Laars FT Series User manual

Cascade Instructions Document 1349C
H2384200C
WARNING
If the information in this manual is not
followed exactly, a re or explosion may
result causing property damage, personal
injury or loss of life.
Do not store or use gasoline or other
ammable vapors and liquids in the vicinity of
this or any other appliance.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not
use any phone in your building.
• Immediately call your gas supplier from a
nearby phone. Follow the gas supplier's
instructions.
• If you cannot reach your gas supplier, call
the re department.
Installation and service must be performed
by a qualied installer, service agency, or gas
supplier.
FOR YOUR SAFETY: This product must be installed and serviced by a professional service technician,
qualied in hot water boiler and heater installation and maintenance. Improper installation and/or operation
could create carbon monoxide gas in ue gases which could cause serious injury, property damage, or
death. Improper installation and/or operation will void the warranty.
AVERTISSEMENT
Assurez-vous de bien suivres les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion
ou pour éviter tout dommage matériel, toute
blessure ou la mort.
Ne pas entreposer ni utiliser d’essence ou ni
d’autres vapeurs ou liquides inammables dans
le à proximité de cet appareil ou de tout autre
appareil.
QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE
GAZ:
• Ne pas tenter d’allumer d’appareils.
• Ne touchez à aucun interrupteur. Ne pas vous servir
des téléphones dans le bâtiment où vous vous
trovez.
• Appelez immédiatement votre fournisseur de
gaz depuis un voisin. Suivez les instructions
du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de
gaz, appelez le sservice des incendies.
L’installation et l’entretien doivent être assurés par
un installateur ou un service d’entretien qualié
ou par le fournisseur de gaz.
Cascading the
Floor Standing and Wall-Mounted
Modulating Condensing Gas
Heating Only Boilers
FT SERIES
Floor Models: B/LFTHF199
Wall-Mounted Models: B/MFTHW 100, 140, 199
• Natural Gas (NG)
Factory Conguration
• Propane Gas (LP)
Field-Convertible

Page 2
Table of Contents
SECTION 1 General Information. .........................................3
1.A General Plumbing Connection Guidelines ................................. 3
1.B Pipe Sizing for system and common supply
& return headers in Cascade Systems ....................................... 3
1.C Product Flow Paths and Characteristics .................................... 4
1.C.1 Floor Standing CH Circulation .................................................. 4
1.C.2 Wall-Mounted CH Circulation ................................................... 5
1.D High Voltage and Low Voltage Terminals
(wall and oor models) ............................................................... 5
1.E Miscellaneous Wiring .................................................................. 6
SECTION 2 Piping and Wiring Diagrams. ...........................8
2.A Cascade FT Floor Heating Only Boilers Piping
and Wiring Diagrams .................................................................. 8
2.B Cascade FT Wall-Mounted Heating Only Boilers Piping ......... 18
SECTION 3 Cascade Communications
(the cascade cable)..........................................22
3.A Cascade Kit Content and Instructions ...................................... 22
3.B Wiring Connections for Cascade .............................................. 22
SECTION 4 The Control Display..........................................26
4.A The Control Display ................................................................... 26
4.B The LCD ................................................................................... 27
SECTION 5 Cascade Programming....................................28
5.A Programming a Cascade System ............................................ 28
5.B The Cascade CH Function for Set Point Operation ................. 29
5.C Outdoor Reset Operation .......................................................... 30
5.D Domestic Hot Water ‘Storage Mode’ for Cascade System. .... 30
5.E Cascade System Error Codes .................................................. 32

