DRAFT CONTROLLER Model JC-22D Uncontrolled stack draft can cause burner instability, unreliable ignition, and affect fuel-air ratio control repeatability. Burner manufacturers typically recommend draft controls be installed in applications where: • Stack height exceeds 75 feet • Multiple furnaces are connected to a single stack JC-22D “Floating” Draft Control Mode • Direct Field Replacement for existing JC-20F11AR2 and similar units • Compatible with existing electric draft actuator, does not require feedback pots • Uses proportional control to direct the damper open or closed until the draft returns to setpoint. JC-22D “Precise” Draft Control Mode • Precise PID control • “GAP” PID Draft Control uses a dual gain strategy (ie.: lower gain near setpoint, higher gain farther away from setpoint) to allow precise draft control without hunting due to draft pulsations. • Firing rate feedforward allows the controller to instantly respond to changes in firing rate demand without waiting for the outlet pressure to deviate from the acceptable range. This is especially important in Induced Flue Gas Recirculation (IFGR) applications. JC-22D Draft Controller • Adjustable Start Position directs the outlet damper to 100% for purge and then closes the damper to a predetermined position for light-off. Boilers with very tall stacks, oversized ID fans, or wide turndown Low NOx burners may not be able to light-off with the outlet damper wide open. Automatic Draft Sequence • Damper positioned for purge, light-off, post-purge and burner shutdown. To prevent pressurizing the boiler during startup, the draft damper opens immediately, and the burner fan start is delayed 0 - 30 seconds (adjustable). The damper is closed when the boiler is off-line to minimize energy waste. Low Draft Alarm Message and Contact Automatic Draft Control Increases Boiler Efficiency • Reducing the air infiltration into the furnace reduces heat Draft Control General Arrangement lost up the stack. Uncontrolled boiler draft results in a *Not required for “floating” point draft control applications more negative boiler pressure and therefore more cold air being drawn into the boiler • Maintaining a stable and optimum draft despite changes Description in ambient air temperature, wind velocities, firing rates, The JC-22D Draft Monitor and Controller is a microprocessor- and flue pass sooting conditions allows the burner control based draft controller, indicating instrument, and alarm systems to operate with less excess air. At a given F.D. monitor. The JC-22D directly accepts a 4-20 mADC draft fan inlet damper position, the air flow through the burner transmitter signal, 120 VAC flame safeguard interface, will change as boiler draft changes. and outputs a solid state switching (triac) or 4-20 mADC outlet damper actuator control signal. Draft is continuously displayed using a highly visible backlit LCD display. An intuitive bargraph display and alarm message provide clear boiler draft status. All adjustments can be made directly from the faceplate of the instrument by scrolling through user friendly, English language menus. The outlet Preferred Manufacturing  203.743.6741 •  203.798.7313 www.preferred-mfg.com DRAFT CONTROLLER Model JC-22D damper may be controlled in “Auto” or “Manual” mode and Ordering Information will automatically sequence through the purge, light-off, To order a “Floating” Draft Control System, specify post-purge and burner shutdown modes in response to the following: flame safeguard system inputs. The JC-22D automatically 1) Specify Model JC-22D Draft Controller with Model positions the outlet damper according to burner operation JC-XMTR Draft Range Transmitter Assembly based on either the field selectable “Floating” or “Precise Draft” Control modes. 2) Specify DM-2 Electric Rotary Actuator or PL-2 Electric Linear Actuator Specifications Panel 3) Alternately, Specify Model JC-22D Draft Controller Power Supply: 120 VAC, +/- 15%, 50/60Hz, 15 VA and Model E-Link Draft Damper Assembly Case Size: 8" H x 3.5" W x 7.5" D Enclosure Type: NEMA 4 faceplate Ambient Temp.: +32° to 122° F To order a “Precise” Draft Control System, specify Displays: High Contrast LCD Display the following: 4" high, 0.5% Resolution Bargraph 1) Specify Model JC-22D Draft Controller with Model Bargraph Range: -1.00 to +1.00" W.C. JC-XMTR Draft Range Transmitter Assembly Alarm Setpoints: One (1) adjustable contact with adjustable time delay 2) Specify SM Electric Rotary Actuator Triac or R-AL-2- Inputs 3-P1-4-S2-0 Electric Linear Actuator (4-20 mA) Draft Input: 4-20 mADC digital filtered Firing Rate Input: 300 ohm (minimum) or 4-20 3) Alternately, Specify Model JC-22D Draft Controller mADC and Model E-Link Draft Damper Assembly Discrete Input: Five, Optically isolated 120 VDC, 10 mA load 4) Specify Model SPS Shaft Position Sensor Actuator Feedback: 300 ohm min feedback pot (when required) (required for GAP PID Control Mode) Outputs Relay Outputs: Three SPDT Relays 10 A Resistive, 8 FLA, ½ HP, 120 VAC Actuator Outputs: One Triac pair, 2 FLA/24-120 VAC or 4-20 mADC Network: 1200 - 38400 Baud; RS485 Modbus, ASCII or RTU C JC-22D Mounting and Clearance Dimensions Preferred Manufacturing  203.743.6741 •  203.798.7313 www.preferred-mfg.com DRAFT CONTROLLER Model JC-22D Suggested Specifications 1. Application 5. Draft Range Transmitter and High Pressure Switch Provide a self contained automatic sequence draft controller for Provide a draft range transmitter and high pressure (low draft) each furnace. The controller shall be microprocessor-based and switch with time delay relay. Both shall be supplied with field suitable for flush, panel mounting. Provide a field mountable 4-20 mountable, dust-tight, splash-proof enclosures. A single draft mADC pressure draft transmitter