Frost Protection; System Pressure - Worcester GREENSTAR HEATSLAVE II External 12/18 User Instructions

Using your boiler

3.2.7 Frost protection

▶ The boiler has built in frost protection to protect the boiler,
the boiler must have power for this to operate.
▶ If you are leaving the property unoccupied during cold
weather, please leave your programmer on constant and
your room thermostat set to 15°C.
▶ If the temperature within the boiler falls below 8°C the
pump will run to circulate water and prevent the system
freezing.
▶ If the temperature within the boiler falls below 4.5°C the
boiler will fire immediately, bringing the boiler temperature
up to 12°C to avoid the possibility of the system freezing.
▶ This process will be repeated until such time that the boiler
temperature does not drop below 4.5°C.

3.2.8 System pressure

This boiler is fitted to a sealed heating system which is pre-
pressurised. Your installer will advise you of the minimum and
maximum pressure indicated on the pressure gauge.
▶ Check regularly that the pressure is maintained.
Fig. 6
Optimum system pressure when your boiler is cold (area A) and
the pump is off. The indicated pressure will change as the pump
switches on, for more accurate readings check pressure when
the pump is not running.
▶ Contact your installer or maintenance engineer if a
permanent significant decrease or increase in pressure is
indicated on the pressure gauge.
8
Filling loop
If the sealed system pressure within your system drops to
below 0.5 bar (shown on the pressure gauge) you will need to
increase the pressure to ensure your boiler continues to run
without problems.
Your installer should have informed you where
to find the filling system and instructed you in
its use.
Once the external filling loop has been located, follow the
instructions for re-pressurising the system.
1. Unscrew blanking cap.
2. Attach the hose to the valves, screw on hand-tight.
3. Turn the handle/screwdriver slot through 90° to open
valves.
4. The handle/screwdriver slot will be in line with the valves.
5. When the pressure reaches between the 1 and 1.5 bar
marks (zone A), turn the handles/screwdriver slots back,
through 90°, to close the valves.
6. The handle/screwdriver slot will be at 90° to the valves.
7. Remove the hose and replace the blanking caps.
Fig. 7
Greenstar Heatslave II External ErP – 6 720 813 722 (2014/09)