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BMC and BMC-6X Installation and Operation Manual
OUTDOOR CUTOFF TEMPERATURE
Adjustable Off, from 20ºF/ to70ºC - 100ºF, On Default: 60ºF/ 16ºC
Button: MENU/Set Point/Outdoor Cutoff in Set Point
Button: MENU/Set Point/Offset/Outdoor Cutoff in Reset
• If the outdoor sensor is installed, the Outdoor Cutoff screen will automatically appear
after the temperature Set Point has been selected.
• When the outdoor temperature falls to the adjustable Outdoor Cutoff temperature, the
BMC will control and modulate boilers to hold the calculated temperature.
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------- OUTDOOR CUTOFF -------
65 F
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• When the outdoor temperature rises to the Outdoor Cutoff plus a 2°F differential, the BMC 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, the Setting 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 BMC will circulate is 70°F. If the Outdoor Cutoff is turned ON
and the Season is set to Winter, the BMC 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.
OFFSET
Adjustable from 50Fº/28Cº to (-50Fº/-28Cº) Default: 0Fº/0Cº
Button: MENU/Set Point/Offset in Reset only
• 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 0° to 10° (an increase of 10°), then the Set
Point temperature would increase to 140°F
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-------------- OFFSET -------------
+0 F
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• 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 Understanding Operation Concept on page 5)
• If required: Adjust the Water Offset in mild weather. If the ambient building temperatures are too warm in the mild weather,
decrease the Water Offset. If the ambient building temperatures are too cold in the 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 temperatures.
In radiant heat applications, change the Offset 1°F or 2°F for every 1°F you wish to change the building temperature.
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--- MINIMUM WATER TEMP ----
70 F
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MINIMUM WATER TEMP
Adjustable from 70ºF/21ºC to 180ºF/82ºC Default: 140ºF/ 60ºC
Button: MENU/Set Point/Offset/Outdoor Cutoff/Minimum Water Temp in Reset only
• The Minimum Water Temperature must be set to the boiler manufacturer’s specification.
The BMC will calculate the Set Point based on the Outdoor temperature (OD), the Reset
Ratio, and the Offset value. The BMC will control all boilers modulation to
hold either the Set Point temperature, or the Minimum Water Temperature, whichever is higher.
• The Minimum Water Temperature must be at least 20°F lower than the Maximum Temperature (See next setting).
MAXIMUM WATER TEMP
Adjustable 90ºF/21ºC - 240ºF/116ºC Default: 200ºF/93ºC
Button: MENU/Set Point/Offset/..../Maximum Water Temperature in Reset only
• This is the highest temperature heating water the BMC will circulate through the heating
system. It is available in Reset mode only.
• When using a radiation system, it should be set according to the tubing or floor
manufacturer’s specification.
• The Maximum Temperature must be at least 20°F higher than the Minimum Temperature
(See previous setting).
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--- MAXIMUM WATER TEMP ----
240 F
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