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Series 8900SH Control Panel Operation And Installation Manual
Section 9 Fine Tuning The Heating System
SECTION 9: FINE TUNING THE HEATING SYSTEM
The key to fine tuning any boiler system is to understand the building use. A hospital, an office
building, a school, and an apartment all have very different hosting needs.
The following codes are used to fine tune a system’s heating output:
Codes 30 to 37 - Setback Temperature.
Code 21 - Outside Air Temperature Shut Down.
Code 22 - Minimum Return Water Line Temperature.
Code 23 - Outdoor Reset Ratio Setting.
Code 24 - Rate of Change Factor.
The goal of fine tuning a system is to find a balance between the comfort of the occupants and
the cost of operation. Boiler staging is a function of building needs, not outside temperature or
Return Water Line temperature. The following provides a step-by-step way to improve the
settings.
Codes 30 to 37:
First, determine the times each day that the heat can be set back using Codes 30 – 37. Some
buildings, such as hospitals, are always occupied, and thus do not allow for much, if any,
setback. However, in a normal office building temperatures can be reduced by 20°F overnight
and on weekends (the maximum recornrnended by TRIAD). Setback can be as much as 20°F
because the control panel begins determining the most fuel efficient way to reheat the building
two hours
prior to the end of the setback period instead of just firing all the boilers
simultaneously. While watching both the outside temperature and the system Return Line
Temperature, the panel will fire the boiler(s) only enough to bring the heat back normal. So the
energy savings realized during setback are not wasted by firing all the boilers at the last
minute.
Remember that the panel is capable of 4 setbacks every 24 hours, so setback can also be
scheduled, for example, in the afternoon when the sun and body heat from the occupants, can
naturally contribute to warming the building.
Code 21:
The setback function in codes 30-37 are now operating and the building cools off when vacant
and warms back up when occupied. The next step is to use Code 21 to slowly reduce the
outside air shutoff temperature degree by degree. If the current setting is 60°F, once a week
reduce the setting by 1°F. The goal is to reduce the heat to the lowest temperature the
occupants will comfortably allow. If it becomes too cold increase the set point by 1°F.
Code 22:
Next, begin reducing the minimum system Return Line Temperature by 1°F each week using
Code 22. If the starting temperature is 100°F, reduce it to 99°F for a week, and every week
thereafter, until the building is comfortable. If it becomes too cold, then increase the set point
by 1°F.