for_the_Replacement_of_wall_hung_units__11_15_2012.pdf

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HVAC SYSTEMS FOR THE REPLACEMENT OF EXISTING WALL

MOUNTED AND INDOOR CABINET TYPE CLASSROOM UNITS

Prepared for the

Los Angeles Unified School District

Facili ties Services Divis ion

November 15, 2012

By

Maroko & Shwe, Inc., Professional Engineers

1106 B, West Magnolia BoulevardBurbank, CA 91506

(818) 840-0280

[email protected]

www.marokoshwe.com


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11/ 15/ 2012 Replacement of wall mounted and indoor cabinet units

1

Maroko & Shwe, Inc., 1106-B W. Magnol ia Blvd., Burbank, CA 91506Tel: (818)-840-0280 Fax: (818) 840-0284 e-mail: [email protected]

Table of Contents

Executive Summary PAGE

Introduction 3

Methods 5

Comparative Statements 9

Conclusions 11

Recommendations 11

Decision Tree 12

Individual system description and evaluations PAGE

Rooftop Gas Electric Units 13

Rooftop Heat Pumps 18

Split gas electric systems 18

Split system heat pumps 19

Variable refrigerant flow 27

New Generation Wall mounted heat pumps 31

New Generation Indoor cabinet type heat pumps 38

4 pipe Hydronic fan coils 41

Chilled Beams 45

LG Installation @ Grant School 49

Typical System Layouts

Rooftop Gas Electric Units Fig 3, Page 14

Rooftop Heat Pumps Fig 3, Page 14Split System Heat Pumps Fig 3, Page 14

Split System Heat Pumps Fig 14, Page 24

Split System Heat Pumps Fig 18, Page 30


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Variable refrigerant flow Fig 17, Page 29

New Generation Wall mounted heat pumps Fig 22, Page 34

New Generation Indoor cabinet type heat pumps Fig 26, Page 39

Chiller Boiler Plant for4 pipe Hydronic fan coils Fig 30, Page 44

Chil led Beams Fig 34, Page 47

Appendices

A. Sample EnergyPro Calculation Results

B. Previous related studies

1. HVAC Systems Acoustical, Cost and Energy Study, June 6, 2005

2. Duct Free Split System Heat Pumps as Alternative for Wall Mounted Heat PumpsIn existing classrooms, March 21, 2005

3. Measured Classroom Sound Levels, May 30, 2005

C. Catalog data

Rooftop Gas Electric Units C 1

Rooftop Heat Pumps C 8

Split system heat pumps C 16

Variable refrigerant flow C 28

New Generation Wall mounted heat pumps C 34

New Generation Indoor cabinet type heat pumps C 39

4 pipe Hydronic fan coils C 49

Chilled Beams C 60

Air Cooled Chi llers C 63

Boilers C 69

Pumps C 71

Expansion Tanks C 73


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EXECUTIVE SUMMARY

Introduction

This study was initiated to explore the HVAC systems that can be used to replace the agingwall mounted and indoor cabinet type heat pump units in existing schools.

The following factors will be compared:

1. Overall cost effectiveness

a. Initial installation cost

b. Energy cost

c. Maintenance cost.

2. Indoor environmental conditions

a. Outdoor air ventilation

b. Air filtration

c. Air movement

d. Temperature

e. Humidity

f. Sound level

3. Aesthetics

a. Indoor

b. Outdoor

4. Difficulty of installation

a. Space requirements

b. Architectural modifications required

c. Structural modifications required

5. Complexity of system

6. Difficulty of maintenance

a. Service assistance from manufacturer


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b. Parts availability

7. Reliability from past experience

8. Durability from past experience

9. Installation time requiredThe most suitable system will be identified for each prevalent type of existing classroombuilding.

Please be aware that the performance and maintainability is dependent not only on justsystem type and manufacturer but also on the system design and installation. Theinstallation arrangement of each system will be clearly defined in the report.

The following building types will be included:

1. Single story building of wood or metal frame construction with single loaded corridor andsloped roof. The finger schools, two room bungalows, re-locatable classrooms and

portable classroom buildings have similar envelope configurations and thus similarthermal performance. They will be grouped under this category and studied together forenergy performance.

2. Two story building of concrete construction with double loaded corridors and flat roof.The concepts for multistory buildings will be similar.

Typical HVAC system layout drawings for each system will be provided.

The following HVAC systems will be included:

1. Rooftop Packaged Gas / Electric Units

2. Rooftop Packaged Heat Pumps

3. Split gas electric systems (Gas furnaces with outdoor condensing units. Report only. Noenergy studies will be made as this is not going to be installed in the future.)

4. Split system heat pumps

5. Variable Refrigerant Flow Systems

6. New Generation of wall mounted heat pumps

7. New Generation of indoor cabinet type heat pumps

8. 4 pipe fan coil units with air cooled chillers and gas fired boilers

9. Chilled beams with dedicated outdoor air systems

A technical comparative statement will be provided so that the significant information can becompared conveniently at a glance.


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The following related studies that were previously done for LAUSD will be attached asreferences:

1. HVAC Systems Acoustical, Cost and Energy Study, June 6, 2005

2. Duct Free Split System Heat Pumps as Alternative for Wall Mounted Heat Pumps

In existing classrooms, March 21, 2005

3. Measured Classroom Sound Levels, May 30, 2005

The information in the above studies will not be repeated in the current study.

The reference studies are directed more towards new construction whereas the emphasis of thecurrent study is on existing facilities.

Methods

Energy Use and CostEnergy use estimations will be done with EnergyPro Version 5.1 software. The calculations willbe done for each building type with each of the eight HVAC systems.

Each building will be rotated with the front facing eight different directions and the loadcalculations will be done for each direction. The worst case will be chosen as the basis of thestudy. Since two building types, a 2 story classroom building and a 2 classroom bungalow, areto be studied, a total of 16 different EnergyPro calculations will be made as the first step todetermine the orientation with the highest cooling load.

