Installation Instructions

Inspection and maintenance | 35
6 720 805 218 (2016/02)SB625WS/SB745WS
8.4.2 Sealed unvented systems
For sealed unvented systems, the pressure gauge needle should be near
the mid point of the gauge. The red needle of the pressure gauge must be
set to the pressure required for the heating system.
▶ Check the heating system water pressure.
▶ Top up with water via the filling valve in the heating system pipework.
▶ Vent the heating system.
▶ Check the water pressure once more.
NOTICE: System damage through frequent topping up.
Subject to the water quality, your heating system can be
damaged through corrosion or scaling.
▶ Ensure that the heating system is vented correctly.
▶ Check the heating system for leaks and the
expansion vessel for functionality.
▶ Observe the requirements regarding water quality.
▶ If water loss occurs frequently, locate the cause and
rectify the problem without delay.
NOTICE: System damage through temperature
stresses.
▶ Only fill the heating system when cold (the flow
temperature must not exceed 104 °F (40 °C)).
▶ During operation, only fill the heating system via the
fill valve in the heating system pipework (return).