Efficiency Vermont is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. Joe Cefaly Mitsubishi Electric
Learning Objectives Basics of heat pump technology How VRF systems are different than older technologies Advantages of these systems for average buildings and high performers as well How to properly apply VRF systems for cold climates
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Basics of Heat Pump Technology
Basic Refrigeration Cycle RED = Higher Temp/Pressure BLUE = Lower Temp/Pressure
Basic Refrigeration Cycle Evaporator High-Pressure Vapor High-Pressure Liquid Condenser Low-Pressure Liquid Low-Pressure Vapor
Basic Refrigeration Cycle RED = Higher Temp/Pressure Subcooled Liquid Condensing Pressure Expansion Cycle Liquid Liquid and Gas Gas Evaporating BLUE = Lower Temp/Pressure Superheated Gas Enthalpy
Refrigeration Components
Hermetic (refrigerant cooled) Typically constant speed (on/off) Improved technology provides variable speed/variable flow Smaller sizes Multiple scrolls used for larger capacities Scroll Compressor
Scroll Compressor Intake Compression Fixed Scroll Orbiting Scroll Assembled Scrolls Discharge
Compressor Evaporator High-Pressure Vapor High-Pressure Liquid Condenser Low-Pressure Liquid Low-Pressure Vapor
Condenser Air or Water Refrigerant changes from gas to liquid
Condenser Evaporator High-Pressure Vapor High-Pressure Liquid Condenser Low-Pressure Liquid Low-Pressure Vapor
Thermal Expansion Valve (TXV) Metering Device used in traditional DX systems Controls superheat at outlet of coil Capillary Tubing External Equalizer Line
TXV Evaporator High-Pressure Vapor High-Pressure Liquid Condenser Low-Pressure Liquid Low-Pressure Vapor
Evaporator Heat and moisture is removed from the air stream Refrigerant evaporates Suction Header Fins Feeder Tubes Refrigerant Distributor Evaporator Tubes
Evaporator Coils
Evaporator Evaporator High-Pressure Vapor High-Pressure Liquid Condenser Low-Pressure Liquid Low-Pressure Vapor
Reversing Valve Used in Heat Pumps Allows change in refrigerant flow direction to switch between heating or cooling mode
How VRF Systems are Different than Older Technologies
What is VRF? Variable Refrigerant Flow
Brief Description VRF Moving refrigerant rather than air for zoning Inverter-driven compressor performs at the minimum energy level necessary to provide comfort in each zone (down to 6% capacity) Each variable capacity indoor unit operates independently from the other indoor units for individual zone comfort control Supply air conditioning and heating only to rooms that require it Uses natural building diversity to reduce initial equipment investment
Worldwide Usage Window Japan 90% 7.2M Systems Unitary Chillers Moveble Ductless China 86% 16.7M Systems USA 3% 0.2M Systems Europe 81% 7.6M Systems Ductless is a small percent of the U.S. HVAC market but current building and energy usage trends indicate a large growth opportunity
Inverter-Driven Compressors What is an Inverter? A variable speed drive that changes the voltage and frequency being fed to the motor Think of the inverter as a throttle control Changes electrical frequency from 60 Hz to a varying range of 15 Hz to 125 Hz Frequency is affected by: Number of indoor units operating Outdoor unit model Outdoor unit target temps/pressures Greatly reduces energy usage
Inverter-Driven Compressors Room Temperature Set Temp. Very slow! Conventional ON/OFF Systems Too warm 90 F Uncomfortable! 79 F 77 F OFF Too cool 75 F 60Hz Inefficient! ON High starting current = Energy loss 0Hz
