IBC V-10, Operating Instructions Manual

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OPERATING INSTRUCTIONS
18
V-10 TOUCH SCREEN BOILER CONTROLLER
1.7.3 - Reset Heating
The boiler offers Reset Heating or outdoor reset control as standard equipment;
this feature coordinates the control of boiler supply/outlet water temperature for
space heating with the outdoor temperature. Reset Heating offers enhanced
comfort and efficiency by using variable supply water temperatures to
compensate for the differing rates of heat loss that a building experiences as the
outdoor temperature changes. At any outdoor temperature above the coldest day
expected, it automatically uses lower heating temperatures than would otherwise
be used. This saves energy without sacrificing comfort.
When applied within a condensing boiler, outdoor reset control offers direct and
significant combustion efficiency benefits by allowing generally lower circulating
water temperature. This provides cooler return water to the boiler, promoting
more condensation (= energy capture).
Contacts are provided for connection of an outdoor sensor (shipped with each
boiler) to be placed in an appropriate outdoor position (typically on the north
face of the building away from any heat source). The temperature management
algorithm flexes the boiler supply temperature according to characterized heating
curves that are automatically called up through the load declaration process.
Curves are provided for each of the radiation terminal types offered - e.g. High or
low mass radiant floor, air handler, finned tube baseboards etc.
In an “open loop” reset system, a room or zone thermostat is used to send a call
for heat over a 24VAC lead; this opens the respective zone valve, and signals
the boiler to fire using onward leads to the boiler’s dry contacts (use one of the
connections marked “Therm 1, 2, 3 or 4” on the TB2 terminal strip). Gang such
leads in parallel from multiple zone valves for single connection to the boiler.
Note that typical room thermostats simply provide a call for heat, they do not
control the circulating water temperature from the boiler in an open loop reset
system. Adjustment of a room thermostat from 72°F/22°C to 86° F/30°C will
make no further difference to the delivered temperature if the floor slab has
stabilized at the boiler temperature determined by the reset curve.
Where outdoor reset is applied without the indoor sensor feedback option, some
manual adjustment may be required to achieve the desired comfort level. Fine
adjustment can be made by editing the Indoor Setpoint ° variable, on the Reset
NOTE
If there is no outdoor
temperature sensor the
controller assumes 32°F/0°C
to determine the heating
curve.