heat-timer Mini-MOD-CNC Installation And Operation Manual page 31

OFFSET
Adjustable from 50Fº/28Cº to –50Fº/–28Cº
Button: MENU/Set Point/Offset
• The Offset setting lets you adjust the starting points of the Reset Ratio curves. This
means that, regardless of the Outdoor temperature (OD), 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 0F° to 10F° (an increase of 10F°), then the
Set Point temperature would increase to 140°F
• The Offset setting does not change the ratio selection. For instance, with 1.00 (OD):1.00
(SYS) Reset Ratio, the System water temperature (SYS) will always increase one degree for
each degree change in the Outdoor temperature (OD). What the Offset does is add or
subtract a constant temperature value. See "OUTDOOR RESET CONCEPT" on page 9.
If required: Adjust the Water Offset in mild weather. If the ambient building
•
temperatures are too warm in mild weather, decrease the offset. If the ambient building
temperatures are too cold in mild weather, increase the Water 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 temperature. In radiant heat applications, change the offset 1°F or 2°F for every
1°F you wish to change the building temperature.
OUTDOOR CUTOFF TEMPERATURE
Adjustable: Off, from 20ºF/70ºC—100ºF/38ºC, On
Button: MENU/Set Point/Outdoor Cutoff
• The Outdoor Cutoff screen will automatically appear after the offset has been selected.
• When the outdoor temperature falls to the adjustable Outdoor Cutoff temperature, the
Mini-MOD-CNC will control and modulate boilers to hold the calculated temperature.
• When the outdoor temperature rises to the Outdoor Cutoff plus a 2°F differential, the
Mini-MOD-CNC will turn all boilers off.
• The System relay will remain energized for the Run-On delay then de-energize.
• The Outdoor Cutoff can be set from 20°F to 100°F. In addition, it can be set to ON or
OFF. In the ON position, the System Relay will run regardless of the Outdoor temperature
(OD) and the burner stages will be active to hold the calculated water temperature.
(Note: The lowest water temperature the Mini-MOD-CNC will circulate is 70°F. If the
Outdoor Cutoff is turned ON and the Season is set to Winter, the Mini-MOD-CNC will
circulate at least 70°F water even in the hottest of weather.) In the OFF position, the
system pump will always be off and all burner stages will be off.
059102-00 REV. C
14 OPERATING MENU SEQUENCE
Default: 0Fº/0Cº
Default: 65ºF/18ºC
------- OFFSET ------
OFFSET
+0 o
F
+0°F
[
▲ ▼
BACK SAVE
BACK
Offset=10°F Min Target=120°F
Reset Ratio=1.5 : 1.0 Max Target=170°F
180
170
Max Target
160
150
140
130
Min Target
120
110
100
70 60 50 40 30 20 10
Outdoor Temperature (in °F)
Target Offset
MINIMUM WATER TEMP
70 o
F
[
OUTDOOR CUTOFF
▲ ▼
BACK SAVE
65°F
Point1: System=120°F Point2: System=170°F
Oudoor=60°F Oudoor=0°F
Max Target
180
BACK
170
160
150
140
130
Point1 Min Target
120
110
100
70 60 50 40 30 20 10
Outdoor Temperature (in °F)
Custom Reset Ratio
HEAT-TIMER CORP.
]
SAVE
0 -10 -20
]
SAVE
Point2
0 -10 -20
|
31