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
5
6
7
8
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
3
4
4
4
Table 2: Common Pipe Sizing for
∆
T= 35 F (Speed 2)
Model/# of units
1
2
3
4
5
6
7
8
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
5
6
7
8
100
3/4"
1"
1-1/4"
1-1/2"
2
2
2
2
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
