tekmar 423 Universal Reset Module - Manual (Page 29)

29 of 36 © 2007 D 423 - 08/07
Setpoint Priority Override
Setpoint Priority Override applies to SETPOINT MODE 2
and MODE 4. To prevent the building from cooling off
too much or the possibility of a potential freeze up during
setpoint priority, the control limits the amount of time for
setpoint priority. As the outdoor air temperature becomes
colder, the length of time the control provides setpoint
priority is reduced. Once the allowed time for priority has
elapsed, the control overrides the setpoint priority and
resumes space heating.
Conditional Setpoint Priority
If the boiler supply temperature is maintained at or above
the required temperature during setpoint generation, this
indicates that the boiler has enough capacity for setpoint
and possibly heating as well. As long as the boiler target
temperature is maintained, setpoint and heating occur at
the same time.
Pump Operation Section K
Primary Pump
The primary pump is switched on in the following
situations:
•
• There is a Boiler Demand and that zone’s thermostat
has H1 Pump set to ON.
• • There is a Mix 1, Mix 2 or Mix 3 Demand.
•
• There is a DHW Demand and the control is set to DHW
Mode 3 or 4.
• • The control is completing a DHW Purge.
•
• There is a Setpoint Demand and the control is set to
Setpoint Mode 3 or Mode 4.
DHW Pump
The DHW Pump operates whenever there is a DHW Demand
and the control is not in DHW Priority Override.
Pump Exercising Section L
The system control will exercise all pumps, mixing valves and hydronic zones (zone valves and zone pumps) for 10 seconds
every three days to prevent seizure.