DHW METHODS HeatNet Control V3
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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.
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.