Inverter-Driven Compressors Room Temperature Inverter Compressor Advantage 90 F Set Temp. Very fast! Room temperature is steady High rotation speed up to 100 125Hz generates accelerated performance! Adjust rotation speed precisely to keep steady room temperature Comfortable! 75 F 150Hz 60Hz 30Hz Very efficient! ON Compressor starting current at low level 0Hz Keep rotation speed low after temperature is stabilized
VRF System Types VRF Heat Recovery Technology (Air-Source) Simultaneous Heating and Cooling Simultaneous Heating and Cooling
VRF System Types VRF Heat Recovery Technology (Water-Source) Simultaneous Heating and Cooling Heat is recovered between the condensing units within the water loop Heat is recovered between the indoor units within the refrigerant loop (To cooling tower/boiler or geothermal field)
VRF System Types VRF Heat Pump Technology (Air-Source) HEATING COOLING
VRF System Types VRF Heat Pump Technology (Water-Source) PQHY Unit A COOLING Heat is recovered between the condensing units within the water loop PQHY Unit B HEATING Water Circuit (To cooling tower/boiler or geothermal field) Refrigerant Circuit
Typical Heat Recovery System: Heat Recovery Systems with a connected capacity of 150%. Available up to 24 tons. Outdoor or Water Source Unit + BC Controller + Indoor Units + Control System = Simultaneous Cooling, Heating
Typical Heat Pump System: Heat Pump Systems with a connected capacity of 130%. Available up to 30 tons. Outdoor or Water Source Unit + Headers and/or Branch Joints + Indoor Units Control + System = Heat Pump
Product Lineup: Cassette Style Indoor Units Ducted Style Exposed Style
Product Lineup: Energy Recovery Ventilators Cross-flow energy exchange core ~ 70% recovery of sensible and latent energy Integrates with control system
Product Lineup: Controls System Easy to install and operate 2-wire direct digital control system 16ga stranded and shielded, non-polar Daisy-chain connection Customizable control scheme with web access Individual room controls Color touch screen centralized control Integration into building management system via BACnet and Lonworks Third-party equipment control Tenant billing capability
Advantages of these Systems for Average Buildings and High Performers as well
Zoned Comfort No more hot spot cold spot issues Individual control means individual comfort Quiet operation
Refrigerant Piping Flexibility PIPING LENGTH Water Simultaneous Water Heat Pump Air Cooled Single Phase Total Piping Length 2460 ft. 1650 ft. 3280 ft. 393 ft. PIPING HEIGHT Air Cooled Series Water Series S- Series Outdoor Unit HIGHER than Indoor Unit 164 ft.* 98 ft. Outdoor Unit LOWER than Indoor Unit 131 ft. 65 ft. Indoor Unit to Any BC Controller 49 ft. n/a n/a *Elevation differential up to 295 available in 2009. Additional limitations may apply
What Does QUIET Sound Like? Mitsubishi Indoor Unit As low as 19 db(a) Mitsubishi Ducted Unit How QUIET is VRF? As low as How LOUD As low is as a As traditional high as As low as HVAC unit? 23 db(a) Mitsubishi Residential Outdoor Unit 46 db(a) 57 db(a) 61 db(a) Mitsubishi Commercial Outdoor Unit 25 db(a) Recording Studio 33 db(a) Library 40 db(a) Quiet Home 50 db(a) Refrigerator 60 db(a) Conversation 70 db(a) Busy Traffic 78 db(a) Vacuum 90 db(a) Motorcycle 100 db(a) Hand Drill 50-60 db(a) 65-75 db(a) 75-85 db(a) PTAC Unit Residential 3-ton HVAC Unit Air-cooled Chiller
Energy Savings Inverter-driven compressors No waste heat with simultaneous heating and cooling Up to 130-150% indoor unit connected capacity Meets requirements for LEED points
Full Load vs Partload Efficiency 100% EER Power Consumption 0% 50% Unitary VRF 0% 30% 50% 70% 100% Equipment Loading