The input data for the highest load orientation of each building type will be then used tosimulate the annual energy use with each system type studied as the second step. A total of16 different EnergyPro calculations will be made for each climate zone. Energy useestimations will then be done for each system for the three prevalent local climate conditions inthe areas served by LAUSD, the coastal, central LA and valley regions. A total of 48 differentEnergyPro calculations will be made for step two.

Energy cost estimations will be done using both LADWP and SCE rate structures. Theresulting energy costs will be tabulated and presented in the technical comparative statements.This requires an additional 48 EnergyPro runs.

A total of 112 EnergyPro calculations are made for this report.

With reference to the ASHRAE 90.1 Users Manual, energy cost budget calculations are onlyintended to provide a fair method of comparison between different designs and systems butnot to predict actual energy consumption as variations such as occupancy, maintenance,weather conditions, etc. may differ widely.


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Installation Cost

Installation cost will be based on the schedule of values of recently completed similar projectsin the Los Angeles area in the last 5 years, as the cost of the architectural, structural, electricaland plumbing improvements are also required to be taken into consideration. The costs varywidely for the same type of system due to differences in building type and configuration,

asbestos abatement, quality of the construction documents, etc. The values used are averagevalues filtered through our best judgment.

Equipment budget cost quoted by the manufacturers and overall mechanical system costbased on the 2012 Means Cost Data will also be included as reference.

The cost for the wall mounted heat pump will not include the architectural, electrical andstructural. The reason is the study is based on the assumption that a wall mounted heat pumpalready exists and it is to be replaced because it is old and the replacement unit will not requirestructural, electrical and architectural modifications. This is only true for Bard who has anadaptor curb. We have this assumption stated in bold on item 4 of the conclusions on page 11.

Payback Calculations

The calculations will be simple payback.

Example follows comparing Wall Mounted against a Rooftop Unit in the Valley:

Energy Cost per Sq. Ft. Per Year with Rooftop Unit = $ 2.13

Area of studied classroom = 840 Sq. Ft.

Energy Cost per sq. Ft. Per Year per classroom = $ 2.13 X 840 = $ 1789.2

Energy Cost per Sq. Ft. Per Year with Wall Mount = $ 2.33

Area of studied classroom = 840 Sq. Ft.

Energy Cost per sq. Ft. Per Year per classroom = $ 2.33 X 840 = $ 1957.2

Energy Cost Savings Per Year Per Classroom = $ 168

Cost of roof top unit installation per classroom = $ 32,000

Cost of wall mount unit installation per classroom = $ 14,000

Additional cost = $ 18,000

Payback years just on energy savings = 18,000 / 168 =107.1 years

If it is a new installation, the cost of the wall mount could increase to $ 24,000. Then thepayback will be 8,000 / 168 = 48 years.


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Maintenance Cost

Reliable maintenance cost data for different systems is not available in the industry. The easeof maintenance on a scale of 1 to 10 with 10 being the easiest, derived from the opinions ofmanufacturers, installers and service personnel will be used as a means of comparison. Themanufacturers service manual will be used as an indicator of the difficulty of service.

Complexity of Installation

The ease of installation on a scale of 1 to 10 with 10 being the easiest, derived from theopinions of manufacturers, installers and service personnel will be used as a means ofcomparison. The manufacturers installation manual will be used as an indicator of the difficultyof installation.

Complexity of Operation

The ease of operation on a scale of 1 to 10 with 10 being the easiest derived from the opinionsof manufacturers, installers and service personnel will be used as a means of comparison. The

manufacturers operation manual will be used as an indicator of the difficulty of operation.

Indoor Environmental Conditions

All the systems included can accommodate MERV 8 efficiency air filters and also maintain theindoor temperature comparatively well but air distribution effectiveness and expected indoorsound levels differ. The latter will be used to compare indoor environmental conditions.

Aesthetics

Both indoor and outdoor visual obtrusiveness will be reported in either drawing or pictorialformat. A scale of 1 to 10 with 10 being the least objectionable derived from the opinions ofschool personnel, architects, manufacturers, installers and service personnel will be used as ameans of comparison.

Reliability and Durability

A scale of 1 to 10 with 10 being the most reliable or durable, derived from the experience andopinions of installers and service personnel will be used as a means of comparison.

Construction Duration

The time to install a complete system including architectural and structural upgrades will beused as a means of comparison. The labor costs from the Means Cost Estimation Handbookwill be provided as a reference.

The recorded construction durations also tend to vary widely for the same type of system dueto differences in building type and configuration, asbestos abatement, quality of theconstruction documents, management, etc. The values used are average values filteredthrough our best judgment.


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A min imum of three opinions f rom each source w il l be co llected and evaluated basedon our judgment and experience.

The following organizations provided the above required inputs and opinions. This documenthas been circulated for review and comment :

Manufacturers Representatives

1. Benoist Corp: Team Air Enclosures ; Eric Quandt ;[email protected]; 888-236-6478 Office; 818-326-8717 cell; www.benoistco.com

2. Geary Pacific Corp: Bard Wall Mounted Heat Pumps; Maury Tiernan;[email protected]; 714 202-4541 Office; 714 270-7198 Cell;www.gearypacific.com; www.bardhvac.com

3. Sigler Corp: Carrier; Jim Parker; (951) 255-2926;[email protected]

4. Norm S. Wright / AireLink: LG, AireDale; Kent Kung; 714-238-6870;[email protected]

5. U.S.Air Conditioning Distributors: York, Mitsubishi; Karine Leblanc;ASHRAE Region X Assistant Regional Chair; O 626-854-4611; C 310-420-7066

Installation and Service Contractors

1. Comfort Systems USA: Service contractor for LA Fitness & Equinox Health Clubsand Ross Stores; COMFORT SYSTEMS USA. SOUTHWEST DIVISION;909-390-6677; [email protected]; www.csusasw.com

2. Mechanical Technology Systems Inc.: Installing contractor for Dorsey High Schoolexpansion; Russ Hickey; (714) 538-8036;