Page 3
Cascading the FT Series ‘Heating Only’ Boiler
WARNING
Do not use FT Series units on common vents. Each unit must have its own supply and exhaust vents.
SECTION 1 General Information.
1.A General Plumbing Connection Guidelines
• Pipe material must be suitable to meet local codes and industry standards.
• The pipe must be cleaned and without blemish before any connections are made.
• Do not apply a torch within 12˝ of the bottom connections of the boiler. Doing so could damage the
boiler. Such damages ARE NOT covered by product warranty.
• Isolation (shutoff valves) should be used to ease future service.
• All piping should be insulated.
• Pump speeds in Table 1 refer to the internal boiler pump.
Multiple FT Series boilers can be connected via a cascade communication cable to create a bank
of boilers that work in tandem. Up to 20 boilers can be controlled by a “Leader” FT Series boiler
with the others acting as “Followers”. All cascaded boilers must be the same model and size.
1.B Pipe Sizing for system and common supply & return headers in Cascade Systems
Use piping diameters as per Tables 1 - 3 based on your maximum design delta T. Non-adherence to these sizing guidelines
may result in premature boiler failure and resulting problems are NOT covered by product warranty.
CAUTION
Use both thread tape and pipe dope to connect to the 1¼˝ or 1½" CH supply and return.
Notes: For FT Floor boilers, use 1-1/4" near boiler piping with a combined equivalent length not to
exceed 15 ft to the supply & return headers. Use 1-1/2" piping for longer runs.
Refer to page 8 of the FT Floor Installation and Operating Manual to set the internal valves as
follows for cascade operation: V1 and V3: closed,V2 open. (See next page)
An optional purge station is not needed for FT Floor models if the system piping is
above the boilers.
FT Piping Manifolds should NOT be utilized in wall-mounted multi-boiler cascade systems.
Table 1: Common Pipe Sizing for ∆T= 25 F (Speed 3 - default)
Model/# of units 1 2 3 4
5678
100 1" 1-1/2" 2 2 2-1/2" 2-1/2" 3 3
140 1-1/4" 2 2 2-1/2" 2-1/2" 3 3 4
199 1-1/4" 2 2-1/2" 3
3444
Table 2: Common Pipe Sizing for ∆T= 35 F (Speed 2)
Model/# of units 1 2 3 4
5678
100 1" 1-1/4" 1-1/2" 2 2 2 2-1/2" 2-1/2"
140 1" 1-1/2" 2 2 2-1/2" 2-1/2" 2-1/2" 3"
199 1-1/4" 2 2 2-1/2" 2-1/2" 3 3 4"
Table 3: Common Pipe Sizing for ∆T= 45F (Speed 1)
Model/# of units 1 2 3 4
5678
100 3/4" 1" 1-1/4" 1-1/2"
2222
140 1" 1-1/4" 1-1/2" 2 2 2 2-1/2" 2-1/2"
199 1" 1-1/2" 2 2 2-1/2" 2-1/2" 3 3

Page 4
R 0-10V W
(+) INPUT (-)
LWC
O/ST/T
DHW
TEMP.
SENSOR
DHW PUMP
L N G L N G
CH PUMP CASCADE
SYSTEM
SENSOR
Line Voltage Terminals
Line Voltage Terminals
Low Voltage Terminals
High and Low Voltage Terminals, Floor VS Wall.
R 0-10V W
(+) INPUT (-)
LWC
O/ST/T
AC24V
OUTPUT
DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMPL N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC
L-T/T
CASCADE
SYSTEM
SENSOR
Low Voltage TerminalsLow Voltage Terminals
1.C Product Flow Paths and Characteristics
Factory default valve position:
V1 and V3 open, V2 closed (single boiler).
For cascade operation with boiler pump:
Close V1 and V3. Open V2.
The oor model FT has these additional ----------------- voltage connections / functionalities
CH Supply
CH Return
Combustion Air Vent
GAS INPUT
V3
V1
The oor standing models have a built in low
loss header.
The boiler circulation pump circulates the CH water
in the boilers contained loop from heat exchanger
to the low loss header (LLH) and back. The
heating system pump or individual zone pumps
are required to pull heated water from CH supply
connection and return water to the CH return
connection.
Max Amp draw per pump = 1.6 Amps.
1.C.1 Floor Standing CH Circulation
Boiler
Circulation
Pump
V2
Figure 1. Floor model CH circulation
with LLH.

