Preferred JC-22D2 User Manual

SDI-JC-22D2 rev. 11-1-21 page 5 of 22
Control Types, Control Options, and Actuators
The JC-22D2 allows field selection of: control types, output/actuator type etc…. The field wiring and the required auxiliary
equipment changes based on the selections made. Please read the following descriptions.
Control Types: Floating vs. PID

Floating control has (2) tuning adjustments: Deadband (DB) and Proportional Band (PB). PB slows down the actuator/VSD
rate of change (speed) as the Draft approaches the Setpoint, which makes overshoot and oscillation less likely. This makes
it easier to tune and provides very good control.

PID control has (3) tuning adjustments: Deadband (DB), Proportional Band (PB), and Integral (I) (also called “Reset”).
Instrument Technicians are typically more familiar with this type of controller tuning and can tune for tight Draft control.
However, burner technicians who are less familiar with PID tuning can improperly tune the controller and inadvertently
cause overshoot and Draft control oscillation.
Command Types: Triac vs. mA

Triac output is used with a 3 wire AC reversible actuator with Open, Close, Neutral terminals. The JC-22D2 internal solid
state Triacs energize the Open or Close outputs. Some Triac actuators have a position feedback potentiometer, such as:
models R-AL-2A, SM-xx, UM-xxx, some do not: models: PL-2A-xxx. Triac actuators without a position feedback pot
can not be used with some features, see the compatibility chart below.

4-20 mA or 0-20 mA output can be used with actuators that have with built-in “positioners” (electric or pneumatic) that move
the actuator to a position proportional to the mA command. mA outputs can also command an ID Fan VSD.
External resistors (available separately) can be used to convert the mA signal into a wide variety of DC voltage signals:
1-5V, 2-10V, 0-5V, 0-10V. The Adjustable Starting Position option can not be used with a mA Command actuator or VSD.
Firing Rate Feedforward

During a burner firing rate change, Feedforward control starts to move the damper (or VSD) before the change in burner air
flow causes the draft to deviate from the Setpoint. This is very beneficial for low NOx burners that require tight FGR and air
flow control in order to prevent combustion issues. The JC-22D2 has a Feedforward Proportional Band tuning adjustment
and has 2 “firing rates versus damper position” Feedforward curves for dual fuel burners. See the compatibility chart below.

A burner Firing Rate signal is required: 4-20mA, 0-5V, 0-10V, or Potentiometer. The Model SPS (Shaft Position Sensor)
includes linkage for jackshaft style burners
Adjustable Start Position Option

Installations with extremely tall stacks, or with an oversized ID fan, can create an excessively negative draft if the
Draft Damper wide open during light-off. This can cause nuisance pilot flame failures. The default JC-22D2 sequence
positions the damper wide open for Purge, Ignition, and Main Flame Trial.

The Adj. Start Position option positions the damper wide open for Purge and then moves to a partially closed position after
Purge completes. When the damper reaches this position, if the measured draft not sufficiently negative, the damper will jog
open until the Draft is more negative that the User set Adj. Start Draft Setpoint. When the Draft is acceptable, the
JC-22D2 Adj Start Relay Output energizes.

NOTE: This Option should NOT be used unless absolutely required by the site conditions. This Option requires a second
damper proving switch to be used as a Burner Flame Safeguard Ignition Interlock, see page 11 wiring diagram.
Configuration Compatibility Chart
Actuator Compatible Control Type and Options
Command Type Triac Feedback Control Type Feedforward Adj. Start Position
Triac No Floating No No
Triac Yes PID or Floating Yes* Yes**
4-20 or 0-20 mA
damper or VSD
N/A PID or Floating Yes* No
*The controller must have a firing rate input to use the Feed-forward option.
**The controller must have either a firing rate input or a purge/low fire DIN indication from the
FSG to use the Adjustable Start option.

Preferred JC-22D2 Specifications

General

Brand	Preferred
Model	JC-22D2
Category	Controller
Language	English