4
A flow restrictor is fitted within the appliance which limits the
hot water delivery rate to a maximum of 8.0 (±15%) litres/minute
(1.8 gallons/minute) 24i or 10 (±15%) litres/minute (2.2 gallons/minute)
28i.
Hot Water and Central Heating mode:
When a demand is made for heating by the system controls (i.e. a
programmer or room thermostat).
The pump will energise circulating primary water around the
heating 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 maintain 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 temperature,
the burner will extinguish.
The pump and fan will
continue to run for a short
period to dissipate the
residual heat from the
appliance and then switch off.
The appliance will supply
heat to the central heating
system as required. A demand
for hot water at a tap or
shower will override the
central heating function for
the period of the domestic hot
water demand.
Fig. 1. System Diagram.
Automatic
air vent
Gas to water
heat
exchanger
Circulating
pump
Fixed
by-pass
Flow
switch
CH
return
Domestic
hot water
out Domestic
cold
supply
Safety
discharge
Pressure
relief valve
Boiler
Expansion
vessel
CH
flow
