Page 25
Cascading the FT Series ‘Heating Only’ Boiler
The cascade system can be activated by a dry contact thermostat (T/T connections on Leader boiler) or by an
external 0-10V signal (on the Leader boiler).
In order for the space heating portion of the system to operate properly, the thermostat, 0-10V signal, and/or
outdoor sensor MUST be connected to the Leader boiler only. The follower boilers will run based on Leader
boiler’s controls.
Note: The temperature sensor for the indirect water heater must be wired directly to the boiler that is piped
to the indirect water heater. If multiple boilers are needed use an aquastat and wire it in parallel with “DHW
Temp Sensor” contacts on the boilers to be used for DHW. Ensure the DHW circulator is wired to the “DHW
Pump” contacts on a boiler that is piped to the indirect water heater. If there is an active call for Heat and a
simultaneous call for DHW, the boiler(s) receiving the DHW call will prioritize the DHW call while the remaining
boilers in the cascade will continue to attempt to satisfy the call for Heat.
Reference the FT Series Wall-Mounted or Floor Standing Heating Only Installation and Operation Manual
(Doc# 1483 or Doc# 1510) to set the Leader’s boiler temperature set point based on an outdoor sensor, 0-10
Volt signal or a fixed temperature setpoint.
In case one desires to shut down certain space heating pumps on a call for DHW, the L leg of the CH pump
terminals on the Leader boiler can be used to temporarily interrupt a multi-zone relay panel during priority call
for DHW. Please consult the relay panel manufacturer for detailed instructions.
FT1861 : FT Series Cascade Communication Cables.
Install per local codes and requirements.
