SYX66x Commissioning Guide
V1.10.3 300117
Page 47 of 61
a VT Valve may need to be installed. Do not permit a high primary flow temperatures into heating areas serving
young children or old people unless adequate measures to protect against surface contact is made. This controller
is not responsible for the settings left for safe and continued operation. If in doubt ask. The Primary flow set point
can be adjusted but this will affect recovery times and also the available tank temperatures.
This also assumes that the HWS system has its own pumps servicing the boilers with adequate overrun and
interlocks.
On Valve
– If there is a VT Valve being used then the valve can be closed to afford full heat to the HWS Cylinder.
The Heating Pump is not affected. If after 30 minutes of HWS and VT heating the HWS Tank is not fully satisfied
then the VT Valve will be closed. It will close for a maximum of 30 minutes or until the HWS is satisfied.
The On Pump and On Valve time cycles will repeat to allow heat into the rooms and afford priority until the HWS or
Heating are no longer in demand.
HWS Priority Modes only operate when the Mode selection is in Auto or Continuous.
During priority active periods the Optimiser Adaption is inhibited and the indicator lamp will illuminate respectfully of
Valve or Pump Priority being active.
11.2
Values Page
Control
– HWS Primary Set point – If the HWS is linked to the boilers then when the HWS is running this set point
will be issued to the boilers. If the HWS Demand function is also selected on the Auxiliary input, then the Auxiliary
input connection is typically connected to a volt free status of the HWS control stat or HWS valve actuator confirming
that it is open and requiring heat from the boilers. When this input closes only then will the boilers be requested to
run to heat the HWS system.
Note: YPLAN Mode required the Boilers to be linked and the Aux input to be configured as HWS Demand.
