OPTIONAL FEATURES
HeatNet Control V3 3.x
Page 67
Figure 48
Outdoor reset curve, typical
The above chart shows how the water temperature setpoint
changes with the Outside air temperature. The four values of
180, 10 and 140, 70 are the default values:
WATER TEMP
LOW OA TEMP
180 °F
10 °F
Water temp @
outside air temp
WATER TEMP
HIGH OA TEMP
140 °F
70 °F
Water temp @
outside air temp
WWS Setpoint
72 °F
Outside air temperature
where Warm Weather
Shutdown occurs
WARM WEATHER SD=ON
If set to ON here
The chart (Figure 48) depicts what the water temperature
setpoint will equal with a corresponding outside air
temperature. At an outside temperature of 10F and below, the
water temperature setpoint will be limited to 180F. With an
outdoor temperature of 70F and above, the water temperature
will be limited to 140F. The water temperature setpoint will
track along the charts plotted line with corresponding outside
temperatures.
The OR OVR (Outdoor Reset Override) input on J12A can be
used to override this Outside Air Setpoint and maintain the
water setpoint at the LOCAL or SYSTEM SETPOINT value
when a contact is closed across this input. This can be used as
a Domestic Hot Water demand input.
Another function of the OUTDOOR RESET is the
Winter/Summer mode ((W)arm (W)eather (S)hutdown). With
the WWS SETPOINT set to 72F and WARM WEATHER
SHUTDOWN set to ON, the boiler/system will enter summer
shutdown when the Outside Air temperature rises above 72F.
While in this state, the OR OVR input on J12A can be used to
bring the boiler/system on to maintain the water setpoint at
the LOCAL or SYSTEM SETPOINT value.
During WWS operation, the System pump will not be enabled
just the Local pump unless the SETTINGS: SYSTEM PUMP:
OVERRIDE ENABLED IN WARM WEATHER
SHUTDOWN is set to ON. This is the System Pump
Priority mode. When SETTINGS: SYSTEM PUMP:
OVERRIDE ENABLED IN WARM WEATHER
SHUTDOWN is set to OFF, the system pump will not come
on while in WWS with the OR OVR override input closed.
Sensors
The H-Net control supports a standard 10K thermistor (Type
ACI/10K-CP). These sensors can be calibrated to the control
by entering the sensor menu and placing a precision 10k
resistor on an input.
Sensors should be wired using a twisted
shielded pair cable of 18-22 AWG wire.
Immersion sensors must have wells.
There is also a provision to use a 1K platinum sensor for the
stack temperature. The 10k thermistor is limited to a usable
range of 270F, and the 1k platinum sensor to upwards of
1000F. The S5 DIP switch is used to configure one or the
other.
Stack Temperature
The version 3 control also supports an optional 1k platinum
stack sensor. If the Stack Sensor is present, a warning will
occur at 325F and greater. During the Warning condition, for
every degree F over the warning temperature of 325F, the
boiler’s input will be limited by 4% until the boiler is running
at low fire. If the SETTINGS: HEAT EXCHANGER:
ALARM TYPE: is set to” FAULT” the boiler will halt and
the Alarm relay will close when the Stack temperature
exceeds 350F. The boiler will then be allowed to restart when
the Stack temperature drops below 325F.
130
140
150
160
170
180
190
10
70
Wate
r Te
m
p
Outside Temp
WATER TEMPERATURE SETPOINT