Page 5
Cascading the FT Series ‘Heating Only’ Boiler
R 0-10V W
(+) INPUT (-)
LWC
O/ST/T
DHW
TEMP.
SENSOR
DHW PUMP
L N G L N G
CH PUMP CASCADE
SYSTEM
SENSOR
Line Voltage Terminals
Line Voltage Terminals
Low Voltage Terminals
High and Low Voltage Terminals, Floor VS Wall.
R 0-10V W
(+) INPUT (-)
LWC
O/ST/T
AC24V
OUTPUT
DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMPL N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC
L-T/T
CASCADE
SYSTEM
SENSOR
Low Voltage TerminalsLow Voltage Terminals
The oor model FT has these additional ----------------- voltage connections / functionalities
The wall-mounted models do NOT have a built-in low loss header.
The boiler circulation pump circulates the CH water out the common
header up to 15’ of equivalent pipe at 1.5” diameter pipe.
Max Amp draw per pump = 1.6 Amps.
1.C.2 Wall-Mounted CH Circulation
1.D High Voltage and Low Voltage Terminals
Figure 2. Wall-Mounted CH circulation
Figure 3. Field Connections for WALL models
Figure 4. Field Connections for FLOOR models
CH Supply
Boiler
Circulation
Pump
CH Return
Combustion Air Vent
GAS INPUT
CH Supply CH Return
Gas Input
Combustion Air Vent
NOTE: The terminal blocks are NOT the same on the
oorstanding VS the wall-mounted models!
WALL MODELS
FLOOR MODELS

Page 6
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMP
Outdoor Sensor (18 Gauge Wire)
L N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Line Voltage Terminals Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
(14 Gauge
Wire)
(14 Gauge
Wire) (14 Gauge
Wire)
(14 Gauge
Wire)
External Remote TACO LWCO and High Limit Wiring Diagram, Combi.
System
Pump DHW
Pump
L-T/T
Pump
DHW Temp Sensors or Aquastat (18 Gauge Wire)
Thermostat or Endswitch (18 Gauge Wire)
TACO LTR STD Wire Harness
Hydrolevel harness
Green
White
Red
Yellow
Yellow
TACO LTR0243T-1 Low Water Cut-Off
Hydrolevel SAFGARD Model 1100, Low Water Cut-Off
Thermostat or Endswitch (18 Gauge Wire)
OR
7070
Floor Model Boiler 1 (Lead)
1.E Miscellaneous Wiring
R 0-10V W (+) INPUT (-)
LWC
O/ST/T
DHW
TEMP.
SENSOR
DHW PUMP
L N G L N G
CH PUMP CASCADE
SYSTEM
SENSOR
Line Voltage Terminals
Line Voltage Terminals
Low Voltage Terminals
High and Low Voltage Terminals, Floor VS Wall.
R 0-10V W (+) INPUT (-)
LWC
O/ST/T
AC24V
OUTPUT
DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMPL N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Low Voltage TerminalsLow Voltage Terminals
WALL MODELS FLOOR MODELS
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! A step-down transformer (120V to 24V) will be required on a Wall model for 24 volt output.
Figure 5. Taco LTR0243T-1 -OR- SAFGard 1100
External LWCO

