System Installation Requirements Flashcards

When installing refrigerant piping for an A2L system that penetrates two or more floors in a multi-story building, which of the following is a primary requirement according to the International Mechanical Code (IMC) and ASHRAE 15?

Answer: The piping must be enclosed in a fire-resistance-rated shaft.

To prevent the spread of flammable refrigerant and fire between floors in the event of a leak, both the IMC and ASHRAE 15 require that refrigerant lines penetrating two or more floors be enclosed in a fire-resistance-rated shaft. This contains any potential leak within a controlled, often ventilated, space.

A technician is installing a new A2L ducted system. To comply with UL 60335-2-40, what calculation must be performed to ensure the refrigerant charge is safe for the area being served?

Answer: Minimum conditioned space area (TAmin) calculation.

UL 60335-2-40, Annex GG, requires the calculation of the minimum conditioned space area (TAmin) to ensure that if the entire refrigerant charge were to leak into the space, the concentration would remain well below the lower flammability limit (LFL). This calculation is based on the total system charge and the refrigerant type.

During the installation of an A2L refrigeration system in a machinery room, the mechanical ventilation system must be interlocked with which other component to ensure safety in case of a ventilation failure?

Answer: The chiller and any associated alarm systems.

Safety standards require that the mechanical ventilation system be interlocked with the chiller (the refrigeration system) and alarm systems. In the event of a ventilation system failure, the chiller's operation must be stopped to prevent a potential refrigerant leak from accumulating, and an alarm must be initiated.

Which of the following is a specific requirement for the electrical components, such as relays and contactors, used in new HVAC equipment designed for A2L refrigerants, according to UL 60335-2-40?

Answer: They must be spark-mitigated or housed in flame-arresting enclosures.

To prevent the ignition of A2L refrigerant in case of a leak, UL 60335-2-40 mandates that electrical components that could create a spark must be specifically designed to mitigate this risk. This is achieved through methods like using spark-mitigated components or placing them inside enclosures that can contain an internal ignition without letting it spread.

A contractor is installing an A2L multi-split system where the refrigerant piping runs through a vertical pipe shaft. According to ASHRAE 15, if this shaft is mechanically ventilated, what event must trigger the activation of the ventilation fan?

Answer: A signal from a refrigerant sensor at the bottom of the shaft.

For mechanically ventilated shafts containing A2L refrigerant piping, ASHRAE 15 requires a refrigerant sensor to be placed at the lowest point of the shaft (as A2L refrigerants are heavier than air). If a leak is detected, this sensor must activate the mechanical ventilation fan to exhaust the refrigerant and prevent accumulation.

When installing a high-probability A2L system for human comfort, ASHRAE Standard 15 requires a Refrigerant Detection System (RDS). What action must occur within 15 seconds of the RDS detecting a refrigerant concentration above its setpoint?

Answer: The air circulation fan must be energized and zone dampers opened.

ASHRAE Standard 15-2022, Section 7.6.2.5, requires specific mitigation actions to occur within 15 seconds of a leak being detected by the RDS. These actions include energizing the air circulation fan and opening any zone dampers to help disperse the refrigerant and keep its concentration below the LFL.