Vacuum collectors are suitable, if there is an option of additional heating necessary, because of their higher output in transient and winter period
Included are double-wall glass vacuum tubes and copper pipes with heat transmitting liquid. Selective absorbing layer is created on the internal side of pipe. In order to use the radiance maximally, there is parabolic reflection glass placed behind the vacuum pipe. Vacuum ensures perfect high temperature isolating protection in copper tubes. Efficiency of these collectors is higher in transient and winter period. They can be used for D.H.W. preparation and also as a support of heating.