Page 7
Cascading the FT Series ‘Heating Only’ Boiler
R 0-10V W (+) INPUT (-)
LWC
O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMP
Outdoor Sensor (18 Gauge Wire)
L N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Line Voltage Terminals Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
(14 Gauge
Wire)
External Remote TACO LWCO and High Limit Wiring Diagram, Combi.
Hydrolevel Company SafGard Model 500 (24VAC) Low Water Cut-Off
2 1 P1 P2 A
(18 Gauge
Wire)
(14 Gauge
Wire) (14 Gauge
Wire)
(14 Gauge
Wire)
System
Pump DHW
Pump
L-T/T
Pump
DHW Temp Sensors or Aquastat (18 Gauge Wire)
Thermostat or Endswitch (18 Gauge Wire)
Thermostat or Endswitch (18 Gauge Wire)
7070
Boiler 1 (Lead)
R 0-10V W (+) INPUT (-)
LWC
O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMP
Outdoor Sensor (18 Gauge Wire)
L N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Line Voltage Terminals
Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
(14 Gauge
Wire)
(18 Gauge
Wire)
External Remote TACO LWCO and High Limit Wiring Diagram, Combi.
Hydrolevel Company SafGard Model 550 (120VAC) Low Water Cut-Off
2 1 P1 P2 A
(14 Gauge
Wire) (14 Gauge
Wire)
(14 Gauge
Wire)
System
Pump DHW
Pump
L-T/T
Pump 70
70
DHW Temp Sensors or Aquastat (18 Gauge Wire)
Thermostat or Endswitch (18 Gauge Wire)
Thermostat or Endswitch (18 Gauge Wire)
Floor Model Boiler 1 (Lead)
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! A step-down transformer (120V to 24V) will be required on a Wall model for 24 volt output.
Figure 6. SAFGard 500
External LWCO
Figure 7. SAFGard 550
External LWCO

Page 8
See Section 1.B on page 3 for common pipe sizes for system and return/supply headers for different system Delta T’s. See SECTION 3 on page 22 for cascade kit details. See Section 1.C on page 4 for reference to adjust the internal LLH valves (V-1, V-2, V-3) to their proper positions PRIOR to boiler installation.
WARNING: This drawing shows suggested piping conguration and valving. Check with local codes and ordinances for additional requirements.
SECTION 2 Piping and Wiring Diagrams
2.A Cascade FT Floor Heating Only Boilers Piping and Wiring Diagrams
Figure 8. Two FT oor heating only models, cascaded reverse return with zone valves.

Page 9
Cascading the FT Series ‘Heating Only’ Boiler
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMPL N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Cascade System Sensor (18 Gauge Wire)
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMPERATURE
SENSOR
DHW PUMP
N GL N GSYSTEM PUMPLN G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Wiring Diagram for Cascaded Reverse Return with Zone Valves
Floor Model Boiler 1 (Lead)
Floor Model Boiler 2 (Follow)
P1
POWER IN
T T
ZONE 1 T T
ZONE 2 T T
ZONE 3 T T
ZONE 4
OFF
ON
END
SW.
MODE
ZONE VALVE CONTROL
FOUR ZONE,
WITH OPTIONAL PRIORITY
NORMAL RESET
THERMOSTAT
ZONE 1
1 2 3 4 1
ZONE 4 PRIORITY
2 3 4
ZONE 2
1 2 3 4
ZONE 3
1 2
THERMOSTAT
3 4
ZONE 4
JUMPER 3&4
2 WIRE ZONE VALVE (NO END SWITCH)
3 WIRE ZONE VALVE (POWER OPEN
4 WIRE ZONE VALVE SELFCLOSING)
1 2 3
MOTOR END
SW.
FUSE (3 AMPMAX)
24 VAC
INPUT
DRY CONTACTS
N/0 C N/C
POWER
THERMOSTAT
Outdoor Sensor (18 Gauge Wire)
Line Voltage Terminals Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
(14 Gauge Wire) Optional External
Low Water Cutoff
(Factory Jumper Installed)
Line Voltage Terminals Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
(14 Gauge Wire) Optional External
Low Water Cutoff
(Factory Jumper Installed)
Generic Zone Valve Controller
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! See Section 1.D on page 5
Figure 9. Wiring diagram for cascaded reverse return with zone valves.

