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Solutions for Chiller Rooms

Refrigerant gas leak detection to meet ASHRAE 15 & 34 code

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Our Approach

Chiller rooms are essential for maintaining precise temperature control in industrial and commercial operations. However, these environments face serious safety and operational risks from refrigerant leaks, which can lead to hazardous conditions, reduced efficiency, and environmental harm.

At AGS Controls, our state-of-the-art refrigerant gas leak detection systems are designed to meet ASHRAE 15 & 34 code requirements for safety and compliance. Utilizing advanced infrared leak detector technology, our solutions deliver highly accurate monitoring and real-time alerts to detect refrigerant leaks swiftly. Whether you need an AC leak detector or the best refrigerant leak detector for your chiller room, AGS Controls provides reliable systems tailored to protect your facility.

Ensure safety, regulatory compliance, and operational efficiency with AGS Controls' refrigerant leak detection solutions, purpose-built for chiller rooms and critical refrigeration applications.

Our Solutions

MerlinGuard Gas Detection System with Remote Sensors


As refrigerant systems in chiller rooms become more prevalent, ensuring their safety and compliance with industry standards like ASHRAE 15 is critical. Refrigerant leak detection is essential for preventing leaks that could lead to dangerous situations, reduced system efficiency, and environmental harm. Our AGS Controls MerlinGuard system provides the best complete package for refrigerant leak detection in chiller rooms. It integrates seamlessly with up to sixteen AGSRTFT detectors, offering advanced gas detection with real-time alerts for early leak detection.


The system includes a pre-programmed control panel with features such as fan control, alarm damper control, and connectivity to Building Management Systems (BMS) for streamlined integration. With four output options for pre-alarm and high-alarm conditions, and a 0-10V output for BMS or fan control via VFD, MerlinGuard is the ideal solution to safeguard your facility, ensuring compliance with ASHRAE 15 and protecting your operations.

View Refrigerant Gas Leak Detectors

Code Requirements

8.9.5 Each machinery room shall contain a refrigerant detector, located in an area where refrigerant from a leak will concentrate, that actuates an alarm and mechanical ventilation in accordance with Section 8.9.6 at a set point not greater than the occupational exposure limit (OEL) value as published in ASHRAE Standard 34.³ For refrigerants that do not have a published OEL value in Standard 34, a set point determined in accordance with the OEL as defined by Standard 34 shall be approved by the AHJ. The alarm shall annunciate visual and audible alarms inside the machinery room and outside each entrance to the machinery room. The alarms required in this section shall be of the manual-reset type with the reset located inside the machinery room. Alarms set at other levels (such as IDLH) and automatic reset alarms are permitted in addition to those required by this section. The meaning of each alarm shall be clearly marked by signage near the annunciators.

8.11.6 Where any refrigerant of Groups A2, A3, B2, or B3 are used, the machinery room shall be designated as Class I, Division 2 hazardous (classified) electrical location in accordance with the National Electric Code® (NFPA 70).⁴

Where flammable refrigerants only from Groups A2L or B2L are used, the machinery room shall meet one of the following requirements:

a. Be provided with ventilation per Section 8.11.6.1 and refrigerant detection per Section 8.11.6.2.

b. Be designated as Class I, Division 2 hazardous (classified) electrical location in accordance with NFPA 70, and be provided with ventilation per Section 8.9.6 and refrigerant detection per Section 8.11.6.2. Compliance with Section 8.11.11 shall not be required.

8.11.6.1 The machinery room shall have a mechanical ventilation system in accordance with Section 8.11.11. The mechanical ventilation system shall

a. Run continuously, and failure of the mechanical ventilation system actuates an alarm or

b. Be activated by one or more refrigerant detectors, conforming to requirements of Section 8.11.8

8.11.6.2 Detection of refrigerant concentration that exceeds 25% of the lower flammability limit (LFL) or the upper detection limit of the refrigerant detector, whichever is lower, shall automatically de-energize the following equipment in the machinery room:

a. Refrigerant compressors

b. Refrigerant pumps

c. Normally closed automatic refrigerant valves

d. Other unclassified electrical sources of ignition with apparent power rating greater than 1 kVA, where the apparent power is the product of the circuit voltage and current rating

8.11.7 Remote control of the mechanical equipment in the machinery room shall be provided immediately outside the machinery room door solely for the purpose of shutting down the equipment in an emergency. Ventilation fans shall be on a separate electrical circuit and have a control switch located immediately outside the machinery room door.

8.11.8 Each machinery room in accordance with Section 8.11 shall contain one or more refrigerant detectors in accordance with Section 8.11.9, with sensing element located in areas where refrigerant from a leak will concentrate, with one or more set points that activate responses in accordance with Section 8.11.10 for alarms and Section 8.11.11 for mechanical ventilation. Multiport-type devices shall be prohibited.

8.11.8 Each machinery room in accordance with Section 8.11 shall contain one or more refrigerant detectors in accordance with Section 8.11.9, with sensing element located in areas where refrigerant from a leak will concentrate, with one or more set points that activate responses in accordance with Section 8.11.10 for alarms and Section 8.11.11 for mechanical ventilation. Multiport-type devices shall be prohibited.

