Code: DEP Triennial (legal requirement)
Description: This is a three-year renewal cycle for boiler registration with the NYC Department of Environmental Protection (DEP). Certain boilers must renew their DEP registration and submit a combustion test report every three years through the Clean Air Tracking System (CATS).
Practical Meaning: If your building has a boiler rated between 350,000 BTU/hr and 4.2 million BTU/hr, you must renew your DEP registration every three years. You need to hire a qualified technician to perform a combustion test and submit the results to DEP through the CATS online system. This is separate from your annual DOB boiler inspection—you must do both.
Where You May See It: You may see this term on DEP notices about upcoming registration renewals, in your CATS account online, on your existing boiler registration certificate (which shows the expiration date), in service contracts with your boiler maintenance company, or in ECB violation notices if you miss the deadline.
Why It Matters: Missing the triennial renewal deadline results in DEP violations and fines from the Environmental Control Board (ECB). Many building owners confuse the annual DOB boiler inspection with the separate three-year DEP registration requirement and accidentally skip the DEP filing. The triennial cycle starts from your last registration date, not the calendar year, so each building has its own deadline.