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VRF Equipment & Applications

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Presentation on theme: "VRF Equipment & Applications"— Presentation transcript:

1 VRF Equipment & Applications
Ruben Willmarth West Region Sales Manager Toshiba Carrier Ductless & VRF November 07, 2014 Billings, MT Joint Engineering Conference

2 Global Application Examples Benefits of VRF systems System Components
CONTENTS What is VRF Global Application Examples Benefits of VRF systems System Components Controls Basic Design Practices ASHRAE Std 15 & 34 I will begin this presentation by explaining the advantages of the 3 inverter compressor design and end with its easy installation and maintenance. There will be eight sections in total.

3 WHAT IS VRF “VRF” system is a short for Variable Refrigerant Flow system. Refrigerant flow is varied based on demand - System where multiple (up to 50 indoor units) can be connected to outdoor units. - Fan coils are controlled individually or by group controls. - Refrigerant flows to the unit that is calling for heating or cooling.

4 VRF Technology Overview
Two VRF System Types Heat Recovery Heat Pump Single Mode: Cooling or Heating Only Simultaneous Cooling & Heating

5 VRF Technology Overview
Primary Components of a Heat Pump System Outdoor Unit Controls Compressor Speed Maintains Operational Mode Indoor Unit Transfers Heating and Cooling to Space Allows for Optimal Zoning Controller Controls Space Temp and IDU Fan Remote or Central

6 Liquid line (fully liquid)
Typical VRF Heat Pump System Outdoor unit Compressor Liquid line (fully liquid) Indoor unit Refrigeration Pipe (Liquid, Gas) Each indoor unit can be controlled individually. On/Off setting , Set point, Air volume, louver position can be set individually. (Operation mode priority : Cooling or Heating, not simultaneously in heat pump model) Cooling : Expansion=Indoor unit Liquid line=Condensed liquid Heating : Expansion=Outdoor unit  Liquid line =Condensed liquid 

7 VRF Technology Overview
How does VRF work? Indoor Unit Transfers heating and cooling directly to the space Measures Return Air Temperature Pulse Motor Valve (PMV) adjusts to meet setpoint Filters and distributes the air Unit operates to match exact building load Flow Selector Receives superheated gas and subcooled liquid, adjusts flow direction to heat and cool Allows for indoor unit to be in either cooling or heating mode Unit operates to match exact building load Outdoor Unit Houses multiple inverter driven compressors Compressors change speed based on demand of indoor units, which varies the refrigerant flow Segmented ODU Coil for efficient heat transfer Unit operates to match exact building load Controller Allows for indoor unit control at zone level Takes user desired space setpoint, fan speed, mode Unit operates to match exact building load

8 Typical VRF Heat Recovery System 3 - Pipe
Simultaneous heating and cooling, uses cooling mode waste heat for heating Heat Recovery Box

9 Typical VRF Heat Recovery System
2 - Pipe

10 Varying Refrigerant Flow
How does the outdoor unit respond to the varying demands and vary the flow of refrigerant? The compressor(s) in the outdoor units are inverter driven which means that their speed can be varied by changing the frequency of the power supply to the compressor. As the compressor speed changes, so does the amount of refrigerant delivered by the compressor.

11 SYSTEM ADVANTAGES High Efficiency High Stable Operation High
Reliability High Efficiency High Reliability I would now like to tell you about the high reliability which is offered by the 3 inverter compressor system.

12 Use Wherever Part Load Exists
Application: In case of: Not all units are on. Example: office area is on, meeting room is off. OFF In case of: Orientation of building Example: East/West exposure Apartment, In case of: Decreased load. Example: office closed Office building

(In case of cooling) OFF OFF OFF OFF : Piping : 4-way cassette type : Hi-wall type : Outdoor units

14 ADVANTAGES OF VRF - Comfort - Design flexibility
- Energy savings (part load, heating) - Cost effective installation


Rotary compressor Scroll compressor We can also divide compressors into two main categories, rotary compressors and scroll compressors. The construction of these two types differs significantly in that the compression part of a rotary compressor is positioned at the bottom of the main unit, while that of a scroll compressor is located at the top of the main unit.