for measuring boiler outlet draft. connection shall be piped to -1" W.C. to +1" W.C. 4-20 mADC Provide a high flue gas pressure (low draft) switch with 5 second transmitter and an independent low draft switch. The low draft delay for use in the Flame Safeguard Limit Circuit. switch setpoint shall be field adjustable from +0.15" W.C. to +4.0" 2. Draft Controller W.C. The low draft switch shall be mounted and wired to a pilot The Controller shall continuously indicate furnace draft, draft light so as to illuminate when the low draft switch activates and to setpoint and alarm setpoint on a highly visible backlit LCD display. a 5 second time delay relay so as to provide an isolated “Low Draft The control shall provide both automatic and manual damper Cut-Out”, 10 A contact for use in the Flame Safeguard Limit Circuit. control. Provide an integral or separate 4", 0.5% resolution The time delay feature helps avoid nuisance burner shutdowns (minimum) bargraph display in engineering units with visual due to momentary draft fluctuations. alarm indication. Provide a “High Boiler Pressure” alarm, “Alarm 6. Draft Damper Actuator (when required) Silence” pushbutton and one 10 A alarm relay output. The housing Provide an electric Draft Damper Actuator for each furnace. The shall be panel mountable, fully gasketed with NEMA 4 front face. actuator shall have adequate power to automatically position the All adjustments shall be made from the front panel display in damper and shall be suitable for control by the Draft Controller. engineering units. The controller shall include setup menus for The actuator shall be totally enclosed in a dust-tight housing; have easy operation, tuning and troubleshooting from the Controller integral, snap-action, travel limit and open proving switches, be faceplate. No external configuration tools shall be required. capable of being stopped, started, or instantly reversed without 3. Automatic Draft Sequence loss of power or overloading. A double ended output shaft shall The controller shall include an automatic draft sequence as follows: have an integral brake for precise positioning without backlash during burner “off” periods the draft control damper shall remain and rotate 90º in 30 seconds. When the precise draft control closed to hold residual heat within the boiler. On a call for burner mode is selected, the actuator shall include an electrically isolated operation the outlet damper shall be driven open for pre-purge. feedback potentiometer. To prevent pressurizing the boiler, the burner fan shall start after a 7. Draft Damper Assembly - Model E-Link (when required) field adjustable time delay after starting to open the draft damper. Provide a factory assembled stack damper assembly for each The damper shall remain open for burner light-off. When the fuel furnace. The draft damper shall be a dual opposed blade design, valve opens, the draft control damper shall be released from the have 24" inside diameter [select from 12", 16", 20" or 24" diameter open position and modulate as required by the draft setpoint. to match boiler outlet, consult factory for larger sizes], constructed During normal burner shut-down the damper shall be driven open of 10 gauge rolled steel. Non-opposed blade damper designs are during the post-purge period and then closed when the fan stops. not acceptable. Factory mount the draft damper actuator, draft Abnormal burner shut-down (safety lock-out of flame safeguard range transmitter and time delayed, high pressure (low draft) control) shall cause the damper to drive open where it shall cut-out assemblies (described in the above paragraphs) on the remain until the flame safeguard system is reset. The controller damper assembly. The damper actuator and damper assembly shall interconnect with the flame safeguard system directly using shall be stroked at the factory to ensure proper alignment. “Shipped 120 VAC signals. Loose” components will not be accepted. 4. Draft Damper Modulation 8. Communication When the precise draft control mode is required, the controller The Instrument shall include a RS485 Modbus network interface shall provide boiler outlet damper modulating control based on to communicate to a future Data Acquisition System (DAS) or characterizable firing rate feed-forward signal to assure stable draft Building Automation System (BAS). during load changes and “GAP” PID Draft Control for improved 9. Quality Assurance stability. Provide a Model SPS firing rate feedback potentiometer The Instrument shall be manufactured and labeled in accordance as manufactured by Preferred Instruments, Danbury, CT, or firing with UL508 (CSA C22.2 #14 for use in Canada). Inspection and rate output from the firing rate controller. The controller shall be labeling shall be supervised by UL or other OSHA approved capable of establishing an adjustable position for burner light- Nationally Recognized Test Lab (NRTL). The draft control off. Each fuel shall have an independent light-off position. The system shall be a Preferred Instruments, Danbury, CT, Model controller shall not close the light-off contact output unless the JC-22D Draft Controller with Model JC-22XMTR Draft Range damper is above the proper position and the pressure is below Transmitter Assembly or JC-22D Draft Controller and E-Link the starting draft setpoint. Alternately, the controller shall be field Draft Damper Assembly and Model SPS Shaft Position Sensor selectable to provide “Floating” draft control. When “Floating” draft (when required). control is selected, the controller shall provide proportional control of the boiler outlet damper to maintain boiler draft at setpoint using a 24 VAC, Triac positioning output. Preferred Manufacturing  203.743.6741 •  203.798.7313 www.preferred-mfg.com