Vokera combination Boilers and water Heaters use a rubber diaphragm to trigger the domestic hot water by diverting the primary water circuit to the plate heat exchanger. This gives hot water to the taps or perhaps a shower. One side of the diaphragm is subject to indirect heat via the hot water in the primary circuit flowing through the hydraulic assembly. This design is common in combination boilers and other water-central heating appliances.

Brand Name	Vaillant