3. Modern Air Conditioning: Installing Contractor for E.L.A. High School # 2;Fred Hatch; [email protected]; (310) 325-3712


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Comparative Statements

2 Story Building Overall Comparison

(Applicable to typical multistory bu ildings)

2 Story Build ing Energy Cost in 3 different climate zones under LAUSD

(Applicable to typical multi-story buildings)

System

Full Load

Energy

Efficiency

EER

Energy Cost

(1)

Installed

Cost

Ease of

Installation

Ease of

Operation

Ease of

Maintenance

Indoor

Sound

Outdoor

Sound

Indoor Air

MovementAestheti cs Reliabi li ty Durabi li ty

Installation

time

$ / SQ.FT./

Year$

Scale of

1 to 10

Scale of

1 to 10

Scale of 1

to 10dBA dBA

Scale of

1 to 10

Scale of

1 to 10

Scale

of 1 to

10

Scale

of 1 to

10

Days

Rooftop Gas Electric 12.8 2.13 32,000 9 10 10 45 78 10 2 10 10 5

Rooftop Heat Pump 12.8 2.11 32,000 9 10 10 45 78 10 2 8 10 5

Split System Heat Pump 12.5 1.95 20,000 8 10 8 42 74 7 8 7 9 3

Variable Refrigerant Flow 11.6 1.46 30,000 6 9 6 42 62 7 8 6 6 5

Wall mounted heat pumps 11 2.33 14,000 10 10 8 45 78 6 1 8 9 1

Cabinet type heat pumps 9.3 2.27 30,000 8 9 7 48 60 6 6 5 8 2

4 pipe hydronic fan coils 10.1 2.62 32,000 4 4 4 42 110 7 8 4 7 30

Chilled Beams 10.1 2.39 52,000 2 2 4 40 110 10 10 3 7 30EER = Energy Efficiency Ratio (BTU of cooling / Watt of electrical energy consumed)

dBA = A Scale weighted Decibels

(1) Based on LADWP Schedule A-2B TOU with San Fernando Valley weather

Coastal Central LA San Fernando Valley

System Energy Cost (1) Payback (2) Energy Cost Payback (2) Energy Cost Payback (2)

$/SQ.FT./Year Years $/SQ.FT./Year Years $/SQ.FT./Year Years

Rooftop Gas Electric 1.84 93 2.16 214 2.13 107

Rooftop Heat Pump 1.86 102 2.16 214 2.11 97

Split System Heat Pump 1.75 22 1.93 55 1.95 19

Variable Refrigerant Flow 1.34 26 1.47 32 1.46 22

Wall mounted heat pumps 2.07 Base 2.06 Base 2.33 Base

Cabinet type heat pumps 2.16 No Payback 2.31 No Payback 2.27 317

4 pipe hydronic fan coils 2.35 No Payback 2.6 No Payback 2.62 No Payback

Chilled Beams 2.13 No Payback 2.37 No Payback 2.39 No Payback

(1) Based on LADWP Schedule A-2B TOU

(2) Based on 840 square feet floor area classroom


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1 Story Building Overall Comparison

(Applicable to typical single story build ings inc luding relocatables)

1 Story Build ing Energy Cost in 3 different climate zones under LAUSD

(Applicable to typical single story build ings inc luding relocatables)

System

Full Load

Energy

Efficiency

EER

Energy Cost

(1)

Installed

Cost

Ease of

Installation

Ease of

Operation

Ease of

Maintenance

Indoor

Sound

Outdoor

Sound

Indoor Air

MovementAesthet ic s Reli abi li ty Dur abi li ty

Installation

t ime

$/SQ.FT./Year $Scale of

1 to 10

Scale of

1 to 10

Scale of 1

to 10dBA dBA

Scale of

1 to 10

Scale of 1

to 10

Scale of

1 to 10

Scale of

1 to 10Days

Rooftop Gas Electric 12.8 1.92 32,000 9 10 10 45 78 10 2 10 10 5

Rooftop Heat Pump 12.8 1.86 32,000 9 10 10 45 78 10 2 8 10 5

Split System Heat Pump 12.5 1.71 20,000 8 10 8 42 74 7 8 7 9 3

Variable Refrigerant Flow 11.6 1.31 30,000 6 9 6 42 62 7 8 6 6 5

Wall mounted heat pumps 11 1.88 14,000 10 10 8 45 78 6 1 8 9 1

Cabinet type heat pumps 9.3 1.95 30,000 8 9 7 48 60 6 6 5 8 2

4 pipe hydronic fan coils 10.1 1.88 32,000 4 4 4 42 110 7 8 4 7 30

Chilled Beams 10.1 1.45 52,000 2 2 4 40 110 10 10 3 7 30

EER = Energy Efficiency Ratio (BTU of cooling / Watt of electrical energy consumed)

dBA = A Scale weighted Decibels

(1) Based on LADWP Schedule A-2B TOU with San Fernando Valley Climate Data

Coastal Central LA San Fernando Valley

SystemEnergy Cost

(1)

Payback

(2)Energy Cost

Payback

(2)Energy Cost

Payback

(2)

$/SQ.FT./Year Years $/SQ.FT./Year Years $/SQ.FT./Year Years

Rooftop Gas Electric 1.45 143 1.71 165 1.92 No payback

Rooftop Heat Pump 1.53 214 1.71 165 1.86 1,071

Split System Heat Pump 1.34 25 1.54 24 1.71 20

Variable Refrigerant Flow 1.16 41 1.3 35 1.31 33

Wall mounted heat pumps 1.63 Base 1.84 Base 1.88 Base

Cabinet type heat pumps 1.48 26 1.76 238 1.95 No Payback

4 pipe hydronic fan coils 1.62 No Payback 1.87 No Payback 1.88 No Payback

Chilled Beams 1.45 No Payback 1.7 No Payback 1.51 No Payback

(1) Based on LADWP Schedule A-2B TOU

(2)Based on 840 square feet floor area classroom


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Conclusions

1. The VRF type systems are found to have the lowest operating cost.

2. The split system heat pumps are second lowest in operating cost and also secondlowest in installation cost after the wall mounted heat pumps.

