Automatic leak detection for supermarkets: direct vs. indirect, and EPA’s 1,500 lb rule.

The short version.

Under EPA’s AIM Act rule, commercial refrigeration systems holding 1,500 lb or more of HFC refrigerant must have automatic leak detection (ALD). New systems installed from January 1, 2026 need it within 30 days of installation. Systems installed from January 1, 2017 through December 31, 2025 need it by January 1, 2027.

ALD can be direct, using sensors that detect refrigerant in the air, or indirect, using system data to detect a loss of charge. Most grocery racks are below 1,500 lb and do not need ALD, but they are still covered by leak repair rules from 15 lb, so finding leaks early matters for every store.

Which systems need ALD.

Direct detection: sensors in the air.

Direct systems sample the air in machine rooms, walk-ins and near equipment and alarm when refrigerant concentration rises. They are good at telling you roughly where a leak is, and they matter for occupant safety in enclosed spaces.

Their limit is coverage. A sensor only detects refrigerant that reaches it. Leaks in sales-floor piping, cases, ceilings and rooftop runs can go unnoticed, and sensors need regular calibration and maintenance across every zone.

Indirect detection: the system’s own data.

Indirect systems analyze operating data such as receiver levels, pressures and temperatures to recognize a system that is losing charge. Because they watch the whole circuit rather than a room, they can catch slow losses anywhere in the system, including leaks no sensor would reach.

Their limit is location. Indirect detection tells you which system is losing refrigerant and how quickly, not where the leak is. A technician still finds it.

Direct vs. indirect at a glance.

What EPA expects from any ALD system.

Section 84.108 of the rule sets detection and alerting requirements for both direct and indirect systems, requires an annual audit and calibration, and requires records of alerts and the response to them. The detection thresholds differ by approach, so check the text of 84.108 against the system you are considering.

An ALD system that meets the rule can be used in place of the leak inspections otherwise required after a leak-rate exceedance.

Where KalderIQ fits.

KalderIQ provides indirect leak analytics from the data your Copeland E2 or E3, Danfoss or Micro Thermo controller already records. Each rack gets a leak probability, the method that raised it and an estimated leak rate, ranked across all your stores. In one distribution warehouse it flagged a loss within two weeks that three years of repairs had missed.

Whether a particular setup satisfies 84.108 for a 1,500 lb system is something we review with you system by system. For racks below 1,500 lb, which is most of a grocery estate, early detection is simply the cheapest way to keep leak rates, refrigerant costs and repair deadlines down.

Using both.

Many stores benefit from both: direct sensors where people work in enclosed spaces, such as machine rooms and walk-ins, and indirect analytics watching every system continuously. The two catch different leaks.