Viessmann Flow Switch For Vitodens B2Tb/B1Ha/B1Ka/B2Hb/B2Ha Series Boilers 7839747. Compatible with Vitodens 222-F B2TB 19/35 Series Residential Floor-Standing Gas-Fired Condensing Boilers Compatible with Vitodens 100-W B1HA/B1KA 26/35 Vitodens 200-W...