3. The conventional split system type heat pumps are more cost effective and easier toinstall, operate and maintain than the VRF systems.

4. The new generation wall mounted heat pumps are significantly improved in energyefficiency and acoustical performance. They could be the most cost effective forreplacement of an existing wall mount unit and are still a viable option where aestheticsare acceptable.This reasoning is true only if the physical size and configuration ofthe unit has not changed to require structural and architectural modifications.

5. The systems that require central chilled and hot water plants are neither cost effective noreasy to operate and maintain.

Recommendations

1. For buildings with flat roofs and parapets, rooftop gas electric units should be the firstchoice for ease of maintenance if M & O prefers.

2. If an existing gas supply does not exist, consider rooftop heat pumps.

3. Use split system heat pumps if the existing roof structure or shape will not support therooftop units.

4. Install the fan coils of the split systems inside pre-manufactured cabinets foracoustical performance, aesthetics and protection from vandalism in lieu of above theceiling. Substantial cost savings can also be realized from not having to reconfigureexisting electrical and data conduits and fire sprinkler piping if the ceiling is notreconfigured.

5. If the space for outdoor units is limited consider VRF units.

6. If outdoor sound level is required to be limited consider VRF units.

7. For two story buildings with flat roofs, consider rooftop units for second floor and splitsystems for first floor.


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Maroko & Shwe, Inc., 1106-B W. Magnolia Blvd., Burbank , CA 91506Tel: (818)-840-0280 Fax: (818) 840-0284 e-mail: [email protected]

8. Extra care should be taken about the location of outdoor units.They could bethe source of outdoor noise intrusion if they are located near windows, louvers orother openings into the building. If they are accessible or even visible from outside,they are open to the risk of theft or vandalism. The accessibility of the units to thestudents is a risk to physical harm.

Figure 1: Decision tree based on the recommendations (Please review the entire repand other project specific information before making a decision on a project)


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Individual system description and evaluations

Rooftop Gas Electric Units

Rooftop packaged air conditioning units with gas heating are currently the most preferredsystems for new construction. The energy efficiency of these units is the highest among unitary

packaged systems. The sound levels are well proven to be below 45 dBA with proper designand installation. The reliability is also well proven. Maintenance of these units is the mostconvenient as the entire unit is readily accessible on the roof.

However, for existing facilities, the following issues exist for the rooftop units:

1. The existing roof support structure is not capable of supporting the added weight of theunit and vibration isolator curbs and the structure is required to be modified.

2. The existing roof framing cannot accommodate the required duct sizes. The roof framingis required to be modified.

3. For buildings with sloped roofs, the units installed on the roof are unsightly and also not

very safe for the service personnel as a level service platform is not typically provided.Please refer to Figures 1 and 5.

4. Air distribution ductwork is required inside the room for proper air distribution and soundattenuation. Modification of the existing ceiling is required in most cases. Sometimes theupgrade of existing lighting is required. Relocation of existing items such as firesprinklers, fire alarms, technology conduits, etc. could be inconvenient and costly. If thereis limited or no space above the ceiling, the ductwork has to be installed exposed insidethe room.

5. Duct shafts through the second floor are required for the first floor of two story buildings.

6. The existing roofs in wood frame buildings might not offer sufficient sound attenuation.

Still, the rooftop units are viable options for buildings with flat roofs and parapets. This office isusing these units for the second floors of the two story classroom buildings of the LAUSD VeniceHigh School. This school has no space above the ceiling on the second floor. We terminatedboth supply and return air ducts at the roof penetration. We developed a special diffuser so thatair may be distributed effectively throughout the entire room from one diffuser installed at theroof penetration. Drawings and photos of these arrangements follow.

Figure 2: A 4 Ton Rooftop Gas Electric with springisolator curb and down shot duct configuration.LAUSD Venice High School


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Figure 3: Partial roof plan of two story classroom building with rooftop units for secondfloor and split system heat pumps units for first floor. Second floor will have diffusersand registers at duct penetrations only and no ductwork inside room. From LAUSDVenice High School


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Figure 4: Partial floor plan of second story classroom with diffusers and registers atduct penetration and no ductwork inside room at LAUSD Venice High School


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Figure 5: Section of second story classroom with registers at duct penetration and noductwork inside room at LAUSD Venice High School


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A (4) Nominal Ton capacity Rooftop gas electric unit have the following characteristics:

Make & Model: CARRIER 48 LC A05

Efficiency: 17.5 SEER [Seasonal Energy Efficiency Ratio (BTU of cooling/Watt of electricity)]

13.1 EER [Energy Efficiency Ratio (BTU/Watt) at peak load]

Outdoor sound level: 78 dBA

Unit weight: 1,160 LBS including isolator curb

Equipment Cost: $ 5,475 Means

$ 8,000 as quoted by Carrier with isolator curb

Total Mechanical Installed Cost: $ 14,280 Means 2012

Total Installed Cost including Architectural, Structural and Electrical: $ 24,100 from the scheduleof values of LAUSD Venice High School 2011 with no ceiling modifications. $ 32,000 expectedwith ceiling and lighting modifications.

The duration of the installation of one new rooftop unit for a classroom is 5 working days. TheMeans labor cost for installation is $ 5,742.

Manufacturers included in the current LAUSD Guide Specifications: Carrier, Lennox, Trane &York.

Please refer to page 7 of the attached HVAC Systems Acoustical, Cost and Energy Study forfurther information on the basic system description and recommended method of installation forbest energy and acoustical results.