Twin rotary compressor Scroll compressor Out Out In In You may be wondering why there is such a difference in characteristics. I will briefly explain, starting with the twin rotary compressor. The twin rotary compressor is constructed so that the compression ratio inside the cylinder and the refrigerant cycle are always balanced. The compression ratio inside the cylinder and the refrigerant cycle are the same, and there is minimal excess compression or insufficient pressure inside the cylinder. This means that even when the compression ratio inside the refrigerant cycle changes, the compressor still runs with high efficiency across the entire range. In 17

Multiple types of Fan Coils and Sizes provides design flexibility for many different applications

19 ADVANTAGES OF VRF Modularity of equipment allows for Staging of installation, Redundancy in operation




23 Shengshi Qiantang Garden
1200 apartments in 7 buildings Recognized by China’s Ministry of Construction as being among the most cost-effective air conditioning systems available. Shengshi Qiantang Garden 3,840Tons

24 Jae Neung Education Building

25 Portal Commercial Development

26 Burt Hill Architects Office
Approx. 10,000 sq. ft 7 floor multi-tenant office building Burt Hill Architects Office 26

27 Installed in subway passages and administration offices
Contracts extending to other lines China Subway 19,200Tons 27

28 DESIGNING WITH VRF High Efficiency High Stable Operation High
Reliability High Efficiency High Reliability I would now like to tell you about the high reliability which is offered by the 3 inverter compressor system.

29 Designing for Energy efficiency
Perimeter/Core Pres. Office 12 kBTU VP Office 14 kBTU Foyer 2.5kBTU Women’s 2.0kBTU Men’s Coffee/Brk Office 101 6.0kBTU Office 102 Office 103 Office 104 3.0kBTU Office 105 Office 106 Office 107 Office 108 Office 109 Office 110 4.5kBTU 7.5kBTU Conf. 28.0kBTU Corr 6 13.5 kBTU 1 12 kBTU 7 Rejected Heat 5 2 28 kBTU 2.5 kBTU 12 kBTU Each unit individually – list model numbers next to example 3 4 20 kBTU 14 kBTU Example: 40oF Ambient

30 Ventilation Design Ventilation Strategies with VRF
Room graphic w/Air into Corner Delivering OSA directly to the space: Best when it is Neutral temperature & Humidity (DOAS) An ERV-only is OK in the West & South, if low fraction and high ceilings (mixing time) Mild Climates can bring in small fraction untreated Benefits are less ducting, more flexible application (close-up of a room in an office with an arrow showing air coming in at one end and leaving at the other. If time, include a grill & ductwork for Supply Air and Exhaust Air to go with.)

31 Ventilation Design Ventilation Strategies with VRF
Delivering OSA ducted to the Fan Coil: Pre-Filtered, tempered air is best. (DOAS) Allows selecting to meet Envelope load for max comfort Air inlet point is before the filter on some ductless, so Filter is a must! An ERV-only is Good in the West & South, but may need additional heat in the North DOAS system or ERV+FC is best for Cold Climates Mild Climates can bring in small fraction untreated (<30%) Benefits are better humidity control, no extra grills Show a Ducted Fan Coil with air entering through the back, a 4-way cassette with air entering at the corner, (maybe even the extended casement with the extra air inlets?), and a Ceiling suspended with air coming from behind?

32 Ventilation Design DOAS using an ERV
DOAS approach allows us to split the ventilation load away from the Mechanical system by tempering the air first. Can use an ERV only for most applications Can run OSA through a standard Fan Coil in Series for Neutral Air application, especially if not ducted to Fan Coils Can apply Supplemental Heat for Cold Climate applications for Neutral Air, or even higher By treating each separately, we can optimize for each, instead of a one-size fits all compromise. Add Graphic to show on Roof a DOAS w/ ducting down to conference room?, with each option, ie. DOAS, ERV, ERV+FC.(verify with Nick)

33 Heating Design Heating Design Strategies Heating with a VRF System:
-VRF is a Heat Pump, but…. But it is not your Grandpa’s Heat Pump! Capacity is better than traditional because of inverter compressors that can spin faster to compensate De-rate due to ambient temperature is less, but must still be accounted for. Auxiliary Heat to cover the <average Visual for a better heat Pump?? Make sure that it is clear how the system de-rates due to low ambient temperatures.

34 Heating Design Heating Design Strategies- Avg. vs. Design:
The Design Heating in Billings is -20F But the Average January Low is 16F Discuss the difference between the design and the average, ie the bell curve, or the scatter-plots for annual temperatures. Maybe some red arrows pointing to the 3 key points on the heating capacity curve, at typical temperatures. “Avg. winter low in Billings, MT is 16F”

35 Ventilation Design Heating Design Strategies
When to use Auxiliary Heat? Rule of Thumb is start considering it at 15F design temp. Simple Answer is when heating Design Day exceeds capacity ERV & DOAS can provide significant contributions. “Avg. winter low in Seattle, WA is 36F” “Avg. winter low in Billings, MT is 16F” While it is necessary to design for the worst case load, it’s important to understand what the normal load on the system is. You can see the average low temperature, on the coldest day of the year for each of these cities is well within the normal operating range of the Toshiba-Carrier system. (Graphics: add the curves from weatherspark to show the difference between average & design.) Design for Seattle is 5F, Billings is -20F, Chicago -10F, and Nashville is 0F) “Avg. winter low in Chicago, IL is 17F” “Avg. winter low in Nashville, TN is 29F”

