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18
BSC Installation and Operation Manual
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temperature and the stages will modulate to hold the target set point.
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RESET RATIO
(1.00ºOD : 4.00ºSys) to 12 (4.00ºOD : 1.00ºSys) Default: 1(1.00ºOD : 1.00ºSys)
SELECT: MENU/Set Point/Reset Ratio In Outdoor Reset Only
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outdoor temperature. With any of the ratios, the colder it becomes outside, the hotter
the temperature of the system water.
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rapidly as the outside temperature falls, hitting 240°F at 35°F outside temperature.
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as the outside temperature falls. Even at -30°F, the system water will only be 125°F,
and at 22°F outside, the system water will be 112°F. Such a low Reset Ratio might be
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---- RESET RATIO ----
1.00 OD=4.00 Sys
1.00 OD=3.00 Sys
1.00 OD=2.00 Sys
1.00 OD=1.50 Sys
1.00 OD=1.25 Sys
1.00 OD=1.00 Sys
1.25 OD=1.00 Sys
1.50 OD=1.00 Sys
2.00 OD=1.00 Sys
3.00 OD=1.00 Sys
4.00 OD=1.00 Sys
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ratio, for every degree the outside temperature falls, the system water temperature is increased one degree.
,IUHTXLUHG Adjust the RESET RATIO in cold weather. If the ambient building temperature are cold in cold weather, move the
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$IWHUVHOHFWLQJWKH5HVHW5DWLRSUHVVLQJWKHADJUST/SELECT button will switch to the Offset setting option.
OFFSET
Adjustable from +40Fº/+22Cº to (-40Fº/-22Cº) Default: 0Fº/0Cº
SELECT: MENU/Set Point/Offset in Outdoor Reset only
(Available with Reset Modes Only)
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of the Outdoor temperature, or the Reset Ratio that has been selected, when the Offset
setting is changed, that change is directly added to or subtracted from the calculated
temperature. For example, if the Set Point temperature was 130°F and the Offset was
changed from 0° to 10° (an increase of 10°), the Set Point would increase to 140°F.
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degree for every 1.5 degree change in the Outdoor temperature. What the Offset does
is add or subtract a constant temperature value.
,IUHTXLUHGAdjust the Water Offset in mild weather. If the ambient building
temperatures are too warm in the mild weather, decrease the Offset. If the ambient
building temperatures are too cold in the mild weather, increase the Offset. The rule
of thumb for baseboard radiation is to change the Offset 4°F for every 1°F you wish to
change the building temperatures. In radiant heat applications, change the Offset 1°F
or 2°F for every 1°F you wish to change the building temperature.
-------- OFFSET -------
0
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Outdoor Temperature (in °F)
70 60 50 40 2030 0 -1010
-20
120
140
130
150
160
170
180
100
110
Water Temperature (in °F)
Target Offset
Offset=10°F
Reset Ratio=1.5 : 1.0
Reset Ratio
Max Target
Min Target
Reset Ratio + 10F Offset
Min Target=120°F
Max Target=170
°F
MINIMUM WATER TEMPERATURE
Adjustable from 70ºF/21ºC to 180ºF/82ºC Default: 140ºF/60ºC
SELECT: MENU/Set Point/Reset Ratio/Offset/Outdoor Cutoff/Min Wtr Temp
(Available with Reset Modes Only)
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the Reset Ratio, and the Offset value. The BSC will control all boilers to hold either
the Set Point temperature, or the Minimum Target, whichever is higher.
MINIMUM WATER TEMP
140
F
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