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Mode 3 (Type H Units Only) - Hydronic Heating with Indirect DHW on the Water Heater Loop
Refer to
Fig 30 and 31
This mode selection is for hydronic heating systems with single or multiple water heaters (Maximum 4
water heaters) in primary/secondary piping configuration with or without Outdoor Air Reset (S4) with
indirect DHW on the water heater loop (with priority).
The system temperature is controlled by the Supply sensor (S3) whenever the indirect call for heat is
not active.
The DHW Supply sensor (S5) determines the indirect tank set point. During an indirect call for heat the
water heater firing rate is determined by the water temperature at the Indirect Supply Sensor (S6) and
the Target Max setting when using the Indirect DHW sensor (S5).
The Water Heater Pump (P1) runs during all heat calls regardless of priority.
The Indirect DHW Pump (P3) runs during an indirect call for heat with no "off" delay.
The Water Heater Pump (P1) and System Pump (P2) delay "off" as user defined in the ADJUST menu.
The System Pump (P2) runs whenever the system is enabled for heating and the outdoor air
temperature is lower than the WWSD temperature setting (if utilized) unless an indirect call for heat is
present.
NOTE: A Tank Aquastat can be used in lieu of the Indirect DHW Sensor (S5). See Operational Settings
below for additional details.
Fig. 30: MODE 3 - Single Water Heater with Indirect DHW on Water Heater Loop
on page 62.
62
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