IBC SL 35-199 Operating Instructions Manual page 30

NOTE
For further information and
details regarding Multiple
Boiler application, consult
our Technical Notes - Multiple
Boiler Systems. These notes
provide necessary detail on
specific single and multiple
boiler applications "Piping",
"Wiring" and "Settings".
(available at www.ibcboiler.
com or from your IBC
Representative).
1-24
SL 35-199, SL 45-260 MODULATING GAS BOILERS
Check valves or thermal traps should be used to isolate both the supply and
return piping for each load - to avoid thermal siphoning and reverse flow.
To ensure adequate water flow through the boiler under high-head / single
zone space heating conditions, a pressure activated bypass or other means of
bypass must be used on any load where the flow rate might drop below minimum
requirements (6 USgpm).
For further information and details, consult our Application Notes – which provide
detail on specific single and multiple boiler applications "Piping", "Wiring" and
"Settings". (available at www.ibcboiler.com or from your IBC Representative).
MULTIPLE BOILER PIPING - BENEFITS AND INSTALLATION RULES
Multiple IBC boilers can be installed in a single heating system to provide
redundancy, increased output, and greater heating plant turn-down capabilities.
Primary/Secondary piping must be employed, and each boiler must be installed
with its own pump as illustrated below. This approach provides constant head
and flow at each boiler, regardless of flow variations in the main building loop.
Figure 28: Multiple boiler piping concept
Each boiler will control its own pump, turning it off or on when heat is required.
This approach saves electricity by reducing the pumping power required as load
conditions are reduced. One boiler control is set up as a "Master" boiler, and up
to 23 additional boilers can be added to the system as "Subordinate" boilers by
connecting a twisted pair of wires between the boilers. No additional controls are
needed.
Check valves are to be used in each boilers piping to prevent reverse flow when
the boiler is off.
For further information and details, consult our Application Notes – which provide
detail on specific single and multiple boiler applications "Piping", "Wiring" and
"Settings". (available at www.ibcboiler.com or from your IBC Representative).
INSTALLATION AND OPERATION INSTRUCTIONS