CONTROL METHODS HeatNet Control V3
Page 45
This method is for controlling DHW utilizing a tank
thermostat connected to a Master boiler. This method
requires a thermostat input to the OR OVR. When the
thermostat contact closes across the input OR OVR
(J12A .7 & .8), the control will sense this closure and
override the space heating setpoint with the DHW
setpoint. SETTINGS: DISTRIBUTED CONTROL:
MASTER TYPE: AUTO.
This method is for backwards compatibility.
In this mode, the boiler will fire to the DHW
setpoint. The settings for space heating will be used
except for the addition of controlling the DHW
pump/valve by the Master boiler.
1. Wire the dry contact from the thermostat on the
tank to the input on J12A terminal 7 & 8 (OR
OVR). Also, at this time wire any pump or
valve from the DHW Pump relay (normally
open) contact (J13 terminals 16, 17, & 18) of
the Master to control flow of the heating water
into the tank’s coil.
2. Enter the DOMESTIC HOT WATER
MENU. Go to BOILER MODE and enter
OFF/AUTO.
3. DHW SETPOINT The setpoint should reflect the
temperature desired in the heating loop when a tank is
calling for DHW heat.
4. LOWER BAND This is not used.
5. UPPER BAND This is not used.
6. PUMP PRIORITY Setting this value to YES will
turn OFF the system pump when the DHW setpoint
override mode is active. Setting this value to NO
leaves the system pump on. This active period
includes the post purge of the DHW pump/valve.
7. Select the menu item POST PURGE. This is the time
that the DHW pump relay remains energized after the
DHW thermostat has been satisfied. Once the tank
has opened its thermostat, the system/local setpoint
will be reloaded and the post purge time will begin.
8. Select the menu item: LOCAL PUMP OFF: When a
DHW heating cycle begins, what to do with the local
pump/valve is determined:
NO The local pump/valve will remain running during
DHW heating.
YES The local pump will shut off with a delay
determined by LOCAL DELAY: seconds. This
allows the DHW pump/valve to prove before
shutting off the local pump.
Piping of the system will determine which setting
to use.
9. Select the menu item: PURGE TO. After a DHW
cycle completes, the pump/valve can be selected to
either purge to the TANK, or to the SPACE for the
duration of the post purge time. This selection can use
the space to dump the heat from the boiler and not
overheat the DHW tank/load.
10. Set the HYB SENSOR = OFF. This sensor is
selectable for Method 5A only.
Follow the same steps as used to program DHW
Heating using a Header Sensor INPUT. USE
SENSOR, select NO.
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