Safety Considerations for VRF Applications

January 13, 2012

Presenter:Dominic Kolandayan

Daikin AC (Americas), Inc.

Not intended as a substitute for the National, State and Local codes

The information contained herein is provided for general guidance and informational purposes only and is not a substitute for complying with all national, state and local codes as may be required. Every HVAC installation varies in its individual circumstances and the local, authorized engineer and/or installer will have to use their professional judgment in each installation for code compliance.

The contents herein are NOT approved by ASHRAE and does not imply an ASHRAE endorsement (per ASHRAE’s Policy).

IMPORTANT NOTICE AND DISCLAIMER

Introduction - what is VRF?

Safety considerations for VRF systems Occupancy Classification (ASHRAE 15, Section 4) Refrigerating System Classification (refer to ASHRAE 15, Section 5) Refrigerant Safety Classification (refer to ASHRAE 34, Section 6) Refrigerant Concentration Limits (refer to ASHRAE 34, Tables 1 & 2) Installation Restrictions (refer to ASHRAE 15, Section 8)

Application examples

Compliance responsibilities

Future safety considerations (flammable refrigerants)

Questions

Topics for this session

Variable Refrigerant Flow (VRF) systems are basically a variation of the ductless mini-splits that many HVAC professionals are already familiar with.

VRF Multi-split systems consist of the following matched components: a) an outdoor unit with single or multiple compressors or

variable capacity compressor or with a variable speed drive;

b) indoor unit(s) that have a coil, air movement device intended for single zone air distribution, and a temperature sensing control; and

c) a zone temperature control device.

Outdoor units can be air-cooled or water-cooled; indoor units can be non-ducted, ducted or mixed.

Introduction - what is VRF?

VRF system – example - Mixed

Safety Standard Compliance for VRF and any DX systems are the same.

Most state and local building codes reference ASHRAE 15 as the Safety Standard and to other standards referenced in ASHRAE 15 for safety.

One of the standards that users must also review is the most recent version of ASHRAE 34 for refrigerant safety classification and refrigerant concentration limit (RCL) information.

Important sections in ASHRAE 15 and 34 are: Occupancy Classification (refer to ASHRAE 15, Section 4) Refrigerating System Classification (refer to ASHRAE 15, Section 5) Refrigerant Safety Classification (refer to ASHRAE 34, Section 6) Refrigerant Concentration Limits (RCL) - refer to ASHRAE 34, Tables 1 & 2 Installation Restrictions (refer to ASHRAE 15, Section 8)

Safety considerations for VRF systems?

Safety considerations for VRF systems?

Figure 1 reprinted with permission: User’s Manual for ANSI/ASHRAE Standard 15-2001. © American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org.

How to apply Standard 15 to VRF systems

Occupancy classification (Standard 15, Section 4)

Considers the ability of people to respond to potential exposure to refrigerant:

- Public assembly - Residential

- Commercial - Large mercantile

- Industrial - Mixed- Institutional

Refrigerating System classification for VRF (Standard 15, Section 5)Method employed for extracting or delivering

heat:- a direct system (Std 15, Section 5.1.1)

Figure 1 Refrigerating system designation.

Degree of probability that a leakage of refrigerant will enter an occupancy-classified area:

- a high-probability system (Std 15, Section 5.2.1)

Figure 1 reprinted with permission: 2010 ANSI/ASHRAE Standard 15-2010. © American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org.

Refrigerant Safety Classification for VRF (Standard 34, Section 6)

Most VRF systems are designed for use with R410A which belongs to Safety Group Class A1.

Figure 1 reprinted with permission: 2010 ANSI/ASHRAE Standard 34-2010. © American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org.

Refrigerant Concentration Limit (RCL) for VRF (Standard 34, Tables 1 & 2)Most VRF systems are designed for use

with R410A.

RCL for R410A is code dependant.

Kentucky Building Code (KBC) 9th edition 2007, Revised November 2011, with a mandatory enforcement date of February 1, 2012 has adopted the 2006 IMC.

RCL in 2006 IMC is 10 lb/1000 cubic feet.

KBC Chapter 1, Administration, Section 102.4 Referenced codes and standards. The codes and standards referenced in this code shall be

considered part of the requirements of this code to the prescribed extent of each such reference. Where differences occur between provisions of this code and referenced codes and standards, the provisions of this code shall apply; and newer editions of any standards may be used to meet the intent of the code in lieu of the adopted edition.

RCL in ASHRAE-34-2010, adddendum L is 26 lb/1000 cubic feet. Responsible engineer can make a case to the AHJ (authority having

jurisdiction) to accept & approve the use of 26 lb/1000 cubic feet based on the latest info from Standard 34, addendum “L” to 34-2010.

Refrigerant Concentration Limit (RCL) for VRF (KBC Chapter 1)

Installation Restrictions

Std 15, 8.9 Refrigerant Pipe Joint InspectionField installed refrigerant pipe joints shall be exposed

for visual inspection before they are covered or enclosed.

Std 15, 8.10 Location of Refrigerant Pipingshall not be less than 7.25 ft above the floor in a

passageway unless the piping is located against the ceiling of such space and is permitted by the AHJ.

shall not be placed in any elevator, dumbwaiter, or other shaft containing a moving object; shall not be installed in an enclosed public stairway, stair landing, or means of egress.

Questions

6 ton condensing unit

12,000 Btu/h FCU

Smallest Occupied space

12’ x 12’ x 9’

= 1296 ft3

Application example – 6 ton system

• R-410A Refrigerant– Max ref charge = 26.0 lb / 1000 ft3 X 1296 ft3.

= 33.69 lb (do not round up) 33.69 lb = Max allowed in the entire system including

refrigerant piping

Max ref charge = Max concentration x Volume of smallest occupied space.

Refrigerant Charge Calculation

Occupied space = Smallest air tight room volume

Occupancy example # 1

Occupied space = Total room volume

Occupancy example # 2Multiple indoor units per zone

Occupied space = Volume of both rooms

Occupancy example # 3Partition example

Occupied space = Volume of both rooms

Ducted unit

Occupancy example # 4Ducted example

Designing consultant engineer and/or contractor is responsible for assessment and compliance.

Refer to the “User’s Manual for ASHRAE Std 15” which has examples, explanations and supporting references.

Compliance responsibilities

Refrigerant Safety Classification for VRF (Standard 34, Section 6)

Future safety considerations for VRF (flammable refrigerants)

Figure 1 reprinted with permission: 2010 ANSI/ASHRAE Standard 34-2010. © American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., www.ashrae.org.

Questions?