Page 10
Cascade FT Floor Heating Only Boilers Piping and Wiring Diagrams (continued)
See Section 1.B on page 3 for common pipe sizes for system and return/supply headers for different system Delta T’s.
See SECTION 3 on page 22 for cascade kit details.
WARNING: This drawing shows suggested piping conguration and valving. Check with local codes and ordinances for additional requirements.
See Section 1.C on page 4 for reference to adjust the internal LLH valves (V-1, V-2, V-3) to their proper positions PRIOR to boiler installation.
Figure 10. Two FT oor heating only models, cascaded reverse return with zone pumps.

Page 11
Cascading the FT Series ‘Heating Only’ Boiler
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMPL N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Cascade System Sensor (18 Gauge Wire)
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMPERATURE
SENSOR
DHW PUMP
N GL N GSYSTEM PUMPLN G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
INPUT120 VOLTCIRCULATORS
X X
END
SWITCH ZC
120V RELAY
FUSE 1AMP
SLAVE
MASTER
1234ZONE 4
PRIORITY
ON OFF
POWER
ZONE 2ZONE 3
FOURZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
PLUG-IN CARDS
RESET NORMAL
SR 504-EXP
T'STATS
ZONE 1
ZONE 3
POWER
ZONE 1ZONE 2
ZR
Wiring Diagram for Cascaded Reverse Return with Zone Pumps
Floor Model Boiler 1 (Lead)
Floor Model Boiler 2 (Follow)
P3 P2 P1
Outdoor Sensor (18 Gauge Wire)
Line Voltage Terminals Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
Line Voltage Terminals Low Voltage TerminalsLow Voltage Terminals
(14 Gauge Wire)
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
(14 Gauge Wire) Optional External
Low Water Cutoff
(Factory Jumper Installed)
Optional External Low Water Cutoff
(Factory Jumper Installed)
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! See Section 1.D on page 5
Generic Pump Controller
Figure 11. Wiring diagram for cascaded reverse return with zone pumps.

Page 12
Cascade FT Floor Heating Only Boilers Piping and Wiring Diagrams (continued)
See Section 1.B on page 3 for common pipe sizes for system and return/supply headers for different system Delta T’s. See SECTION 3 on page 22 for cascade kit details.
WARNING: This drawing shows suggested piping conguration and valving. Check with local codes and ordinances for additional requirements.
See Section 1.C on page 4 for reference to adjust the internal LLH valves (V-1, V-2, V-3) to their proper positions PRIOR to boiler installation.
Figure 12. Two FT oor heating only models, cascaded reverse return with pumps and indirect.

Page 13
Cascading the FT Series ‘Heating Only’ Boiler
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMP
Outdoor Sensor (18 Gauge Wire)
L N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Cascade System Sensor (18 Gauge Wire)
Line Voltage Terminals Low Voltage Terminals
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMPERATURE
SENSOR
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
DHW PUMP
N GL N GSYSTEM PUMPLN G
MAIN POWER
(14 Gauge Wire)
Line Voltage Terminals Low Voltage Terminals
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
(14 Gauge Wire)
L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
INPUT120 VOLTCIRCULATORS
X X
END
SWITCH ZC
120V RELAY
FUSE 1AMP
SLAVE
MASTER
1234ZONE 4
PRIORITY
ON OFF
POWER
ZONE 2ZONE 3
FOURZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
PLUG-IN CARDS
RESET NORMAL
SR 504-EXP
T'STATS
ZONE 1
ZONE 3
POWER
ZONE 1ZONE 2
ZR
Wiring Diagram for Cascaded Reverse Return with Pumps and Indirect
Floor Model Boiler 1 (Lead)
Floor Model Boiler 2 (Follow)
P4 DHW
Temperature
Sensor or Aquastat
(18 Gauge Wire)
P3 P2 P1
Optional External Low Water Cutoff
(Factory Jumper Installed)
Optional External Low Water Cutoff
(Factory Jumper Installed)
Optional
External
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! See Section 1.D on page 5
Generic Pump Controller
Figure 13. Wiring diagram for cascaded reverse return with system pumps and indirect.

