IBC V-10, Manual, Page: 20 / 103

2.2 Reset heating
In a typical hot water heating system, a thermostat in a building signals a call for heat, causing the
boiler to circulate hot water to that space until the thermostat setting is reached. This can be
inefficient, requiring several burn on/off cycles, which may overshoot or undershoot the
requirement, due to heat loss and outdoor temperature variation. That is, the amount of heat lost in
a building changes according to the outdoor temperature. And the greater the difference between
the temperature inside and the temperature outside, the greater the heat loss.
Figure 5 Heat loss vs outdoor temperature
The controller's Reset Heating or outdoor reset mode is a way of balancing the heat lost in a
building with the heat supplied to the building. The Reset Heating mode uses a temperature
management algorithm to automatically adjust or "reset" the supply/outlet water temperature to
compensate for the differing rates of heat loss that a building experiences as the outdoor
temperature changes.
Note
Reset Heating mode requires the installation of an outdoor temperature sensor (supplied
with boiler).
The controller's default Set Point mode sets the boiler temperature to accommodate the estimated
coldest day of the year. However, the controller's Reset Heating mode will promote energy savings
by adjusting the higher setting down based on the outdoor temperature at any particular time of day.
When applied to IBC's condensing boilers, the Reset Heating mode enables efficiency benefits by
lowering the required circulating water temperature, so that cooler water returns to the boiler
(promoting more condensation). Its temperature control uses lower water heating temperatures for
outdoor temperatures above the coldest day expected.
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Section: Operating concepts