Space Savings Space Required to Deliver 20 tons of Cooling VRF 20 tons Ducted 20 tons 30 Round Supply Duct 1 1 /8 Liquid 1 1 /8 Gas Chilled Water 20 tons Ducted 20 tons 40 x 20 Supply Duct 3 CHW supply 3 CHW return
Ease of Installation Less intrusive to existing architecture Modular condensing unit design Smaller indoor unit electrical distribution Indoor unit flexibility and small size to meet the needs of any space
VRF Equipment Weight Savings Average equipment weight per ton for VRF is 70 lbs per ton (outdoor unit only) Average equipment weight per ton for water-cooled chiller is 101 lbs./ton 31% reduction in equipment weight 44
Weight Reduction = Structural Reduction 45
46 VRF Frees Up Building Space
Reduced Mechanical Space Traditional systems require space for pumps, boilers, chillers, ducts, piping, heat exchangers VRF offers efficiency without requiring the space 47
Ease of transportation VRF Installation Flexibility Easy installation
Roof top VRF Economy of Scale
Smaller Footprint = More Green Space 50
Where to use VRF? Buildings where zoning is important Retrofits and renovations Sound-sensitive applications
Where to use VRF? LEED and energy-efficiency projects University of Washington: 25% Energy Savings Hotel Terra: LEED Silver Mercy Corps: LEED Platinum
Case Studies John Joseph Moakley United States Courthouse Boston, MA Replacement of fan-powered VAV system with VRF Phase I was 9th and 10th floor renovations 120 tons of CITY MULTI water-source VRF Phase II is an additional 100 tons Future plans to replace all fan-powered VAV
Case Studies T.C. Williams High School Minnie Howard Campus Alexandria, VA Replacement of chiller/boiler 4-pipe system Geothermal system with 60 wells 46 tons of CITY MULTI WR2 Building energy savings of $32,500 per year over the base case CHW/HW system
Superior High School Superior, Nebraska 72,000 SF School 36,000 SF Heated and Cooled using VRF 36,000 Heated using Boilers School was served by two existing gas boilers and was heating only. Replaced old boilers with VRF and new modulating boilers to function as back-up heat. VRF Provided Cooling and Reduced Energy Use by 25%
Burlingham Hall LEED Gold Electrical usage reduction of 33.5% vs. ASHRAE 90.1 Baseline Gas usage reduction of 67% vs. ASHRAE 90.1 Baseline Awarded 7 LEED points for EAc1 $34,400 annual utility savings
How to Properly Apply VRF Systems for Cold Climates
Air-Cooled Heat Pumps Extremely efficient, but what about heating in cold climates? Heating capacity rated at 47F db / 43F wb As outdoor temperature decreases, heating capacity decreases Up to 76% heating capacity at 5F wb Up to 68% heating capacity at -4F wb How do we overcome this heating capacity de-rate?
PROS: Option 1: Hyper-Heat Unit Excellent low temperature heating performance 100% heating capacity at 5F wb 87% heating capacity at -5F wb 75% heating capacity at -13F wb No auxiliary heat needed No need to oversize equipment CONS: Non-simultaneous system Requires changeover 208-230/3/60 only Higher cost of Hyper-Heat vs. Standard VRF Heat Pump
Option 1: Hyper-Heat Unit
Hyper-heating INVERTER Y-Series Outdoor Units Comfortable indoor air temperatures even at low outdoor ambient temperatures (P72 Model) Indoor unit Discharge Temperature PEFY-P24NMAU with 70 o F Entering Air Temp High speed fan setting (671 cfm) High Heat Setting Discharge Temp o F 120 115 110 105 100 95 90 85 80 112 111 109 109 107 108 107 103 104-13 -10-4 0 5 10 15 20 25 Outdoor Temperature o F
