Our manufacturer's recommendation for calibration is as follows:

• Retrotec fans: Every 5 years.  
• DM-2 Manometer: Every 2 years  or if the Manometer fails a field check. 
• DM32 / DM32 WiFi Manometer: Every 5 years or if the Manometer fails a field check.

Please review the DM32 and DM-2 Manuals on how to perform a field check.  

This only covers our manufacturer recommendation.  The energy standards (EN13829, ASTM, ATTMA, USACE, etc...) that you are using for test results may have different calibration intervals.  Please consult the energy standards for the specific equipment calibration intervals.