8.11.9 Refrigerant detectors required by Section 8.11.8 shall meet all of the following conditions:

a. A refrigerant detector shall be capable of detecting each of the specific refrigerant designations in the machinery room.

b. The refrigerant detector shall activate responses within a time not to exceed a limit specified in Sections 8.11.10 and 8.11.11 after exposure to refrigerant concentration exceeding a limit value specified in Sections 8.11.10 and 8.11.11.

c. The refrigerant detector shall have a set point not greater than the applicable OEL value as published in ASHRAE Standard 34.³ The applicable OEL value shall be the lowest OEL value for any refrigerant designation in the machinery room. For refrigerants that do not have a published OEL value in Standard 34, use a value determined in accordance with the OEL as defined by Standard 34 where approved by the AHJ.

d. The refrigerant detector shall have a set point not greater than the applicable refrigerant concentration limit (RCL) value as published in ASHRAE Standard 34.³ The applicable RCL value shall be the lowest RCL value for any refrigerant designation in the machinery room. For refrigerants that do not have a published RCL value in Standard 34, use a value determined in accordance with the RCL as defined by Standard 34 where approved by the AHJ.

e. The refrigerant detector shall provide a means for automatic self-testing and shall be in accordance with Section 8.11.10.4. The refrigerant detector shall be tested during installation and annually thereafter, or at an interval not exceeding the manufacturer’s installation instructions, whichever is less. Testing shall verify compliance with the alarm set points and response times per Sections 8.11.10 and 8.11.11.

8.11.10 Alarms required by Section 8.11.8 shall comply with the following.

8.11.10.1 The alarm shall have visual and audible annunciation inside the machinery room and outside each entrance to the machinery room.

8.11.10.2 The refrigerant detector set points shall activate an alarm in accordance with the type of reset in Table 8-1. Manual-reset type alarms shall have the reset located inside the machinery room.

8.11.10.3 Alarms set at levels other than Table 8-1 (such as IDLH), and automatic reset alarms, are permitted in addition to those required by Section 8.11.10. The meaning of each alarm shall be clearly marked by signage near the annunciators.

8.11.10.4 In the event of a failure during a refrigerant detector self test in accordance with Section 8.11.9(e), a trouble alarm signal shall be transmitted to an approved monitored location.

8.11.11* Ventilation. Machinery rooms, in accordance with Section 8.11, shall be vented to the outdoors using mechanical ventilation in accordance with Sections 8.11.11.1 through 8.11.11.4.

8.11.11.1* Mechanical ventilation referred to in Section 8.11.11 shall comply with the following:

a. Include one or more fans capable of exhausting air from the machinery room.

b. Include makeup air provisions to replace air being exhausted.

c. Ducts for supply to and exhaust from the machinery room shall serve no other space.

d. The makeup air supply locations in the machinery room shall be positioned relative to the exhaust opening locations within the machinery room to avoid short circuiting of ventilation airflow within the machinery room.

e. Inlets to the exhaust openings or ducts shall be located where leaked refrigerant will concentrate.

f. The bottom edges of inlets to exhaust openings or ducts shall be within 1.00 ft (0.30 m) of the floor at locations identified per Section 8.11.11.1(e).

g. Where the machinery room contains refrigerants with relative molar mass less than 42.0, additional inlets to exhaust openings or ducts shall be within 1.00 ft (0.30 m) of the highest point of the machinery room.

h. The discharge of the exhaust air shall be to the outdoors in such a manner as not to cause a nuisance or danger.

i. Mechanical ventilation systems used to exhaust refrigerant shall not be combined with combustion venting systems.

j. Electric motors driving fans shall not be placed inside ducts; fan rotating elements shall be nonferrous or nonsparking, or the casing shall consist of or be lined with such material.

8.11.11.2 Level 1 Ventilation. When personnel are present, the machinery room mechanical ventilation in Section 8.11.11.1 shall automatically or manually exhaust at an airflow rate not less than 0.50 ft³/min/ft³ (0.0025 m³/s/m³) of machinery room area.

8.11.11.3 Level 2 Ventilation. When triggered by the refrigerant detector of Section 8.11.8, at a set point and response time in accordance with Table 8-1, the machinery room shall be ventilated automatically to supply not less than the airflow determined in accordance with Section 8.11.11.4.

When multiple refrigerant designations are in the machinery room, evaluate the required airflow according to each refrigeration system, and the highest airflow quantity shall apply.

Ventilation reset shall be in accordance with the type of reset in Table 8-1. Manual-type ventilation reset shall have the reset located inside the machinery room.

8.11.11.4* Safety Group A2L, B2L. When required by Section 8.11.11.3, the total airflow for Level 2 ventilation shall be not less than the airflow rate determined by either the graphical method of Figures 8-1 (I-P) and 8-2 (SI) or the calculation method using the equations in Table 8-2. The total airflow rate for Level 2 ventilation shall not be less than Level 1 ventilation. The airflow rate (Q) per the calculation method shall be rounded up to the nearest value to assign equipment.

