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106308-05 - 3/23
APEX Installation, Operating, & Service Instructions
Sequencer Master
(Boiler 1)
Boiler 2
Wiring locations:
Enable/Disable X
DHW Demand X
System pump X
DHW pump X
Boiler Pump X X
Sequencer Master Parameter Selections:
Sequencer Master Enabled
Indirect Water
Heater
“Boiler Piped”
Pump Parameter Selections:
System Pump =
Central Heat,
No Priority
Never
Boiler Pump =
Central Heat,
Off DHW Priority
Any
demand
DHW Pump = Boiler Piped IWH Never
Explanation:
Make sure indirect water heater and DHW pump are sized to maintain flow though boiler within limits shown in Table 6-3.
This piping arrangement does not allow both the Slave 1’s boiler and domestic hot water pump to run at the same time.
When call for Domestic Hot Water is received the DHW pump is turned on and the boiler pump is turned off. However, the
system pumps may run to satisfy a central heat demand that is being satisfied by a different slave. The central heat demand
is ignored by Slave 1 until the domestic hot water demand is ended. If domestic hot water priority is enabled and priority
protection time is exceeded the domestic hot water pump turns off to allow the boiler pump to run.
Multiple Boilers, Boiler Piped Indirect Water Heater
Multiple Boilers, Primary Piped Indirect Water Heater, Optional DHW Priority
Sequencer Master
(Boiler 1)
Boiler 2
Wiring locations:
Enable/Disable X
DHW Demand X
System pump X
DHW pump X
Boiler Pump X X
Sequencer Master Parameter Selections:
Sequencer Master Enabled
Indirect Water
Heater
“Primary Piped”
Pump Parameter Selections:
System Pump =
Central Heat,
Optional Priority
Never
Boiler Pump = Any demand
Any
demand
DHW Pump =
Primary Loop
Piped IWH
Never
Explanation:
This piping arrangement permits the system pump to run or not run when there is a domestic hot water call for heat.
Domestic hot water priority is optional. It is permissible for the domestic and system pumps to run at the same time. The
boiler pump must run for every call for heat.
10 Operation (continued)
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