BLD2024-1015_Other_8.5.2024_11.41.09_AM_4421096TFTN 085-399 Installation and Operation Manual
11.0 CASCADE INSTALLATION
Multiple Boiler Applications
The TFTN controller has the internal capacity to stage/lead-lag up to eight (8) TFTN boilers connected in cascade, without
the need for external controls. Each boiler in cascade is connected to the BUS circuit, which allows the "Manager" boiler to
communicate with and control the "Follower Boilers". Use the instructions detailed in the section to complete the
installation and setup of the cascade, taking care to follow the instructions in the order presented.
11.1 General Installation Instructions
Before performing the Setup Procedure, and before turning the power on or connecting the BUS terminals to each boiler,
proceed with the following General Installation Instructions:
1. Plumbing— install as many as 8 TFTN boilers in parallel in a primary/secondary plumbing configuration as illustrated in
Figure 11-1. Size common piping as per Table 11-1.
2. Boiler Pump — each boiler must have its own circulator which is controlled by its respective BLR PUMP output (or
AUX1/2 PUMP output in the case the boiler is connected to an Upstream IWH); see Figure 11-1. The Boiler Pump must
be sized according to Table 10-3.
3. System Pump (if applicable) — wire to the AUX2 PUMP output of the boiler set as Manager; see Figure 11-1.
4. DHW Pump — Downstream IWH (if applicable) — wire to the DHW PUMP output of the boiler that will be set as
Manager; see Figure 11-1.
5. DHW Pump — Upstream IWH (if applicable) — wire to the DHW PUMP output of the boiler that the Upstream IWH is
piped to; see Figure 11-1.
NOTE: The Manager boiler cannot be configured to heat an Upstream IWH if the cascade system includes a
Downstream IWH. When a Downstream IWH is present, Upstream IWHs may only be connected to the
Follower Boilers.
6. System Sensor (mandatory) — install a system sensor (NTI P/N: 84010) on the common outlet (supply) pipe feeding
the heating system and wire it to the AUX1 NTC input of the boiler that will be set as Manager; see Figure 11-1.
NOTE: A system sensor is needed for the cascade system to function properly. Failure to connect the system sensor
and properly configure the AUX1 NTC input will result in "Blocking Error 115" (Common flow sensor error), and
the cascade will function using an average of the outlet temperature from each boiler in cascade.
7. Outdoor Sensor (optional) — wire the outdoor sensor to the OD NTC input of the boiler that will be set as Manager;
see Figure 11-1.
8. Downstream IWH DHW Tank Sensor or Aquastat (if applicable) — wire to the DHW SWITCH/NTC input of the boiler
that will be set as Manager; see Figure 11-1.
9. Upstream IWH DHW Tank Sensor or Aquastat (if applicable) — wire to the DHW SWITCH/NTC input of the boiler that
the Upstream IWH is piped to; see Figure 11-1
NOTE: The Manager boiler cannot be configured to heat an Upstream IWH if the cascade system includes a
Downstream IWH. When a Downstream IWH is present, Upstream IWHs may only be connected to the
Follower Boilers.
10. DHW Recirc Sensor (if applicable) — connect to the AUX2 NTC input of the boiler that will be set as Manager.
11. Buffer Tank Sensor (if applicable) — connect to the AUX2 NTC input of the boiler that will be set as Manager.
NOTE: The AUX2 NTC input can be used to connect either a DHW Recirc sensor or a Buffer Tank sensor, not both.
Cascade configurations are not compatible with applications requiring both DHW recirculation temperature
control and buffer tank temperature control.
12. CH Thermostat Inputs and Zone Outputs — connect up -to six (6) thermostat inputs to T-STAT #1/2/3 at two (2) of the
TFTN boilers in cascade. Connect the respective zone loads (pumps or valves) to the same boiler's ZONE OUTPUTS
(ZONE 1/ZONE 2/ZONE 3).
NOTE: Each TFTN boiler is equipped with a zone controller capable of operating 3 zones, but only two of the zone
controllers can remain connected on the BUS when cascading (for a total of 6 zones), the others need to be
disconnected; see Figure 11-2.
NOTE: Zones 1, 2 and 3 at the boiler whose zone controller have the dipswitches set to off, become zones 4, 5 and 6
respectfully; see Figure 11-2. The examples in Figure 11-1 assume that the Follower boiler's zone control
dipswitches are set to off, while the Manager boiler's dip switches remained in the factory on position.
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