|Size (mm)||320 x 180|
The way a bi-thermal draught regulator operates: when the body of the boiler warms up and spreads, the body closes a damper a little bit of fully trough a lever, and when the body cools, it shrinks and opens.
When metal and water warms up, a boiler cylinder becomes longer and lowers the damper. When you clean the ashes, it is useful to close the air damper. When you buy a boiler, the air damper is attached to the top of the boiler. It can be purchased separately too.