An eco-friendly boiler refers to a boiler whose flue gas emissions comply with national standards. It is not a specific product model but a broad concept, meaning any boiler meeting environmental requirements 

qualifies as eco-friendly.

Common eco-friendly boiler types include electric steam boilers, gas/oil-fired boilers, and biomass boilers.

Electric steam boilers use electricity as fuel. They produce no exhaust gases or emissions during operation, making them clean and environmentally friendly boilers.

Gas and oil boilers are currently mainstream products in the boiler market, occupying an important position. They use clean energy as fuel, and the nitrogen oxide content in their exhaust emissions after combustion 

complies with environmental policy standards, also qualifying them as environmentally friendly boiler products.

Biomass boilers primarily use biomass pellets as fuel, including materials such as straw, peanut shells, and wood chips. While some countries and regions classify biomass boilers as environmentally friendly, certain 

areas may restrict or prohibit their use.