Low Pressure Indication; Constantly Re-Pressurising The System; Semi-Sealed Heating System; Topping Up The System Pressure - Bosch Condens 4700iW User Instructions

Prepare for operation
▶ Check the system pressure on the display.
– Indicator in red zone: pressure is too low or too high.
– Indicator in yellow zone: pressure is low or slightly too high.
– Indicator in green zone: pressure is normal.
▶ Top up the heating water, if the pressure is low or too low.
3.1.2

Low pressure indication

Low pressure (shaded area [A]) will be indicated on the appliance:
• The pressure indicator is within the area between 0 and 0.79 bar in
the pressure menu display (left hand yellow and red zone).
• Additionally there is a message displayed.
Fault - 1017
System pressure
Pressure: 0.2 bar
Min
A
Fig. 3 Low pressure indication
[A] Low pressure area
3.1.3

Constantly re-pressurising the system

Constantly having to re-pressurise the heating system should be
investigated as it is an indicator of potential leaks and the concentration
of inhibitor protection in the system will be reduced; this can result in
corrosion within the heating system, reducing efficiency and increasing
contaminates.
▶ Check for leaks on heating system (pipework and radiator valves).
▶ Contact your installer or maintenance engineer if a recurring
significant decrease or increase in pressure is shown on the pressure
indicator (pressure gauge or pressure display).
System pressure increasing:
▶ If the system pressure repeatedly increases and you need to vent air
from the radiators, refer to  section 9.4 "System gassing
troubleshooting", page 16.
3.2

Semi-sealed heating system

A semi sealed heating system is filled and automatically topped up from
a header tank. There will be no filling link provided for topping up the
system.
Appliances which are suitable for use on a semi sealed system will be
capable of operating at very low system pressures, this may be displayed
as 0 pressure on the appliance display.
▶ The system will be automatically topped up, there is no means of
increasing system pressure with a filling link.
▶ The appliance will not display a low pressure fault, even if the system
is empty or fails to top up. Low water content in the system may lead
to an over-heat lockout.
▶ If you regularly have to vent air from radiators, or suspect a leak from
anywhere on the heating system this must be investigated and
remedial work carried out. Inhibitor levels must be checked and
replenished if necessary.
6
too low
Max
3.3

Topping up the system pressure

Sealed heating system
Your installer should have informed you where to find the filling system
and instructed you in its use.
NOTICE
System fill method
▶ You must remove the "filling key" or disconnect the external filling
loop after re-pressurisation, to comply with the Water Authority
regulations.
To aid in filling the system.
▶ Ensure the Central Heating is on.
Automatic filling facility
The automatic filling device refills the water into the heating system as
required. Your installer programmes the filling device according to your
heating system. Have your installer explain the function of the automatic
filling device to you.
Automatic refilling keeps the pressure in the heating system at the
programmed value.
Fig. 4 Automatic filling facility
Removal and replacement of bottom panel
To gain access to the filling link, remove the bottom panel.
Press in the tabs [A] and pull the bottom panel down to remove.
C
B
Fig. 5 Bottom panel
To replace the bottom panel, ensure that the tabs [B] line up with the
edges of the boiler [C] and push into place until the tabs [A] click into
place.
Condens 4700iW – 6721864484 (2023/04)
0010023397-001
C
A
0010036333-001
B