Thermolec Mini Make Up Air User Manual
INSTALLATION
INSTRUCTIONS
FOR MINI MAKE-UP AIR
MODEL FER
May 2012
VERSION 1.3
Please read instructions carefully before installation.
This unit is a complete fresh air make-up package with an integrated damper system, washable fi lter and fan
with adjustable speed control which allows an easy setup with a minimum of connections. Only one power
connection is required to power the entire unit. Please follow the wiring diagram included under the cover for
specifi c electrical wiring. Thermolec FER mini make up air units are available in sizes up to 20 kW of heat at
voltages ranging from 120V single phase to 600V three phase. Collar sizes range from 6” to 12” with fans ca-
pable of up to 600 CFM. Mini make up air models are specifi ed as follows: FER-collar-kW-voltage/phase, e.g.
a 20kW, 240V (single phase) unit with a 12” collar would be FER-12-20-240/1. For small 6” applications up to
3kW at 240/1 take a look at our THERMO-X-AIR units which include a room controller to control the operation
mode of the integrated fan.
Mechanical installation
Thermolec FER heaters are designed to be installed for horizontal airfl ow only (fi g. 1). DO NOT install unit
vertically (fi g. 2). This unit is equipped with thermal cutouts on both the top and bottom of the unit which al-
lows it to simply be rotated 180º to change the direction of airflow with no modifications to the fan or wiring, as
seen in fig. 3. The direction of airflow from the fan itself is fixed and cannot be reversed. Before mounting the
unit, determine the direction of airflow required and rotate the unit accordingly.
NOTE: This unit is designed to preheat fresh air and not reheat ambient air.
Reversable Airflow
Thermal cutout
Controls
Air
O.K.
fig. 1
Thermal cutout
fig. 2
fig. 3
Controls
Air
Inlet
Inlet
For proper airflow, a minimum distance between the unit and any elbow must be observed. This distance
increases as the unit size increases. To determine the proper distance, multiply the collar size of the unit by a
factor of 1.5. For example a unit with a 12” collar would require elbows to be installed at a distance of not less
than 18” (fig. 4). Use round insulated duct for the inlet connection and uninsulated for the outlet while minimizing the use of elbows. When taking air directly from outside, install the inlet duct at an incline such that condensation or melted snow will not flow into the heater.
fig. 4
FER
D” x 1.5 D” x 1.5
Attach the unit to a suitable support allowing a minimum 1/2” clearance above the heater. Always install the
unit such that there is sufficient space to remove the cover and the damper assembly if necessary as well as to
remove washable filter for cleaning (fig. 5). The hanger brackets provided (fig. 6) are designed to be used with
threaded rods (not included). Springs may be added to the rods as an option to reduce vibration (not included).
fig. 5
Fan
Heater
Damper
Filter
Rod
fig. 6
Duct sensor
Bracket
Cover opens
this way
Air Outlet
Controls
Air
Inlet
Bolt
Lock washer
Flat washer
Use supplied Current Sensor
or On/Off contact to start unit.
The minimum amount of air required (in cubic feet per minute) to operate
CFM
the unit is 30 CFM per kW. A 10 kW unit will require 300 CFM. The fan is
adjusted with the speed control knob located inside the control panel.
Rotating the knob clockwise from the off position starts the fan at maximum
speed and the speed reduces as the knob continues in a clockwise motion.
Actual CFM is based on the static pressure in the duct, for best results
measure the static pressure and then refer to the fan performance chart at
the end of the manual for more detail.
When there is a demand from the current sensor (or a dry contact), the
MAX
OFF
MIN
electronic controller will turn on the fan and start heating. The duct sensor
must be installed in the duct downstream from the mini make up air unit for proper operation. Adjust the blue
square potentiometer on the D23-TF electronic controller with a small screwdriver to control the output temperature. Use the chart below the potentiometer to convert the temperature from Celsius to Fahrenheit.
10°C 15
+-
+-
C2
10°C 15
30°C 25
°C 0 5 10 15 20 25 30 35
°F 32 41 50 59 68 77 86 95
A
C3 FR
COM
24
VAC
GD/OA
30°C 25
°C 0 5 10 15 20 25 30 35
°F 32 41 50 59 68 77 86 95
Duct
Sensor
SSR1
D23-TF
SST1L1
DF12W
The duct sensor must be wired to the ‘S’ ‘S’ terminals on the D23-TF. The controller monitors the outlet temperature and alerts of abnormal conditions with a fl ashing light (W) that can be seen on the D23-TF controller,
see Table A below. In the event of a heater failure, such as a tripped manual cutout, the controller will shutdown
the unit to avoid circulating unheated outside air and the warning LED will start fl ashing. If for some reason the
output temperature is too hot, to avoid a potentially dangerous situation, the controller will also shutdown the
unit and fl ash the warning LED accordingly.
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