Figure 6: Single story classroom building with sloped roof and rooftop gas electric uniton roof with horizontal duct configuration


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Rooftop Heat Pumps

Rooftop heat pumps are similar to rooftop gas electric units in all aspects except heating. Gaselectric units use natural gas in a furnace to heat. Heat pumps use the refrigeration compressorto heat by reversing the refrigerant flow between indoor and outdoor coils with a specialreversing valve. Heat pumps have been well proven to provide reliable heating for schools in

Los Angeles weather which is relatively mild. Rooftop heat pumps are installed where there is noexisting gas supply. The cost is slightly lower. The operating cost is slightly lower than a gaselectric unit of the same capacity operating under the similar conditions. This is due to lower airmoving energy from lower internal resistance to air flow as there is no furnace inside a heatpump. However, morning warm up time is longer and supplemental electric heaters are requiredwhere the outdoor design heating temperatures are lower.

A (4) Nominal Ton capacity Rooftop heat pump unit have the following characteristics:

Make & Model: CARRIER 50HCQA05


12.8 EER [Energy Efficiency Ratio (BTU/Watt) at peak load]Outdoor sound level: 78 dBA

Unit weight: 840 LBS including isolator curb


$ 8,000 as quoted by Carrier with isolator curb

Total Mechanical Installed Cost: $ 14,280 Means

Total Installed Cost including Architectural, Structural and Electrical: $ 24,100 from the scheduleof values of LAUSD Venice High School. There is very little cost difference between rooftop heatpumps and gas electric units if there is an existing gas supply.

The duration of the installation of one new rooftop unit with ductwork for a classroom is 5working days excluding architectural and structural modifications. The Means labor cost forinstallation is $ 5,742.


Split gas electric systems

Split gas electric systems are comprised of an outdoor condensing unit and an indoor sectionwhich has a cooling coil installed on a gas forced air furnace. The overall configuration is similarto a split system heat pump. We are dismissing this system altogether for the following reasons:

1. The internal resistance to air flow of the furnace makes the system less efficient.

2. The higher air flow resistance also makes the unit sound level higher.

3. The furnace also contributes to the indoor sound level.


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4. A gas supply is required inside the classroom.

5. Combustion air intakes and combustion product flues are required to be installed.

Split system heat pumps

Split system heat pumps are currently the second most preferred systems for new construction.The energy efficiency of these units is only slightly less than the rooftop unit systems but theoperating cost is the lowest. This is due to lower air moving energy from lower internalresistance to air flow as there is no furnace inside a heat pump. It has been well proven in newconstruction that the indoor air distribution is very effective with split system heat pumps withductwork above ceiling. The sound levels also are measured to be better than rooftop units ofsimilar capacity with an average of about 40 dBA with proper design and installation withductwork above ceiling. The reliability is also well proven. However, maintenance is the not asconvenient as the indoor fan coil unit is above the ceiling and has to be serviced after hours.

The existing roof support structure is usually capable of supporting the added weight of the

outdoor section of the split system heat pump unit as it is significantly lighter than the packagedgas electric unit. The rooftop unit weighs 1,160 LBS and the split system heat pump only weighs350 LBS.

For buildings with sloped roofs, the units installed on the roof are still unsightly and not very safefor the service personnel.

Air distribution ductwork is required inside the room for proper air distribution and also soundattenuation. Modification of the existing ceiling is required in most cases.

Ductless fan coil units are available but they have been studied in detail through pilotinstallations in 2005 in the reference report Duct Free Split System Heat Pumps as Alternativefor Wall Mounted Heat Pumps in existing classrooms, March 21, 2005 and rejected for

insufficient air filtration and outdoor air capacity characteristics.

To avoid the inconvenience and cost of ceiling modification, some manufacturers havedeveloped a floor mounted cabinet to contain the indoor fan coil unit to attenuate the sound andprotect the unit from being vandalized. These enclosures have been installed at a number ofLAUSD schools and a large number of California schools. The measured sound levels withthese enclosures are less than 50 dBA with varying results from below 40 dBA with Mitsubishiunits to about 48 dBA with Carrier furnaces. Furnaces have higher sound levels due to thehigher internal resistance to air flow by the furnace in addition to the cooling coil. We haveproposed improvements for these enclosures to reduce the sound levels with conventional splitsystem fan coil units. We also lowered the energy use further by not having ductwork above the

ceiling and installing the indoor fan coils in a floor mounted acoustical enclosure. We expectthese improvements will be factory tested in the near future. Please refer to figures 6, 7 and 8.

The split system heat pump units are the most viable options for the first floor of a two storybuilding with flat roofs and parapets. This office is using these units for the first floors of the twostory classroom buildings of the LAUSD Venice High School. This school has no space above


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the ceiling. We are installing the indoor fan coils inside the cabinets mentioned above. We areproposing special registers so that air may be distributed effectively throughout the entire roomfrom the cabinet installed at one corner of the room.

The split system heat pump units are also the most viable options for the single story buildingswith sloped roofs. The outdoor units can be installed on grade in a group at one end of the

building inside a block wall or chain link enclosure. The refrigerant lines can be run from theoutdoor units to the indoor fan coils up to about 150 feet.

The outdoor sections of the split system heat pumps are also available in a rectangular suitcaseshape with horizontal air flow. These suitcase shaped units can be stacked two deep one on topof the other on a frame to reduce the enclosure size. Refer to figure 9.

Drawings and photos of these arrangements follow.

