Why Spray Foam Can Trigger a Refrigerant Leak Detector

Great Stuff Spray Foam and False Leak Detector Readings

Great Stuff spray foam contains propellants and blowing agents that can temporarily set off certain refrigerant leak detectors. This happens because of vapors released before the foam cures. In some cases, this vapor interference can also cause the system to throw an error code—most commonly EH-C1. If this occurs, the code can be cleared by pressing the SW1 button on the control board for 10 seconds to reset it.

Why It Happens

Heated Diode Detectors
Designed to ionize halogenated refrigerants (chlorine or fluorine-based).
Some older or more sensitive models may react to hydrocarbons in high concentrations, causing a false positive.

Corona Discharge Detectors
Use a high-voltage electrical field to sense gases.
Not gas-specific—can be triggered by a wide range of vapors, including spray foam propellants.

Flammable Propellants in Spray Foam

Great Stuff uses isobutane, dimethyl ether, and propane as propellants.
These hydrocarbon gases can temporarily alarm leak detectors, especially corona discharge types.

Sensor Interference

Uncured foam vapors in high concentrations can overwhelm a sensor, mimicking a refrigerant leak.
This can sometimes lead to the EH-C1 error mentioned above if the system’s sensors are disrupted during or shortly after application.

How to Avoid False Readings

✔ Wait for the foam to cure – Vapors dissipate after curing. Always check the product SDS for off-gassing times.
✔ Ventilate the area – Proper airflow helps vapors clear faster.
✔ Keep sensors clean – Follow the manufacturer’s maintenance instructions to prevent contamination.
✔ Use an IR detector if available – Infrared detectors are refrigerant-specific and far less likely to be affected by hydrocarbons.