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INSTALLATION & SERVICING INSTRUCTIONS
47
DOMESTIC HOT WATER FLOW FUNCTION
6-720-611-730b (12.05)
DOMESTIC HOT WATER FLOW
FUNCTION
NOTE: This diagram is a simplification of the
function of the boiler (for example; the hot water
demand is a complex decision based on flow rates
and existing temperatures etc.).
MAIN SWITCH
ON
GREEN LIGHT
ON
Tank demand
(overrides central
heating demand).
Hot water demand
(overrides all other
demands).
Pump ON.
Diverter valve to
hot water position.
Ignition sequence.
Modulate fan (heat
input) to charge
tank to temperature
set by user control
(65°C - 75°C).
Minimum heat
input until 50°C if
boiler unused for
long period.
Tank satisfied.
Check tank
temperature.
Is it still near set
point?
Ignition sequence.
Modulate fan (heat
input) to maintain
delivered
temperature set by
user control (45°C
- 65°C).
Delivered
temperature too
high.
End of demand.
Gas valve OFF
until temperature
drops to set level.
YES
NO
GAS VALVE OFF.
Continue fan 40
secs.
Continue pump 15
secs.