Figure 7: Square split system heat pump unit outdoor section on roof

Figure 8: Suitcase type split system heat pump unit outdoor section


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Figure 9: Stacked suitcase type split system heat pump unit outdoor sections

Figure 10: Fan coil uni t enclosure


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Figure 11: Fan coi l unit enclosure wi th a 4 Ton fan coi l inside

Figure 12: LG Single Zone Split System Heat Pump and Fan coi l uni t


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Figure 13: Partial floor plan of first floor classroom with fan coil unit inside cabinet andno ductwork, inside room at LAUSD Venice High School


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Figure 14: Partial floor plan of first floor classroom with fan coil unit inside cabinet andsupply air ductwork ins ide room at LAUSD Venice High School


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Figure 15: Section of first floor c lassroom wi th fan coil unit inside cabinet and supply airductwork inside room at LAUSD Venice High School


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A 4 Nominal Ton capacity split system heat pump have the following characteristics:

Make and Model: Carrier 25HBC348 with FV4CNB006 (Square configuration)




Unit weight: Outdoor heat pump 266 LBS including isolator base rail

Indoor fan coil 172 LBS

Equipment Cost: $ 3,150 Means 2012

$ 4,059 as quoted by Carrier with isolator rail

Alternate Make and Model: Carrier 38QRR048 with FV4CNB006 (Suitcase configuration)

Efficiency: 15 SEER [Seasonal Energy Efficiency Ratio (BTU of cooling/Watt of electricity)]


Outdoor sound level: 71dBA

Unit weight: Outdoor heat pump 330 LBS including isolator base rail



$ 4,059 as quoted by Carrier with isolator rail

Total Mechanical Installed Cost: $ 10,170 Means 2012Total Installed Cost including Architectural, Structural and Electrical: $ 14,100 from the historicalcost of 2009 to 2011 for northern and southern California as provided by the Benoist Company

Cost of Acoustical Cabinet Enclosure: $ 5,000

Total Installed Cost including Architectural, Structural and Electrical with acoustical enclosure:$20,000 from the historical cost of 2009 to 2011 for northern and southern California as providedby the Benoist Company

The duration of the installation of one new split system heat pump unit in a sound enclosureinside a classroom is 3 working days. The Means labor cost for installation is $ 5,650.


Please refer to page 14 of the attached HVAC Systems Acoustical, Cost and Energy Study forfurther information on the basic system description and recommended method of installation forbest energy and acoustical results.


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Variable refrigerant flow systems

Variable refrigerant flow systems are similar to split system heat pumps. The only difference isone outdoor section can serve multiple indoor fan coil units. Ductless fan coil units are widelyused with this type of system but the ductless fan coils have been studied in detail through pilotinstallations in 2005 in the reference report Duct Free Split System Heat Pumps as Alternative

for Wall Mounted Heat Pumps in existing classrooms, March 21, 2005 and rejected forinsufficient air filtration and outdoor air capacity characteristics. We are recommending thissystem with conventional fan coil units only. We can install the fan coil unit inside a floormounted cabinet or enclosure in a similar fashion to the split system heat pump fan coils.

The energy efficiency of the variable refrigerant systems is slightly lower than conventional splitsystem heat pumps when the energy calculations are done with EnergyPro in compliance withCalifornia Energy Commission requirements. However, the manufacturers claim that the partload efficiency of the VRF units is significantly higher than the conventional heat pumps. We ranTitle-24 non-compliance calculations with EnergyPro with the equipment performance librariessupplied by LG and compared them with similar equipment performance libraries supplied by

Carrier for conventional split system heat pumps. The results are tabulated and presented as acomparative statement. The VRF units are found to be more efficient.

The outdoor sections of the variable refrigerant systems are more than 5-0 high for mostmanufacturers. They are not suitable for rooftop installation for single story buildings with slopedroofs. Please refer to Figure-16.

One variable refrigerant flow unit that can serve five classrooms can be installed in the spacerequired for three non-stacking, conventional split system heat pump outdoor sections. Thespace savings are however not very significant. A drawing comparing the two arrangements isprovided as Figures-17 and 18.

The difficulty level of installation and service is also expected to be higher than conventional

rooftop and split system units.The main advantage of these units is outdoor sound level which averages about 61dBA. Theconventional split system heat pumps average about 74 dBA.

A (12) Nominal Ton capacity variable refrigerant flow heat pump have the followingcharacteristics:

Make and Model: LG ARUN 144 BT3

Efficiency: N/A SEER [Seasonal Energy Efficiency Ratio (BTU of cooling/Watt of electricity)]


17.5 IEER [Integrated Energy Efficiency Ratio (BTU/Watt) at part load]


Unit weight: Outdoor heat pump 617 LBS for a 12 Ton unit


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Equipment Cost: Means cost not available

$ 15,000 as quoted for a 12 Ton unit for three classrooms with fan coils included

Total Mechanical Installed Cost: Means cost not available

Total Installed Cost for one classroomincluding Architectural, Structural and Electrical: $30,000 from the average schedule of values of the San Diego Unified School.

The duration of the installation of one new 12 Ton unit for 3 classrooms is 5 working days withsound enclosures.

Manufacturers included in the current LAUSD Guide Specifications: None

Recommended manufacturers: Daiken, LG & Mitsubishi

Figure 16: 12 Ton Outdoor Sections of Mitsubishi and LG VRF Units


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Figure 17: (4) 12 Ton Outdoor Sections of Mitsubishi VRF Units in enclosure


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Figure 18: (12) 4 Ton Conventional Split System Heat Pump Units Stacked inside anenclosure


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Wall mounted heat pumps

The new generation wall mounted heat pumps are significantly improved in energy efficiencyand acoustical performance. They could be the most cost effective for replacement of anexisting wall mount unit and are still a viable option where aesthetics are acceptable. Thisreasoning is true only if the physical size and configuration of the unit has not changed to require

structural and architectural modifications.

The energy efficiency of the new wall mounted heat pump systems is slightly lower thanconventional split system heat pumps when the energy calculations are done with EnergyPro incompliance with California Energy Commission requirements. However, the manufacturers claimthat the part load efficiency of the new wall mounted heat pump units is significantly higher thanthe conventional heat pumps. We cannot substantiate this claim until the simulation softwareEnergyPro is updated.

