Dunkirk Q95M-200 Modulating Condensing Boiler - Manual (Page 5)

5
Control module provides freeze-up protection when boiler
water temperature drops below 45° F:
• Below 45° F, boiler circulator operates constantly.
• Below 37° F, boiler operates at low fire.
• Boiler and circulator turn off if boiler water temperature
rises above 50° F.
This boiler control feature does not eliminate possibility
of freezing. Installation must use recognized design,
installation and maintenance practice to prevent freeze
potential for boiler and system.
Supply Temperature Boost
• Outdoor reset operation (factory supplied, field installed
outdoor sensor connected), boiler control automatically
increases target outlet water temperature if call for
heat exceeds 10 minutes.
• At each 10 minutes of continuous call for heat, control
module increases target temperature by 18°F. Module
continues increasing target temperature until it reaches
value set in Parameter 4.
• When call for heat ends while target temperature is
“boosted,” target temperature drops about 2°F for each
minute thermostat is open.
Purpose of “Boosting”: If target temperature is too
low, control “boosts” target temperature until supply water
meets system needs.
Outdoor Reset Operation
Target temperature with outdoor reset: All boilers ship with
outdoor temperature sensor. When sensor is installed (low
voltage terminal strip terminals A1 and A2), boiler control
regulates target outlet water temperature based on outside
temperature.
Set temperature curve by setting Parameter 4 to:
• ODT (outdoor design temperature for the area).
• ODT of 0°F or lower, set Parameter 4 to desired supply
temperature at ODT.
• ODT above 0°F, set Parameter 4 to desired system
temperature when outdoor temperature is 0°F.
Reset curve: See reset curve graph, shows how boiler
control calculates target temperature.
• Outdoor temperature at or below 0°F, target
temperature equals Parameter 4 and never higher.
• Outdoor temperature above 0°F, target temperature
is reduced on a curve that would result in 60°F supply
temperature at 70°F outdoor temperature.
Summer/winter switch option: Install summer/winter
switch, if desired, to disable boiler (space heating)
circulator during non-heating months. Connect switch
across outdoor sensor terminals. When switch closes, boiler
circulator is disabled and boiler operates only on call for
DHW heating.
DHW Operation (option)
Control allows connection of DHW aquastat to low voltage
terminal strip terminals DHW T1 and DHW T2. When
DHW aquastat calls for heat, module shuts down boiler
circulator activated DHW circulator and immediately sets
target outlet water temperature to 180°F. This provides
automatic priority heat allocation to indirect water heater
for maximum response and recovery. DHW circulator
continues for 30.6 seconds after heating cycle to deliver
heat.
3 - OPERATING INFORMATION
Target Outlet T
emperature, °F
Outside Temperature, °F
Outdoor Reset Target Temperature
210
50
70 60 50 40 30 20 10 0 -10 -20
70
90
110
130
150
170
160
190
120
Parameter 4 = 190°F
Parameter 4 = 150°F
Parameter 4 = 170°F
Reset Curve Calculations
Reset Curve Calculations
Target Outlet T
emperature, °F
Outside Temperature, °F
Default Reset Curve
Outdoor Reset Target Temperature
210
50
70 60 50 40 30 20 10 0 -10 -20
70
90
110
130
150
170
160
190
180
120
Parameter 7 = 60°F
Parameter 4 = 180°F
Parameter 6 = 0°F
Default Reset Curve