RC draught regulator (acc to DIN 4795 norm) - device that is to be mounted next to the chimney connection, equipped with a damper with an adjustable weight. The weight is to be regulated to achieve and maintain a certain underpressure ratio. After the certain weight is determined and chimney duct is too big, damper opens and lets some air into the duct - lowering underpressure to the level desired.

Product available in round (150mm diameter), rectangular (140x140mm) and fitted to Darco chimney clean out element versions at very competitive prices...