36 Heating Design Heating Design Strategies-Aux Heat Types of Aux. Heat:
Electric Strip-Heater (Ducted Models only) Hydronic Coil (can feed from an upsized DHW source) Both of above can be placed in DOAS ducting for 90+F ventilation air if that meets the needed BTU’s! Baseboard Heating Panels Hydronic or Electric-All Fan Coils Radiant Panels Wall Heaters Typically Electric-All Fan Coils Or….Previously Existing Heating System!! Graphics:Swoop in with the different kinds of Heat System pictures? Or highlight A-G sequentially.

37 Heating Design Heating Design Strategies-Aux Heat
There are 3 ways to activate the Aux. Heat Individual Space Response: Zone temp drops, Aux heat activates at Temp. A, then deactivates at Temp B. Both must be less than heating setpoint Outdoor Ambient Trigger. Aux heaters engage when FC is in Heating, Aux Heating system activated by separate Outdoor Ambient Thermostat. BMS Control system activation. Can use custom logic for zone by zone response, minimize setpoint drift. Graphics: A: Need graphic to show setpoint, Trigger point A, then release point B(use brent’s dwg). For B, show one of the weatherspark graphs with a line through it, showing below the line, the Aux. heat is always on if the FC is heating. Not sure if C needs one? Discuss custom respones like reducing setback below a certain ambient temperature, or if a zone tends to be colder, releasing setback earlier than with other zones?

38 Heating Strategies Heating Design Strategies-Aux Heat
Heating Setback with VRF: A VRF system is different from a combustion heater because it’s efficiency gets better at part-load. When system is in recovery, system goes to full-load, which is less efficient than maintaining a constant temperature, but total heat loss is more. So, optimum use is probably minimal setback during weekdays, and more of a setback over weekends & Holidays, or just a 2F setback period. No setback during cold snaps to avoid using Aux Heat.

39 Heating Strategies Heating Design Strategies-Aux Heat
Alternate to zone-level Aux. Heat-Put Outdoor Units in a Mechanical Room or “Doghouse” Graphics:show a simple shed, w/ Unit heater & discharge ducts, dampers

40 Heating Design Heating Design Strategies-Aux Heat
Alternate to zone-level Aux Heat-Put Outdoor Units in a Mechanical Room or Doghouse: Simplifies controls of Aux. Heat by having one set of controls and heat source. Heater is typically a Gas unit heater, or other combustion unit Backup isolates from Outdoor air at preset ambient temp. Key Selection Criteria: Size the Unit heater for 70-80% of Heat Load Ducting system must be 0.2” esp max. in both modes Activation temp typically below freezing, but maintain interior temp around 45F to avoid frost buildup. Don’t forget to include a condensate drain, w/heat tracing Graphics:show a simple shed, w/ Unit heater & discharge ducts, dampers

41 Refrigerant system Design VRF and ASHRAE 15/34
In part, Standard 15, Safety Standard for Refrigeration Systems, strives to ensure a safe system by limiting the maximum quantity of refrigerant below that which is a danger to human occupants if a leak occurs. Because VRF uses the Refrigerant as the transport medium, it is inherently a more refrigerant intensive product than most traditional HVAC. Std. 15 is the application guideline that ensures a safe design every time.

42 VRF and ASHRAE 15/34 Refrigerant Concentration Limit (RCL) R410A
R410A is a commonly used refrigerant for commercial VRF systems. Per Standard 34, Table 2, the safety classification of R-410A is Group A1 (meaning non-flammable and non-toxic). Even though R-410A is Group A1, its ability to displace oxygen could pose a danger to occupants if released in large quantities into smaller-volume spaces. Therefore, Standard 34, Table 2 has established an RCL for R-410A at 26 lbs of refrigerant per 1,000 cuft of room volume. For Institutional Occupancies such as patient care areas of hospitals and senior homes, the RCL is cut in half, changing the RCL for R-410A to 13 lbs/1,000 cuft.

43 VRF and ASHRAE 15/34 Smaller Capacity Systems
Design for “Connected Spaces” Combine multiple smaller zones on a single ducted fan coil unit One to-One Systems Diversity Refrigerant Piping Layout Y-branching versus manifold Isolate refrigerant circuit for Smaller Rooms R410A sensor and alarm, or isolation valves Stephen W. Duda’s article published in ASHRAE Journal, July Posted at Applying VRF? Don’t Overlook Standard 15

44 Questions ?

45 Thank You

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