Page 14
Figure 14. Two FT oor heating only models, cascaded reverse return with
low temp zones and air handlers.
Cascade FT Floor Heating Only Boilers Piping
and Wiring Diagrams (continued)
See Section 1.B on page 3 for common pipe sizes for system and return/supply headers for different system Delta T’s.
See SECTION 3 on page 22 for cascade kit details.
WARNING: This drawing shows suggested piping conguration and valving. Check with local codes and ordinances for additional requirements.
See Section 1.C on page 4 for reference to adjust the internal LLH valves (V-1, V-2, V-3) to their proper positions PRIOR to boiler installation.

Page 15
Cascading the FT Series ‘Heating Only’ Boiler
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
DHW PUMP
N GL N G SYSTEM PUMP
Outdoor Sensor (18 Gauge Wire)
L N G
MAIN POWER L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Cascade
System
Sensor
(18 Gauge Wire)
Line Voltage Terminals Low Voltage Terminals
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMPERATURE
SENSOR
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
POWER TO 24V
TRANSFORMER
(14 Gauge Wire)
Low Voltage Terminals
Line Voltage Terminals Low Voltage TerminalsLow Voltage Terminals
DHW PUMP
N GL N GSYSTEM PUMPLN G
MAIN POWER
(14 Gauge Wire) (14 Gauge Wire)
L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Wiring Diagram for Cascaded Reverse Return with Low Temp Zones and Air Handlers
P1 P2


TT1
TT2
Optional External
Low Water Cutoff
(Factory Jumper Installed)
Optional External
Low Water Cutoff
(Factory Jumper Installed)
Floor Model Boiler 1 (Lead)
Floor Model Boiler 2 (Follow)
Figure 15. Wiring diagram for cascaded reverse return with
low temp zones and air handlers.
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! See Section 1.D on page 5

Page 16
Cascade FT Floor Heating Only Boilers Piping and Wiring Diagrams (continued)
See SECTION 3 on page 22 for cascade kit details.
See Section 1.C on page 4 for reference to adjust the internal LLH valves (V-1, V-2, V-3) to their proper positions PRIOR to boiler installation.
WARNING: This drawing shows suggested piping conguration and valving. Check with local codes and ordinances for additional requirements.
Figure 16. Three FT oor heating only models, cascaded reverse return
with zone pumps and indirect.

Page 17
Cascading the FT Series ‘Heating Only’ Boiler
Line Voltage Terminals Low Voltage Terminals
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMP.
SENSOR
Low Voltage Terminals
DHW PUMP
N GL N G SYSTEM PUMPL N G
MAIN POWER
(14 Gauge Wire)
L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Line Voltage Terminals Low Voltage Terminals
2-stage aquastat
part # RE09320
R 0-10V W (+) INPUT (-)
LWC O/ST/T
R B W
AC24V
OUTPUT DHW
TEMPERATURE
SENSOR
Low Voltage Terminals
DHW PUMP
N GL N GSYSTEM PUMPLN G
MAIN POWER
(14 Gauge Wire)
L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
INPUT120 VOLTCIRCULATORS
X X
END
SWITCH ZC
120V RELAY
FUSE 1AMP
SLAVE
MASTER
1234ZONE 4
PRIORITY
ON OFF
POWER
ZONE 2ZONE 3
FOURZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
PLUG-IN CARDS
RESET NORMAL
SR 504-EXP
T'STATS
ZONE 1
ZONE 3
POWER
ZONE 1ZONE 2
ZR
Wiring Diagram for Cascaded Reverse Return with Zone Pumps and Indirect
P4
DHW Aquastat Stage 1
(18 Gauge Wire)
P3 P2 P1
Line Voltage Terminals Low Voltage Terminals
R 0-10V W (+) INPUT (-)
LWC O/ST/T
AC24V
OUTPUT DHW
TEMPERATURE
SENSOR
Low Voltage Terminals
DHW PUMP
N GL N GSYSTEM PUMPLN G
MAIN POWER
(14 Gauge Wire)
L/ZC L-T/T PUMP
N GL/ZC L-T/T
CASCADE
SYSTEM
SENSOR
Optional External
Low Water Cutoff
(Factory Jumper Installed)
Optional External
Low Water Cutoff
(Factory Jumper Installed)
Optional External
Low Water Cutoff
(Factory Jumper Installed)
Outdoor Sensor
(18 Gauge Wire)
Cascade
System Sensor (18 Gauge Wire)
DHW Aquastat Stage 2
(18 Gauge Wire)
Power to 24V
Transformer
(14 Gauge Wire)
Power to 24V
Transformer
(14 Gauge Wire)
Power to 24V
Transformer
(14 Gauge Wire)
Floor Model Boiler 1 (Lead)
Floor Model Boiler 2 (Follow) Floor Model Boiler 3 (Follow)
NOTE: The terminal blocks are NOT the same on the oorstanding VS the wall-mounted models! See Section 1.D on page 5
Generic Pump Controller
Figure 17. Wiring diagram for cascaded reverse return
with zone pumps and indirect.

