AERCO AM Series Boiler User Manual - Manual (Page 25)

AM Series Boilers and Water Heaters
CHAPTER 2 – FUNCTIONAL OVERVIEW
OMM-0100_0B AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 25 of 156
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2.5.4 Boiler Efficiency in Outdoor Reset Mode
When the outdoor reset is activated (an outside sensor is connected), this boiler is designed to
always work at the maximum efficiency. It will automatically change the supply temperature in
relation with the outdoor temperature (Outdoor reset). The graph in Figure 2-12 shows a typical
system. Outdoor reset curves are adjustable.
.
Figure 2-12: Outdoor Reset Control Efficiency Graph
This graph represents an installation where the supply and return temperatures are 139°F and
115°F respectively, and the outside temperature is 23°F. The outdoor reset drives the boiler, to
progressively reduce the supply temperature and thereby optimize the efficiency. It changes
from 87% when outside is -10°F, to 94.8% efficiency when outdoor temperature is 23°F, and up
to 98% efficiency when the outside temperature rises up to 67°F.