U.S. Boiler Company ASPEN ASPN-085, Installation, Operating And Service Instructions, Page: 123 / 180

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XII. Operation
F. Changing Adjustable Parameters (continued)
The Control is shipped with defaults that will provide improved operation. Adjustment is only required to optimize setup.
The expected heat rate adjustment is used to better match boiler output to the home heating needs. After receiving a “call for
heat” the Control first uses the expected heat rate value to set a maximum heat rate. The maximum heat rate is the highest heat
rate that the boiler can fire to at that moment. The maximum heat rate is the summation of the expected heat rates for the active
(turned on) zones. After establishing the maximum heat rate the Control then measures water temperature and fires the boiler only
as hard as required for the heat demand.
Expected Heat Rate Adjustment Screens (HeatMatch Software)
Example “call for heat”
durations for a four zone
house.
Maximum heat rate
limits firing rate and
prevents the Control
from firing to 100% in
response to a smaller
zone demands.
Maximum Heat Rate:
Automatically adjusted
by the Control based on
the size and number of
zones calling for heat.
Actual Heat Rate:
Boiler is free to
modulate based on
temperature from
minimum to maximum
heat rate.
Figure 12.11: Four Zone House (with Zone Control Connected)
Figure 12.12: Expected Heat Rate Adjustment (with Zone Control Connected)