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Operation
Altering the Indoor/Outdoor Control Settings
Slope adjustment
6
The adjustable high limit determines the maximum available boiler (supply)
temperature. Therefore, it functions as a high limit.
The room thermostat (if used) enables and disables the outdoor reset processor in
order to add indoor control (fine tuning) to the outdoor reset function.
The curve for the outdoor reset function can be adjusted by opening the front
flip-down cover.
Factory settings
Heating curve slope
"
"
selection = 1.2
Warm weather shut-down (WWSD)
"
"
selection = 70 °F / 21 °C
IMPORTANT
If there is no call for heat from the room
thermostat, the burner will not be
activated, even if the heating curve
setting calls for a higher temperature.
As outdoor temperatures drop, heat
losses from a space become greater and
the heating system supply water
temperature must be raised to maintain a
constant room temperature. The heating
curve value describes how many degrees
the supply water temperature is raised for
a one degree drop in outdoor
temperature. The supply temperature
starts to increase when the outdoor
temperature falls below the warm
weather shut-down (WWSD) setting.
To calculate the correct setting for the
heating curve, use the following formula:
heating curve slope =
design supply temp. - WWSD temp.
WWSD temp. - design outdoor temp.
Example:
design outdoor temp.:
70 ˚F / 21 ˚C
WWSD temperature:
160 ˚F / 71 ˚C
design supply temp.:
heating curve slope =
160 ˚F - 70 ˚F
90 ˚F
=
70 ˚F - 5 ˚F
65 ˚F
For further assistance, please see section
entitled "Helpful hints."
5 ˚F / -15 ˚C
= 1.4
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