•If required: Adjust the RESET RATIO in cold weather. If the ambient building temperatures are too cold in cold weather, move the ratio to a higher selection. That is, if 1.00 (O):1.00 (S) was initially selected, change the selection to 1.00 (O):1.25 (S). If the building temperatures are too warm in cold weather, move the ratio to a lower selection. That is, if 1.00 (O):1.00 (S) was initially selected, change the selection to 1.25 (O):1.00 (S).
•The Custom option gives the user the capability of creating a specialized Reset Ratio curve. Setting two points on the Reset Ratio chart generates the customized curve. Each point requires a System Water Temperature SYS and an Outdoor Temperature OD. The line connecting the two points will be the reset ratio. The Offset, Minimum Target and Maximum Target settings will still apply to the customized curve.
Custom Outdoor Reset Curve | Set SYS Temp 1: |
100 F | |
Options: Sys Temp 1, 2 | Default: 1(100ºF/38ºC), 2(171ºF/77ºC) |
Options: Outdoor Temp 1, 2
SET /<Out. Reset>/Reset Ratio/Custom
•For situations where the standard reset ratios do not provide the perfect building
•The Custom Reset Ratio is only available when Custom is selected from the Reset Ratio menu. It provides the user with the capability of assigning two points on the reset ratio diagram and use the line that connects those two points as the customized reset ratio curve. Each of the two points will need a specific System and Outdoor Temperature to identify it on the diagram.
•To Specify the first point, set Sys Temp 1, and OD Temp 1. Then, set Sys Temp 2, and OD Temp 2, to set the second point on the curve. The two points can be any where on the line, not necessarily at the ends.
•The chart shows an example of a customized curve 6(O):5(S) that does not exist in the standard curve options. If the outdoor temperature reaches 30ºF, the system target will be 145ºF.
•Remember that the Min Target and Max Target apply to all reset ratios including the custom reset ratio ones.
At OD Temp 1: 70
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| Point1: System=120°F |
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(in | 160 |
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Temperature |
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150 |
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140 |
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130 |
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Water | 120 |
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| 70 | 60 | 50 | 40 | 30 | 20 | 10 | 0 | |
Outdoor Temperature (in °F)
Custom Reset Ratio
Offset (Available when Startup Control Mode = Outdoor Reset) | Offset: | |
Options: From | Default: 0ºF/0ºC | +0 F |
SET /<Out. Reset>/Offset
•The Offset setting adjusts the starting points of the Reset Ratio curves. This means that, regardless of the Outdoor temperature or the Reset Ratio, when the Offset setting is changed, that change is directly added to or subtracted from the calculated Target. For example, if the Set Point temperature was 130°F and the Offset was changed from 0° to +10°, then the Set Point temperature would increase to 140°F
•If required: Adjust 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. See Type of Radiation in Building Table on page 2.
Outdoor Cutoff |
| Cutoff: |
Options: Off, 30ºF/0ºC to 75ºF/25ºC, On | Default: 60ºF/16ºC | 60 F |
/Set Point/Cutoff | in Set Point |
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SET /Set Point/<Out. Reset>/Cutoff | in Reset |
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•In Set Point Mode, if the outdoor sensor is installed, the Outdoor Cutoff setting screen will automatically appear after the temperature Set Point has been selected.
•The Outdoor and Cutoff temperatures can be viewed from the default screen by clicking the Up or Down buttons.
•When the outdoor temperature falls to the adjustable Outdoor Cutoff temperature, the
•When the outdoor temperature rises to the Outdoor Cutoff plus a 2°F differential, the
•The Outdoor Cutoff can be set from 30°F to 75°F. In addition, the Setting can be set to ON or OFF. If ON is selected, the System Relay will run regardless of the Outdoor temperature and the boilers will be active to hold the calculated water temperature. If OFF is selected, the System and Boiler relays will always be off.
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