Figure 19: Wall mounted heatpump unit at Century Park Elementary School


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Figure 20: Floor plan of Wall Mounted Heat Pump Unit with no ductwork


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Figure 21: Section of Wall Mounted Heat Pump Unit with no ductwork


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Figure 22::Floor plan of Wall Mounted Heat Pump Unit with supply air ductwork


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Figure 23: Section of Wall Mounted Heat Pump Unit with no ductwork


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A (4) Nominal Ton capacity wall mounted heat pump unit have the following characteristics:

Make & Model: Bard T48S1 (Future 2 compressor model)

Efficiency: (Not published) SEER [Seasonal Energy Efficiency Ratio (BTU of cooling/Watt ofelectricity)]

11 EER [Energy Efficiency Ratio (BTU/Watt) at peak load]15.8 EER with one compressor working at part load


Unit weight: 605 LBS shipping weight

Equipment Cost: Means cost not available

$ 11,224 as quoted by Bard for a current unit with adaptor, isolation curbs,acoustical supply plenum and other required accessories

Total Mechanical Installed Cost: Means cost not available

$ 14,000 for replacement only with no structural modifications based onaverage historical data of last five years

Total Installed Cost including Architectural, Structural and Electrical: $ 16,000 for replacementonly with no structural modifications based on average historical data of last five years

The duration of the installation of one replacement wall mounted unit for a classroom is 1working day. This is true only if the physical size and configuration of the unit has not changed torequire structural and architectural modifications.

The Means labor cost for installation is not available.

Manufacturers included in the current LAUSD Guide Specifications: Bard, Marvair

Typical wall mount unit installations as recommended by the manufacturer follows. The typicalLAUSD installations are either free flow or ducted supply only.


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Figure 24: Typical wall mount unit installations as recommended by manufacturer


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Indoor cabinet type heat pumps

This office installed Airedale Cabinet Type Heat Pumps for Emery Park Elementary School inthe Alhambra Unified School District in 2010. LAUSD also have these units installed at Aragonand Washington Prep Schools. Client satisfaction, acoustical performance and reliability forthese units are not as high as the rooftop or split system units. Please refer to figure 25.

This unit has the following disadvantages.

1. It is the necessity to install the unit against an exterior wall with sizeable wall louversthrough the wall.

2. The footprint or floor area required is larger than the fan coil unit cabinet.

3. The unit sound level is closer to 50 dBA than 45.

4. The unit is heavy and is relatively difficult to move into the classroom. The unit also doesnot fit through an existing door.

5. The difficulty level of installation and service is also expected to be higher than

conventional rooftop and split system units.

Figure 25: Indoor cabinet type heat pump unit currently installed at LAUSD WashingtonPrep School and Aragon School


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Figure 26: Floor Plan of Indoor Cabinet Type Heat Pump with supply air ductwork.Alhambra Unified School District, Emery Park Elementary School


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Figure 27: Section of Indoor Cabinet Type Heat Pump with supply air ductwork. AlhambraUnified School Distr ict, Emery Park Elementary School


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A (4) Nominal Ton capacity Airedale Indoor Cabinet Type Heat Pump unit have the followingcharacteristics:

Make & Model: Airedale CHH4



Unit weight: 735 LBS including isolator curb

Equipment Cost: $ 13,000 from the schedule of values of AUSD Emery Park ElementarySchool 2009.

Total Installed Cost including Architectural, Structural and Electrical: $ 30,000 from the scheduleof values of AUSD Emery Park Elementary School 2009.

The duration of the installation of one replacement indoor cabinet type unit for a classroom is 2working days. This is true only if the physical size and configuration of the unit has not changed

to require structural and architectural modifications. The Means labor cost for installation is notavailable.

Manufacturers included in the current LAUSD Guide Specifications: Bard, Marvair

4 pipe Hydronic fan coils

Hydronic fan coils are a viable option only if there is an existing chilled and hot water supply.Then a 4 pipe fan coil unit can be installed inside a cabinet in a similar fashion as a DX fan coilinside the room.

New chilled and hot water plants are not recommended. They have the following disadvantages:

1. They take a very significant amount of space. Please refer to the figures 28, 29 and 30..

2. The energy efficiency is also low. The chillers are only 10+ EER while unitary equipmentis 12+.

3. The initial cost is high.

4. They are difficult to install.

5. They are difficult to operate.

6. They are very noisy. The sound level of the air cooled chiller can be as high as 110 dBA.

Please refer to page 21 of the attached HVAC Systems Acoustical, Cost and Energy Study for

further information on the basic system description and recommended method of installation forbest energy and acoustical results.


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A 60 Nominal Ton capacity air cooled chiller for 12 classrooms have the followingcharacteristics:

Make & Model: York

Efficiency: SEER is not applicable to 3 equipment


Unit weight: 4142 LBS


$ 8,000 as quoted by Carrier

Total Mechanical Installed Cost: $ 248,400 Means

A 0.75 MBTUH Capacity outdoor boiler for 12 classrooms have the following characteristics:

Make & Model: Patterson Kelly

Efficiency: 80 % (87 % condensing is not applicable with 140F return)


Unit weight: 455 LBS


Total Mechanical Installed Cost: $ 16,600 (Means)

Total Central Plant Mechanical System Installed Cost: $ 281,600 (Means 2012)

Total Installed Cost including Architectural, Structural and Electrical: $ 380,160 (Means 2012)

That is equivalent to $ 32,000 per classroom.

The duration of the installation of one central plant for 12 classrooms is 30 working days. TheMeans labor cost for installation is $ 113,760 or $ 9.480 per classroom.

Manufacturers included in the current LAUSD Guide Specifications: Carrier, McQuay, Trane &York.


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Figure 28: 80 Ton Air Cooled Chiller

Figure 29: Outdoor Boilers and pumps


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Figure 30: Plan of enclosures for 60 Ton Air Cooled Chiller and 1 MBTUH with requiredaccessories


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Chilled Beams

There are two types of chilled beams, active and passive. This discussion will be limited to activechilled beams. An active chilled beam is an induction type heating and cooling device whichcauses room air motion through induction of high velocity air jets. The simplest explanation is itis like a diffuser with integral heating and cooling coils. Pretreated (preheated or precooled and

dehumidified filtered air) from a dedicated outdoor air system is ducted to the chilled beams. Theair then goes through distribution nozzles inside the device and increases in velocity. This highvelocity air stream induces room air to flow across the heating and cooling coils inside the deviceand mix with it. The resultant mixed cooled or heated air is then distributed into the space.Please refer to Figures 31through 35.

