Why does my chimney or a combustion chamber emit smoke?
If aeration is higher than the chimney draught, the boiler will emit smoke. You need to investigate what is the purpose:
- inappropriate chimney (holes, pierces into other chimney ducts)
- too small height or section
- lack of insulation outside the chimney
- additional appliances connected to the same chimney duct
- polluted duct or boiler
- bad construction of an elbow or elbows (acute angles, too many elbows)
- lack of ascension of the flue duct (exhaust gases should flow slightly up after having left the boiler)
- flue duct too deeply in the chimney
- too big ventilation opening in the wall (it may generate opposite air direction)
Additionally, in boilers with an automatic aeration, air flow should be limited:
- by using a metal flap of a ventilator
- by setting up parameters in the steering of a boiler
-
SZS series gas-fired (oil-fired) steam boilerLive Chat2-110 t/h1.25-5.3 MPa
-
SZL series coal-fired steam boilerLive Chat6-35 t/h1-2.5 MPa
-
DHL series biomass-fired steam boilerLive Chat20-75 t/h1.25-5.4 MPa
-
Email us
-
WhatsApp: +86 18861589035
WeChat: +86 13506150756
Live Chat

-
Against the backdrop of accelerated global carbon reduction and increasingly stringent safety and environmental supervision, internationally recognized compliance qualifications have become an important foundation for industrial equipment manufacturers to expand into overseas markets. With ASME (American Society of Mechanical Engineers) certification as a core cornerstone, ZOZEN Boiler continues to advance the international upgrade of product compliance and engineering service capabilities, driv...13 Jan 2026 -
On January 6, Wuxi ZOZEN Boiler Co., Ltd. held its 2026 Annual Conference and the 2025 Commendation Ceremony for Advanced Teams and Outstanding Employees under the theme “United to Set Out — Uphold Integrity, Advance with Intelligence.” General Manager Zhang Guoping gathered with all employees to review the company’s journey, honor annual contributions, and chart the path forward. Looking back: Steady progress through perseverance and breakthroughsThe conference opened w...07 Jan 2026 -
In 2025, ZOZEN Boiler is leveraging a series of international exhibitions to continue cultivating overseas markets. From Asia’s Pakistan Textile Expo to Europe’s Russian HVAC and Boiler Exhibition and Industrial Boiler & Heat Exchange Exhibition, and onward to Serbia’s TOPS Scientific Seminar, ZOZEN showcased its high-efficiency, eco-friendly boiler products and customized energy solutions to global customers—demonstrating strong technological capability and market co...30 Dec 2025











