Steffes 6140 - Manual (Page 9)

Optional
Accessories
SCR CONTROLLER
The Steffes SCR (Solid State Relay Panel) is an optional control device used with
the Steffes ThermElect (8100 and 9100 Series) and Comfort Plus Commercial
(6100 and 7100 Series) Heating Systems. It utilizes SCR technology to enable more
precise balancing of a building’s overall electric load by varying the amount of total
element input that can be energized in a Steffes furnace at any given time in relation
to the maximum allowable building load. The Steffes SCR optimizes a building’s
power quality and control.
The SCR Controller can only accept input signals from the Steffes furnace but it
can respond to all types of control inputs to include 4 – 20 Milliamp, 1 – 5 Volt DC,
electric meter pulsing, Bacnet or any building energy management system. With the
4 – 20mA or 1 – 5 volt DC signals, the SCR will provide an output directly propor-
tional to the input signal. 4mA signal produces 0% output while 20mA signal products 100% output. With the utility
pulse meter input, the SCR output percentage will automatically adjust to maintain a total maximum system load as
dictated by the furnace’s set-up. With a Bacnet, the furnace can be commanded to varying input levels remotely.
CONTROL CIRCUIT STEP-DOWN TRANSFORMER
The internal controls and motors of all Comfort Plus Forced Air Commercial systems operate at 240 volts (two
wire). In systems with 277/480 or 347/600 volt element circuits, a transformer must be installed per the installation
instructions to supply this voltage to the system’s controls. This transformer can be purchased as an optional device
from Steffes Corporation or sourced from your local electrical supply outlet. See the matrix below for proper sizing.
EXTERNAL DUCT SENSOR
The optional external duct sensor (Order Item #1041536) provides the ability to monitor the duct temperature at an
area beyond fresh air makeup and/or beyond other devices and regulate the discharge air temperature accordingly.
The duct sensor feature is enabled if the 4 bit is set in Location 53 (L053). Once enabled, the Comfort Plus Com-
mercial system monitors temperature at both the duct sensor and the output sensor during Y, W/Aux, or E calls
from the thermostat.
If there is a Y and a G call from the thermostat, the system operates the core blowers at the required speed to
maintain the minimum output temperature as set in Location 48 (L048) at the duct sensor. If there is only one call
from Y, W/Aux, or E, then the system will operate the core blowers at the required speed to maintain the maximum
output temperature as set in Location 49 (L049) at the duct sensor. The system is set to turn off the core blowers if
the output temperature at the output sensor exceeds 150 degrees Fahrenheit.
RETURN AIR PLENUM
An optional factory built return air plenum is available for the Comfort Plus Commercial system(Order Item
#1041570). This plenum incorporates a tray for placement of a heating/cooling coil which must get set in the return
ductwork when interfaced to a heat pump. The return air plenum connects directly to the system for either a right-
to-left or left-to-right airflow pattern.
DOWN FLOW KIT
The Comfort Plus Commercial system is designed for upflow supply air discharge. In applications where downflow
air discharge is desired, Steffes offers a kit that provides the ability to connect the supply air plenum in a manner
that directs the air downward. (Order Item # 1301578). In downflow configuration, the furnace must be installed in
a fashion that allows access to the supply blower’s plenum cover. It is recommended to elevate the furnace a
minimum of 10" to achieve this access. An 18" elevation stand (Order Item #1301585) is available.
Comfort Plus Commercial Optional Accessories
n
2.02
Model
Primary
Voltage
Secondary
Voltage
KVA Hevi Duty Item #
Steffes
Item #
277/480V 480 240 2 HS1F1BS or equal 1017082
347/600V 600 240 2 HS10F2AS or equal 1017080
SCR CONTROLLER
Order Item #1301016