ASHRAE 34 Refrigerant Concentration Limit (RCL)

The RCL is the maximum concentration of refrigerant allowed within a defined space, measured in lb/1000 ft³. It indicates the point where the refrigerant concentration becomes hazardous.

Purpose: Prevent dangerous refrigerant leaks in occupied spaces.

Key Concept: If a system’s refrigerant charge exceeds the RCL in a given space, a detection system and compliance with machinery room standards are required.

Sections Referenced: 7.2: Volume calculation (effective dispersal volume). 7.3: Maximum charge allowed in the system. 7.4: Specifies that systems with refrigerant amounts above the limit must be located outdoors or in a machinery room.

Refrigerant Types and Applicable Code Sections

Refrigerant Type

Applicable Sections

A1, B1

Section 8.9

A2, A3, B2, B3

Sections 8.9 and 8.10

A2L, B2L

Sections 8.9.1–8.9.4, 8.11

Machinery Room Refrigerant Detector Requirements (2024 & 2022)

Every machinery room must include a refrigerant detector positioned where refrigerant leaks are likely to concentrate. The detector must trigger an alarm and mechanical ventilation as outlined in Section 8.9.6. The activation set point must not exceed the Occupational Exposure Limit (OEL) defined in ASHRAE Standard 34. If no OEL is listed, the set point must be approved by the Authority Having Jurisdiction (AHJ) according to ASHRAE guidelines.

The system must display visual and audible alarms both inside the room and at all entrances. Manual-reset alarms are required, with the reset control located inside the room. Additional alarms, such as for immediately dangerous to life or health (IDLH) levels or automatic reset alarms, may be used alongside the manual-reset system. Signage must clearly describe the purpose of each alarm.

Key Requirements and Guidance:

Detector Placement: Determine if the refrigerant will rise or sink based on its weight relative to air. Place detectors at appropriate heights as specified in the AGS manual (e.g., near the floor for heavier refrigerants, near the ceiling for lighter ones). Detectors may be wall-mounted near equipment such as chillers or ceiling-mounted at high-risk areas.

Alarm and Ventilation Activation: Ventilation must engage at a flow rate of 100 times the square root of the refrigerant charge (Section 8.9.8.1). Ensure the ventilation system effectively removes leaked refrigerant to maintain safety levels.

OEL Alarm Set Point: The OEL represents the allowable time-weighted average (TWA) concentration over an eight-hour workday. Reference OSHA Permissible Exposure Limit (PEL), ACGIH Threshold Limit Value (TLV), or equivalent values as detailed in ASHRAE Standard 34.

Visual and Audible Alarms: Install alarms inside the machinery room and outside each entrance. Alarms can connect to a control panel or use built-in strobes for clear visual signaling.

Manual Reset: The AGS MerlinGuard system requires a manual reset after a high-level alarm, with the reset located inside the machinery room. This ensures personnel are present to assess the situation before the system resets.

Proper configuration and maintenance of refrigerant detection and alarm systems help mitigate risks associated with refrigerant leaks.

A2L Type Refrigerant Detection Code

Chapter 8, Section 11 (2024) outlines machinery room requirements for systems using A2L refrigerants. Below is a summary of the key provisions:

Electrical Hazard Classification (8.11.6) For A2L refrigerants, the machinery room must meet one of the following: include ventilation per Section 8.11.6.1 and detection per Section 8.11.6.2, or be designated as a Class I, Division 2 hazardous location (per NFPA 70) with ventilation and detection systems in place.

Ventilation System (8.11.6.1) Must operate continuously or be activated by refrigerant detectors. Alarms must trigger if the ventilation system fails. If two stage ventilation is used, stage one is no greater than OEL limit, and stage two is no greater than 25%LFL.

Detection Requirements (8.11.6.2) Detection is required if refrigerant levels reach 25% of the Lower Flammability Limit (LFL) or the detector’s upper limit, whichever is lower. When these limits are reached, systems must automatically shut down compressors, pumps, automatic refrigerant valves, and electrical ignition sources over 1 kVA. A supervisory alarm, or level one ventilation alarm must be provided prior to the OEL limit.

Emergency Shutdown (8.11.7) A manual shutdown control must be installed outside the machinery room. Ventilation fans must have independent control switches placed outside the room. The ventilation switch activates to level one exhaust level.

Refrigerant Detectors (8.11.8–8.11.9) Detectors must be placed where refrigerants could concentrate. Multiport detectors are prohibited. Detectors must detect all refrigerants used in the room, activate alarms within time limits outlined by the standard, be set to the lowest applicable OEL or RCL for refrigerants in use, and include automatic self-testing and annual maintenance.

Alarm Requirements (8.11.10) Alarms must have visual and audible signals inside and outside the room. Manual reset alarms must be reset from inside the machinery room.

AGS Compliance

AGS detection systems, such as MerlinGuard, comply with these requirements by integrating self-testing detectors, manual-reset alarms, and remote fan control for enhanced safety and compliance.

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