Worcester Greenstar Heatslave II External 12/18

230V on
DHW L
R
AND fascia
mounted
programmer
DHW ON
(if fitted)
NO DHW
ON
period on
programmer
AND/OR
0 Volts on
DHW LR
[203]
Appliance
Mains power
supply ON
3 way valve
to DHW
[203]
3 way valve
to DHW
[203]
NO DHW OR
Heatslave tank
DEMAND
[203]
Heatslave tank
sensor less than
tank setpoint
minus tank offset
DHW flow
2 l/min or greater
Pump OFF
(at tank temp peak)
[203]
Tank adaptive offset
adjusted
[203]
2 to 5.9 l/min DHW
flow
(low flow rate)
[201]
DHW
DEMAND
[201]
DHW flow
2 I/min or
greater
DHW
DEMAND
[201]
Blue light ON Tap
symbol on display
[201]
Pump
ON
[201]
DHW DEMAND END
(DHW flow less than
1.6 l/min)
[203]
Pump
OFF
[203]
Blue light OFF
No Tap symbol
on display
[203]
Pump remains ON until tank
temp peaks (scavenging heat from PHE)
[201]
Burner
OFF
[201]
Heatslave
TANK
DEMAND
[201]
Blue light ON Tap
symbol on display
[201]
Blue light ON
Tap symbol on display
[201]
Pump
ON
[201]
6 to 9.9 l/min DHW
flow
(medium flow rate)
[201]
10 l/min or greater
DHW flow
(high flow rate)
[201]
Pump
ON
[201]
Pump
ON
[201]
Pump
ON
[201]
DHW flow less than
1.6 l/min
DHW DE MAND END
[203]
Tank offset reduced
during medium flow
rate demand
(see chart)
Burner
ON
[201]
Burner ON: (IF PHE temp less
than tank setpoint minus tank offset)
[201]
Tank heated to tank
setpoint - tank
adaptive offset
[201]
Burner OFF if tank
sensor greater than
tank setpoint + 1°C
[201]
Less than 9.5 l/min
DHW flow
[201]
Burner ON if tank
sensor greater than
tank setpoint
[201]
Burner
OFF
[201]
Less than
5.5 l/m
DHW flow
[201]
Normal tank offset
applied
(see chart)
[201]
Blue light OFF No
Tap symbol on display
[203]
Blue light OFF No
Tap symbol on display
[203]
FAULT FINDING & DIAGNOSIS
DHW FUNCTION CHART
FAULT FINDING & DIAGNOSIS
DHW FUNCTION CHART
INSTALLATION & SERVICING INSTRUCTIONS FOR GREENSTAR HEATSLAVE II EXTERNAL 12/18-18/25-25/32 6 720 805 210-01
57
FAU LT FI NDI NG
& DIAGNOSIS
Demand conditions:
Comfort setting
Eco setting
With no other demands
8
10
With medium DHW flow rate
4 8
With DHW burn
4 8
With CH burn
6 6
Tank offset chart
NB: The demands run in parallel therefore the tank can demand during a DHW demand and will reheat the tank, (e.g. during a low
flow rate DHW demand). Likewise a greater than 10 l/min DHW demand during the tank scavenge period will fire the burner to
satisfy the demand.
If DHW is OFF on the programmer and/or there is 0 volts on DHW LR then the appliance will still supply DHW using the heat stored
in the tank, but it will not reheat the tank, therefore the amount of water available is limited but is adequate for washing up, filling
basins etc.
The 3WV rests in DHW position unless there is a current CH demand with no DHW or tank demand.
DHW and tank demands override any CH demand, if the burner is ON for CH and a DHW/tank demand starts that requires a burn,
the burner will remain ON whilst the demand transfers over to DHW.
NB: Numbers in square brackets are the cause code of the current appliance operation, visible in the service menu slot 1 (i1),
Key:
Tank Heatslave internal thermal store.
3WV 3 way valve (diverter valve).
PHE Primary heat exchanger.
Tank setpoint The target temperature for the tank = the DHW fascia control knob setting.
Tank offset The amount the tank can cool before a tank reheat demand is triggered.
Tank adaptive offset The learnt value for switching the burner off so that the tank peak temp after scavenging heat from
the PHE after burner shut down = tank setpoint.
The appliance will adjust this value during operation so that the tank setpoint is achieved
automatically (this will take a few tank reheat cycles), after any burner output changes or if the burner
output drops between services.