Mira Zest 7.5 Installation, Operation And Maintenance Manual page 10

12. When installed in very hard water areas (above 200 ppm temporary hardness) your
installer may advise the installation of a water treatment device, to reduce the
effects of limescale formation. Appliance malfunction due to excessive limescale
formation is not covered by the manufacturer's guarantee. Your local water company
will be able to advise the hardness of water in your area.
13. A hose retaining ring is supplied to prevent the handset from dropping below the
spillover level of the bath or shower, which could lead to contamination from back-
siphonage (refer to Figure 1). The supplied hose retaining ring should meet the great
majority of user requirements for shower installations with flexible outlet fittings.
However, there will be occasions when the hose retaining ring will not provide a
suitable solution. In these instances an outlet double checkvalve, e.g. the Mira
DCV-H, must be fitted. The inclusion of the Mira DCV-H will increase the required
supply pressure typically by 0.1 bar.
Double checkvalves, fitted in the inlet supply to the appliance, cause a pressure
build-up, which could exceed the maximum static inlet pressure for the appliance.
14. Water flow can be obtained without the electrical power being connected. This allows
the plumbing connections to be tested prior to final connection of the electrical
supply.
15. Avoid layouts where the shower hose will be sharply kinked. This may reduce the
life of the hose.
10
Hose Retaining
Ring
25 mm Minimum
Spill-over
Level
Figure 1