Thermal Solutions APEX APX425C Installation, Operating And Service Instructions page 92

10
Operation
(continued)
Multiple Boilers, Boiler Piped Indirect Water Heater
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, Primary Piped Indirect Water Heater, Optional DHW Priority
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.
92
APEX Installation, Operating, & Service Instructions
Sequencer Master
Wiring locations:
Enable/Disable
DHW Demand
System pump
DHW pump
Boiler Pump
Sequencer Master Parameter Selections:
Sequencer Master
Indirect Water
"Boiler Piped"
Heater
Pump Parameter Selections:
System Pump =
Boiler Pump =
Off DHW Priority
DHW Pump = Boiler Piped IWH
Sequencer Master
Wiring locations:
Enable/Disable
DHW Demand
System pump
DHW pump
Boiler Pump
Sequencer Master Parameter Selections:
Sequencer Master
Indirect Water
Heater
Pump Parameter Selections:
System Pump =
Boiler Pump =
DHW Pump =
Boiler 2
(Boiler 1)
X
X
X
X
X X
Enabled
Central Heat,
Never
No Priority
Central Heat, Any
demand
Never
Boiler 2
(Boiler 1)
X
X
X
X
X X
Enabled
"Primary Piped"
Central Heat,
Never
Optional Priority
Any
Any demand
demand
Primary Loop
Never
Piped IWH
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