CONTROL METHODS
HeatNet Control V3 3.x
Page 38
This method requires a 10k thermistor connected to the
DHW Sensor input of a DHW MASTER, or a stand-alone
boiler, and a DHW tank. This method does not use a
HEADER sensor. The DHW temperature is maintained by
the space heating PID for backwards compatibility. With
this method the OR OVR input does not function as a DHW
enable and is not used. The Heat Demand input is used to
enable/disable DHW heating operations.
The System pump is enabled on the MASTER as long as the
Heat Demand input is closed. The selected network boiler’s
Local pump is engaged when there is a call for DHW
heating by the MASTER. This allows for a DHW
loop/buffer and A DHW tank that can be heated using the
MASTER’s DHW pump (Reverse/Return only) or each
boiler’s Local Pump/Valve supplying this loop/buffer.
DHW Page 1
DHW Page 2
Boilers are started as long as the tank’s water temperature is
below the (DHW SETPOINT – LOWER BAND). The first
boiler is started immediately. The next boiler(s) is started
after the ADD BOILER DELAY time expires. Boilers are
not added when the temperature is above the (DHW
SETPOINT – LOWER BAND) and below the UPPER
BAND. Once the UPPER BAND is exceeded, boilers will
shut off based on the SHED BOILER DELAY TIME.
Setting up this method is done via the menu in:
SETTINGS: DOMESTIC HOT WATER.
Connect a
10k thermistor from the DHW tank’s sensor
well to J10B terminals on the DHW MASTER, or
stand-alone boiler. Wire a pump or valve from the Local
pump of each DHW boiler.
A DHW call is when the DHW temperature is
below the (DHW SETPOINT – LOWER BAND)
or when the DHW temperature is below the (DHW
SE UPPER BAND) and boilers are
firing.
The Masters System pump (Normally Open) will
always be enabled as long as the Heat Demand
input is closed.
The MASTER’s DHW pump (Normally Open)
relay contacts will close during a DHW call. Once
the call has ended, the last DHW boiler stops firing,
and the programmed post-purge time has expired,
the MASTER’S DHW contacts will open. In this
application the Masters DHW pump can be used
globally.
After a DHW call ends the Local pump will remain
on during a post purge pump cycle until the post
purge timer expires.
DHW Only Method 1 Set Up:
1.
Enter the
DOMESTIC HOT WATER
menu on
the MASTER boiler. In the
BOILER MODE
selection, enter
DHW ONLY
. The MASTER uses
this method as a DHW system much like a space
heating system.
MEMBER boilers may set the
BOILER MODE
to
LOCAL and go offline to perform secondary DHW
heating, but the MASTER setting must be set to
AUTO/OFF
.
Setting the
BOILER MODE
to
Combination
using
this method may cause erratic operation and the DHW
pump to not be enabled.
2.
Change the
DHW SETPOINT
to the desired target
temperature of the water in the tank. Once the control
determines there is a call for DHW, the DHW
SETPOINT is loaded, and the MASTER boiler will
target the setpoint.