SYX66x Commissioning Guide
V1.10.3 300117
Page 46 of 61
11.
HWS Menu Pages
11.1
Switch page
HWS Override
– This allows the user to override the HWS System independently of the heating system. The HWS
Times can be overridden On or Off. This will be the case until the HWS is set back to Auto. Setting the controller to
Auto will allow it to follow the Time Schedule and extension overrides.
HWS Primary Set point
– If the HWS is dependent on the boilers for the supply of Primary water then the boiler
linked option must be set. When the boilers are running they require a set point to meet. The HWS Primary set point
value should be entered to ensure the HWS is heated appropriately. Please note that if there is no VT Valve fitted
then this flow temperature will also be distributed to the Heating Circuit.
If the HWS Heat Demand (Control Stat or Valve Auxiliary Switch) is monitored on Pin 10 then you may also consider
the use of HWS Priority.
The controller has the option to enable a HWS priority feature and this is given to help with undersized boilers when
the boilers are linked to the HWS as well as for heating the building. For example if the HWS Cylinder is struggling
to heat up to the required temperature in an adequate time (e.g. 30 minutes) then the heating can be reduced to
afford the HWS a faster recovery time. This is called HWS Priority.
HWS Priority can be enabled in two ways
1. Heating Pump Control
2. VT Valve Control
Note: Only when the boilers are linked to the HWS and HWS Heat Demand Control Input is selected and is asking
for heat (closed contact)
No Priority
– There is no HWS Priority Required. Default Setting
On Pump
– If there is no VT Valve installed then the highest set point between the VT and HWS Primary
Temperature will be issued to the building from the boilers when the pump is running (standard operation). This
however could cause under or overheating of the building when long HWS times are in effect. This could be
inefficient and wastes energy as we may not need such a high flow temperature in the building areas. The On Pump
mode will disable the pump when the HWS takes longer than 30 minutes to become satisfied. The pump will return
to Auto when the HWS is satisfied. The maximum time the heating pump will be turned off is for is 30 minutes or
until the HWS is satisfied.
Note: If the heating system is not rated for the Primary Flow Set point then a system design review is needed e.g.
