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Monobloc Outdoor Unit
8.2.8.
Domestic Hot Water Priority
The DHW Priority function allows the end user to force the system into DHW mode irrespective of the space heating
demand and the current DHW schedule. The function acts as a DHW override function to generate DHW outside of
the DHW scheduled time periods.
The control is activated using a custom digital input (DI). The function of the DI must be set using the software
parameters ([P502] to [P505] depending on DI selected for the DHW Priority function.
When the status of the selected DI goes from CLOSED to OPEN (falling edge detection – pulse input) the DHW
Priority function is enabled and the system is available to produce DHW for the programmed duration ([P708]:DHW
Exception Time) regardless of any space heating / cooling demand and the current DHW schedule. The DHW
production is controlled using the standard DHW system control.
The DHW Priority function is ON when:
a. A pulse input signal is received from a custom DI (set up for the DHW Priority function AND the DHW
Exception timer is not "timed out"
The DHW Priority function is OFF when:
b. The DHW Exception timer has "timed out"
DHW Setpoint [P406]
∆T Stop [P722]
∆T Start [P721]
ON
DHW Scheduler
[P711] + [P712] +[P713]
OFF
ON
DHW Priority
DI-05: [P502]= 6
OFF
ON
DHW Exception timer
[P708] + [P209]
OFF
ON
DHW Operation
OFF
ON
Space Heating Mode
OFF
Control overview:
[1] The normal DHW schedule is OFF. At this point if there was a DHW demand then the system would not
change operating modes to produce DHW
[2] When there is a DHW demand and the normal DHW schedule is OFF the DHW Priority function can be used
to override the DHW scheduler. A pulse input is required from one of the custom DI's (set for DHW Priority).
When the status of the pulse input changes from CLOSED to OPEN (falling edge detection) then the DHW
Exception timer is started and the DHW Priority function is enabled
[3] During the DHW Priority period the system produces DHW using the standard DHW control. The system will
change to DHW production mode when:
DHW_TT < DHW_CTRLP [P406] - ∆T DHW Start [P721] AND DHW Exception timer ON
[1]
[2]
[3]
42
[4]
[5]
Service Manual
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