4
A flow restrictor is fitted within the appliance which limits a hot
water delivery rate to a maximum of 18 (±15%) litres/minute (4.0
gallons/minute).
The restrictor is removed by the installer if a cistern feed hot
water system is installed.
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 water diverter valve will open, 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 will have
been set by the installer to match the requirements of the system. 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 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. When domestic hot water is no
longer required the burner and
pump will continue to operate
until the heatbank is back to the
required temperature.
The appliance will return to the
central heating state and its
normal mode of operation.
Similarly the hot water is
occasionally diverted from the
central heating system into the
heatbank to maintain the stored
primary hot water temperature.
NOTE: If in doubt about the use
of the controls ask your installer
to assist you.
Fig. 1. System Diagram of Highflow 400 Series.
Primary
Water
circulation
Water
diverter
valve
From
radiators Mains
cold in
Flow
switch
Domestic hot
water out
Expansion
vessel
Slot in
front cover.
(O.F. only
Pilot
observation
window.
(B.F. only)
To
radiators
Circulating
pump
Heat
exchanger
Heatbank
Burner
Boiler