Page 18
Mixing Valve
Zone Valve
Actuators
Circulation pump Pressure relief valve
Air separator
Expansion tank
(Diaphragm type)
Isolation valve
Check valve
2-way valve
Indirect DHW Tank
Air Separator
Pressure Reducing
Valve
Purge
Cascade System
Sensor
Tee
Make Up Water
NOTE: These drawings
are meant to show system
piping concept only.
Installer is responsible for
all equipment and detailing
required by local codes.
NOTE: The cascading
communications cable
is 60" long. This must
be considered during
installation as this leaves
only about 12" between
adjascent units.
2.B Cascade FT
Wall-Mounted
Heating only
Boilers Piping
Leader Follower
PRIMARY/SECONDARY
CONNECTION
SUPPLY
PRIMARY LOOP
(SPACE HEATING)
SECONDARY LOOP (SPACE HEATING)
SUPPLY
RETURN
CASCADE
SYSTEM
SENSOR
Do not exceed 12" apart
RETURN
MAKE UP
WATER
12"
Max
Figure 18. Two FT wall-mounted heating only models, cascaded primary secondary.

Page 19
Cascading the FT Series ‘Heating Only’ Boiler
NOTE: These drawings
are meant to show system
piping concept only.
Installer is responsible for
all equipment and detailing
required by local codes.
NOTE: The cascading
communications cable
is 60" long. This must
be considered during
installation as this leaves
only about 12" between
adjascent units.
Leader Follower
CASCADE
SYSTEM
SENSOR SUPPLY
RETURN
RETURN
SUPPLY
PRIMARY LOOP
(SPACE HEATING)
PRIMARY/SECONDARY
CONNECTION Do not exceed 12" apart
SECONDARY LOOP (SPACE HEATING)
ZONE 1
ZONE 2
ZONE 3
12"
Max
Figure 19. Two FT wall-mounted heating only models, cascaded with zone valves.

Page 20
SUPPLY
RETURN
SUPPLY
RETURN
CASCADE SYSTEM
SENSOR
SUPPLY
RETURN
LOW LOSS
HEADER
MAKE UP
WATER
Leader Follower Follower
NOTE: These drawings are meant to show system piping concept only. Installer
is responsible for all equipment and detailing required by local codes.
NOTE: The cascading communications cable is 60" long. This must be considered
during installation as this leaves only about 12" between adjascent units.
Cascade FT Wall-Mounted, Heating Only Boilers Piping Diagrams (continued)
Mixing Valve
Zone Valve
Actuators
Circulation pump Pressure relief valve
Air separator
Expansion tank
(Diaphragm type)
Isolation valve
Check valve
2-way valve
Indirect DHW Tank
Air Separator
Pressure Reducing
Valve
Purge
Cascade System
Sensor
Tee
Make Up Water
Figure 20. Three FT wall-mounted heating only models, cascaded and with low loss header.