Worcester 28i RSF User Manual

28
Signal from the
flow turbine
HOT WATER
DEMAND
(Overrides all other
overrun modes
and functions)
No demand and
primary
temperature below
6°C monitored by
the central heating
sensor
Internal
"Autofrostat"
Demand
Run pump
Below 4°C
Above 8°C
4°C to 8°C
Monitor central
heating sensor
Burner pressure
at 1.5 mbar
Burner pressure adjusted
based on the temperature
rise over the previous
minute. Aiming at 4°C
rise/minute.
Burner never to be
extinguished
irrespective of the
rate of temperature
rise
At the set point
change to a wide
band proportional
control
Commence normal central
heating mode until heating
temperature reaches 20°C
Return to normal
OFF state
Pump on until
primary temperature
drops to 55°C
No demand and central
heating temperature above
50°C monitored by the
central heating sensor
End of demand or central
heating temperature above
70°C monitored by the
central heating sensor
Pump and Fan on
for 4 minutes
Inhibit operations
for approximately
1 second. 6 second
delay before re-
ignition from any
other demand.
Is the central
heating mode
interrupted?
AUTOMATIC
START-UP
SEQUENCE
HOT WATER
DEMAND
SATISFIED
Pump OFF
Wait for flow
greater than
2.9 l/min
Gas valve OFF.
Fan remains ON
Modulate heat
input to maintain
hot water
temperature at the
factory pre-set
level
Gas valve OFF
Operating
Switch (or
programmer
OFF)
Domestic hot water
temperature
monitored by hot
water sensor
3. "Autofrostat" Function
4. Pump Overrun Function
5. Over run Function
2. Domestic Hot Water Mode
6. Central Heating ramp control
Flow less than
3.5 l/min
min burner pressure
Flow <2.7 l/min
gas valve off
If burner on less than
3 min;
10 sec pump and fan
over-run
If burner on more than
3 min;
10 sec over-run
80 sec fan over run
10 sec pump over run
80 sec fan over run
Pump on
for
4 minutes

Worcester 28i RSF Specifications

General

Model	28i RSF
Output	28kW
Mounting	Wall-mounted
DHW Output	28kW
ERP Rating	A
Fuel Type	Natural Gas
Water Pressure	3 bar