IBC V-10, Manual, Page: 28 / 103

2.7 Combining loads
As a control strategy, load combining is used when two rooms or zones in a building have different
temperatures. Running two loads at compatible temperature settings at the same time provides
added efficiency and heating comfort. This feature allows two compatible loads to run
simultaneously; that is, they are "combined" to service their loads at the same time. To set
different rooms or zones in a building with the same temperature, see
Syncing zones with "Zone
Of" on page 51 .
The main principle for load combining is that the target temperature and the load’s minimum and
maximum supply temperatures (+/- differential temperature) in the primary and secondary loads
must overlap. With the boiler’s load priority scheme, load combining functions only while the
primary load is the active load. Note that any system or load temperature limits will still be in
effect.
In load combining there are two modes: Basic mode and Full mode. Basic mode should cover
most of the load combining applications. Use the full mode when the load is not using a mixing
valve. Suppressing the higher temperature rather than overshooting the lower temperature may be
required.
Note
For Reset Heating or External Control loads, the target temperature is dynamic.
Therefore, it is possible that as outdoor and/or indoor temperatures change, reset and
external control heating loads could switch in and out of compatible temperatures.
For instructions on using the Load Combining feature, see Combining two loads to service two
loads at the same time on page 55 .
2.7.1 Basic mode load combining (default) - recommended
Basic (simple) mode allows any two of the four loads to be combined together by setting a
primary and secondary load.
Parameter Default Minimum Maximum
Primary Load Disabled Load 1 Load 4
Secondary Load Disabled Load 1 Load 4
The boiler supplies a target water temperature based on the highest water temperature required
between both loads.
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Section: Operating concepts