RBI FUTERA XLF Series, Control Manual

Page: 34 / 128

DHW METHODS HeatNet Control V3
Page 34
DHW Method 2: Failsafe Combination DHW and Space Heating with a MASTER
Boiler and MEMBER Boilers Utilizing Valves (MASTER Type: Combination)
Figure 29 In this example the MASTER is not a DHW boiler.
Member 2
Cold Water
Makeup
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Backflow
Prevention
Pressure
Reducing
Ball Valve
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Member 3 Master
Domestic Hot
Water
Supply
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WM
Water Meter
3-Way
Valve
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Heating
Only
Combination
Failsafe
Heating
Combination
Failsafe
DHW
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Outdoor Air Sensor
System Return
System Header Sensor
System Return Sensor
System Pump
MIN 3X PIPE DIAMETERS
MAX 10X PIPE DIAMETERS
BETWEEN CENTERS
System Supply
DH
W
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3-Way
Valve
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HeatNet
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HeatNet HeatNet
DHW METHOD 2: Failsafe Combination DHW and Space Heating using a MASTER Boiler and MEMBER boilers with
valves
In this method the MASTER simultaneously controls both space heating and DHW heating. The MASTER is piped to only
service space heating, and both MEMBERs are piped to service space heating and DHW heating. The MASTER’s
Heat Demand
input enables space heating by energizing the system pump and maintaining the Heating Setpoint at the System Header Sensor.
The MASTER’s
OR OVR input enables the DHW heating, by maintaining the DHW Setpoint at the DHW Sensor located in the
DHW tank.
Boilers are staged to meet both the Space Heating Setpoint, and the DHW Setpoint based on their runtime. When a boiler is fired
to service a space heating demand it will enable its local pump, and when a boiler is fired to service a DHW demand it will enable
its local pump and enable its DHW valve to divert water to the tank. The MASTER modulates the boilers in order to maintain the
setpoints.
This method allows for a MEMBER boiler to provide Failsafe mechanisms in the event the MASTER fails and stops
communicating to the MEMBERs. MEMBER 2 is configured to provide failsafe space heating, and MEMBER 3 is configured to
provide both failsafe space heating and failsafe DHW heating.