Dunkirk Helix VLT Vertical Laser Tube, Wall Hung Modulating Condensing Boiler - Manual (Page 2)

2
MULTIPLE BOILER GUIDE
1 - Multiple Boiler Operation
System Setup
• Boiler control can be applied for multiple boiler systems in cascade setup.
• System sensor input is available on low voltage terminal block to measure cascade system supply temperature.
• CH & DHW pump outputs are available on managing boiler.
• When CH supply temperature is calculated based on outdoor sensor, only one outdoor sensor is needed. Sensor is
connected to managing boiler and calculates CH setpoint for cascade system.
• In case of cascade in combination with domestic hot water tank DHW pump can be connected to pump output of
managing boiler control. Thermostat must be wired to managing boiler.
Cascade boiler pump connections
System confi guration for handling DHW store or central heating demand. All boilers handle either DHW storage
or CH heating demand at one time.
Figure 1 - Typical Multiple Boiler Piping
3/8"/10mm Open End
Wrench
DHW
Pump
CH/System
Pump 12"/305mm Maximum Separation
System
Temperature
Sensor
Size common piping
per maximum heat
capacity of entire
system
All internal
primary loop
ball valves
closed
Limit length
to 5' (1.6m)