Bosch Worcester 28CDi User Instructions page 4

Fig. 1. System Diagram.
Automatic air
vent
Circulating
pump
Water to
water heat
exchanger
Diverter valve
CH
flow
4
Hot Water Mode:
The appliance operates to supply only domestic hot water when
the heating temperature mode is fully anti-clockwise, at the – posi-
tion or the timer is programmed to OFF mode.
A flow restrictor is fitted within the appliance which limits a hot
water delivery rate to a maximum of:
Hot Water and Central Heating mode:
Boiler
Domestic Domestic CH
hot water cold sup- return
out ply
24CDi 9.0 (±15%) litres/minute
28CDi 10.0 (±15%) litres/minute
35CDi II 12.0 (±15%) litres/minute
Gas to water
heat exchang-
er
Expansion
vessel
Pressure
relief valve
Safety dis-
charge
When a demand is made
for heating by the system con-
trols (i.e. a programmer or
room thermostat), the pump
will energise, circulating pri-
mary water around the heat-
ing system and the burner
will light. The heat output
from the appliance in this
mode has been factory set to
maximum. The appliance will
operate as necessary to main-
tain the temperature of the
radiators at the level set by
the adjustment of the Heating
Temperature Control Knob.
(See Fig. 2.)
If the system no longer
requires output to maintain
the desired room tempera-
ture, the burner will extin-
guish. The pump will contin-
ue to run for a short period to
dissipate the residual heat
from the appliance and then
switch off.
The appliance will sup-
ply heat to the central heating
system as required. A demand
for hot water at a tap or show-
er will override the central
heating function for the peri-
od of the domestic hot water
demand.