IBC SL Series Installation & Operating Manual page 54

Note
The boiler, when used in connection with a refrigeration system, must be installed
so that the chilled medium is piped in parallel with the boiler with appropriate
valves to prevent the chilled medium from entering the boiler.
The boiler piping system of a hot water boiler connected to the heating coils
located in air handling units where they may be exposed to refrigerated air
circulation must be equipped with flow control valves or other automatic means to
prevent gravity circulation of the boiler water during the cooling cycle.
Monitor the performance of system components when using the sequential load
feature of the boiler to ensure that the components are compatible. For instance,
many air handlers have a thermostat connection that will energize an internal relay
to operate the air handler circulator and its fan on a call for heat. This may result in
the air handler components operating when other loads are operating at a higher
priority, resulting in cold air blowing, or heat robbed from another load. Some
wiring alterations may be required to separate these functions from the thermostat
control in favor of more effective control from the boiler.
Figure 33 Primary-secondary piping with simultaneous heating calls. Always ensure that loads
sensitive to high temperatures (e.g., radiant floors), are protected using appropriate means such as a
manual mixing valve, or an aquastat (set to 130°F, for example) wired to the boiler's auxiliary
interlocks.
50
Section: Installation