Hyper-heating INVERTER Y-Series Outdoor Units Component Diagram (Heating) Outdoor Unit Reversing Valve Indoor Unit SV9 TH7 SV2 A B Comp. TH4 Indoor Coil Outdoor Coil LEV4 H Accum. G LEV2a TH2 J HIC IDU LEV C TH3 F D E TH6 LEV1 High Pressure B - C Medium Pressure C - E/F Low Pressure G - H Injection Circuit E - A Superheated Vapor Liquid Saturated Liquid Saturated Liquid Subcooled Liquid Subcooled Liquid Superheated Vapor Liquid/Vapor mixture Liquid/Vapor Mix
Hyper-heating INVERTER Y-Series Outdoor Units Pressure-Enthalpy Cycle (Heating) Liquid is subcooled here before entering the outdoor coil IDU LEV C B F LEV1 E D The heat that is normally wasted in the flash process at the outdoor coil is picked up here in the HIC (heat interchanger). LEV2 I HIC J LEV4 A Standard System Flash injection enters compressor here to cool compressor G H Area of efficiency gained in the outdoor coil normally lost to flash gas
Option 2: Oversizing the System Size the system for the heating load at the heating design day (low outdoor temperature) Ex: Use a nominal 14-ton system for a 10-ton heating load at 5F Both outdoor units and indoor units must be oversized Won t over-cool because of inverter on compressor
Option 2: Oversizing the System PROS: Can utilize simultaneous heat recovery system (R2) No auxiliary heat needed CONS: Higher equipment cost / larger outdoor equipment Larger indoor units have more airflow Larger refrigerant piping / more refrigerant
Heating Comparisons PUHY/PURY Percent heating capacity @5F Current T/Y(S)HMU NEW T/Y(S)JMU Standard Setting NEW T/Y(S)JMU High Heat Setting Approx. Increase High Heat vs Current Units PUH/RY-P72 60% 60% 74.5% 24% PUH/RY-P96 60% 60% 74.5% 24% PUH/RY-P120 60% 60% 70% 31% PUH/RY-P144 60% 60% 66% 10% PUH/RY-P168 60% 60% 75.2% 25% PUH/RY-P192 60% 60% 75.2% 25% PUH/RY-P216 60% 60% 70% 24% PUH/RY-P240 60% 60% 70% 31% PUH/RY-P264 Y-Series only 60% 60% 66% Y-Series only 16% PUH/RY-P288 Y-Series only 60% 60% 66% Y-Series only 14% PUHY-P312 Y-Series only 60% Y-Series only 60% Y-Series only 70% Y-Series only 28/% PUHY-P336 Y-Series only 60% Y-Series only 60% Y-Series only 70% Y-Series only 27% PUHY-P360 Y-Series only 60% Y-Series only 60% Y-Series only 70% Y-Series only 31%
Option 3: Auxiliary Heat Inside Building Auxiliary control available with all indoor units by utilizing factory-provided contact Two methods for energizing contact: Based on drop in space temperature Based on outdoor temperature VRF is the first stage of heat, auxiliary source is the second stage of heat
Option 3: Auxiliary Heat Inside Building PROS: Can utilize simultaneous heat-recovery system Take advantage of existing heating system if available Provide 100% heating capacity (no de-rate) No need to oversize equipment Auxiliary heat is usually small with low run hours CONS: Higher system installed cost More complex installation for non-ducted indoor units
Option 4: Locate Outdoor Units Inside (Utilize a Penthouse) By placing the outdoor units inside a penthouse, they are sheltered from the elements Can duct condenser air discharge (0.24 ESP capability) Must have heat source inside penthouse Must have heat trace if penthouse is kept below 32F Must carefully size and control louvers/dampers to ensure proper airflow and pressurization (condensers move a lot of air)
Option 4: Locate Outdoor Units Inside (Utilize a Penthouse) PROS: Can utilize simultaneous heat-recovery system Easier maintenance inside conditioned penthouse No need to oversize equipment Effective in extremely cold climates Aesthetics CONS: Penthouse design can be complicated Additional cost of penthouse Still need auxiliary heat (inside penthouse vs. inside building) Auxiliary heat runs on outdoor air temperature, not indoor space temperature Space required for penthouse
Questions?