The two major advantages of this system is less air moving energy and less space for ductwork.This system is also very quiet. It is suitable for existing buildings with limited space above theceiling. They are also preferred for laboratories and similar applications where 100% outdoor airwith no return air is required.

There are also major disadvantages. A central heating and cooling plant for chilled and hot

water is required. Air handling units for dedicated outdoor air is also required. The chilled watertemperature to the devices has to be controlled above room dew point to prevent condensation.The engineering principles behind the device are somewhat esoteric.

We do not recommend this system for schools except for historical buildings with abundantbudgets.

A chilled beam system with a 60 Nominal Ton capacity air cooled chiller and a 0.75 MBTUHCapacity outdoor boiler for a 12 classroom building have the following characteristics:

The efficiencies of the chiller and boiler will be similar to the central plant for the fan coil unitsystem.

Total Central Plant Mechanical System Installed Cost: $ 281,600 (Means 2012)Total additional cost for dedicated outdoor air unit, chilled beams, heat exchanger for thesecondary chilled water to the chilled beams, piping, pumps ductwork and controls: $ 248,000

Total Installed Cost including Architectural, Structural and Electrical: $ 628,560 (Means 2012)

That is equivalent to $ 52,000 per classroom.

The duration of the installation of one central plant for 12 classrooms is 30 working days. TheMeans labor cost for installation is $ 113,760 or $ 9.480 per classroom.

Manufacturers included in the current LAUSD Guide Specifications: None


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Figure 31: Active Chilled Beam

Figure 32: Act ive chilled beam installation

Figure 33: Act ive chilled beam installation and air flow schematic diagram


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Figure 34: Floor Plan of Classroom with Chilled Beams, Pasadena Unified School Distric t,Blair High School


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Figure 35: Floor Plan of Classroom with Chilled Beams, Pasadena Unified SchoolDistrict, Blair High School


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LG Installation @ Grant High School

Figure 36: LG Single Zone Split System Heat Pump and Fan coi l uni t @ Grant HighSchool

The LG unit installed at Grant High School is a single zone split system Variable RefrigerantFlow heat pump with the following characteristics.

Make and Model: LG ARUN047GS2 heat pump with ARNU483NKA2 indoor fan coil unit



Outdoor sound level: 51 / 53 dBA (Cooling / Heating)

Indoor Fan Coil Unit Sound Level: 49 / 47 / 41 dBA (High / Medium / Low Speeds)

Unit weight: Outdoor heat pump 234 LBS net unit weight


Equipment Cost: $ 3,150 Means 2012

$ 5,455 as quoted by LG

The indoor unit will need to be operated at medium speed to satisfy the capacity requirements.We recommend that this unit be installed in the same acoustical cabinet that was recommendedfor the conventional fan coil units at Venice High School in Figure 13 to maintain the classroom


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sound levels below 45 dBA, prevent students from accessing the unit and for better anchorageand aesthetics.

Extra care should be taken about the location of outdoor uni ts.They could be the sourceof outdoor noise intrusion if they are located near windows, louvers or other openings into thebuilding as installed. The LG outdoor unit is very quiet with only 51 dBA during cooling but the

existing glazing could be single glazed and might not have sufficient attenuation value.Replacement of adjacent glazing might be necessary. The wall mounted units have asignificantly higher outdoor sound level of 64 dBA for the future units that are not in the marketas yet. The current units are about 66 dBA outdoor sound level.

If the outdoor units are accessible or even visible from outside the school compound, they areopen to the risk of theft or vandalism. The accessibility of the units to the students is a risk tophysical harm. A protective enclosure is necessary. The wall mounted units impose the samerisk.

The condensate drain should be discharged to a drywell located far enough away from the

structural foundations or a planter.

This unit is a residential type unit and is limited to 230 V 1 electrical power supply only. 480V 3 units are preferred for classroom applications. If the existing wall mounted unit is wiredfor 3 power, an 8 Ton unit could be installed to serve two fan coils in two classrooms. Theservice can remain but the wire and breaker sizes will need to be increased. The 8 Ton unitshave the outdoor sound level of 58 dBA and are still quieter than the wall mounted units.

The construction of this unit is also not as robust and sturdy as the conventional US madeunits. We are of the opinion that this unit might not be as durable also due to the presence ofplastic components. However, the plastic components are just in the casing and themanufacturers offered to provide custom metal components.

This unit has a higher SEER than the conventional Carrier split system heat pump unit; 15.2against 14.8 but a lower EER; 9.5 against 12.5. Calculations with the current version ofEnergyPro will not provide a significantly better result than the Carrier unit. We calculated theannual energy cost to be $ 1.65 per square foot per year for this unit in the valley. The costwith the Carrier unit is $ 1.71.

We went to the jobsite on November 19thand took sound level and temperature distributionmeasurements. We measured at 5 from the front of the unit, center of room and 5 out fromeach corner. The results are found to be favorable at 45 dBA and 72 F at all locations.

Total Installed Cost including Architectural, Structural and Electrical is $ 14,100 from thehistorical cost of 2009 to 2011 for northern and southern California as provided by the BenoistCompany. LG concurs with the number.

Cost of Acoustical Cabinet Enclosure: $ 5,000


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Total Installed Cost including Architectural, Structural and Electrical with acoustical enclosure is$20,000 from the historical cost of 2009 to 2011 for northern and southern California as providedby the Benoist Company. LG concurs with the number.

The duration of the installation of one new split system heat pump unit in a sound enclosureinside a classroom is 3 working days. The Means labor cost for installation is $ 5,650.

Manufacturers included in the current LAUSD Guide Specifications: None at present.

Manufacturers of similar equipment: Daiken, Mitsubishi

hvac_units_for_the_replacement_of_wall_hung_units__11_15_2012.pdf

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