Electric Heaters - Carrier AERO 39MN Installation, Start-Up And Service Instructions Manual

KEY 2) to save the configuration and return to the
Clock Set menu.
7. Use the UP or DOWN keys to highlight DATE FOR-
MAT and press SEL (SOFT KEY 2). Use the UP or
DOWN keys to change the parameter setting. Press OK
(SOFT KEY 2) to save the configuration and return to
the Clock Set menu.
8. Press EXIT (SOFT KEY 1) twice to return to the main
menu.
I/O Settings Mode — The I/O Settings mode is used for
viewing and editing the I/O settings.
To configure the I/O settings, perform the following
procedure:
1. Select MENU (SOFT KEY 2). The Main menu will be
displayed.
2. Use the UP or DOWN keys to highlight I/O SETTINGS
on the display screen and press ENTER (SOFT KEY 2).
The I/O Settings parameter list will be displayed.
3. Use the UP or DOWN keys to highlight the desired I/O
setting and press SEL (SOFT KEY 2).
4. Use the UP or DOWN keys to select the parameter to
view. Press OK (SOFT KEY 2).
5. Use the UP or DOWN keys to change the parameter set-
ting. Press SAVE (SOFT KEY 2) to save the configura-
tion. Press CANCEL (SOFT KEY 1) to keep the previ-
ous value. Any modifications that are not saved will not
be changed.
6. Press EXIT (SOFT KEY 1) twice to return to the main
menu.
Electric heaters are factory installed.
Electric Heaters —
If circumstances require field installation of an electric heat-
er, it can only be installed in a factory-supplied EHS (Electric
Heat section). Installation of electric heat in a section other
than an EHS section will void the UL listing of the product.
1. Identify ALL electrical power supplies serving the unit,
lock off and tag each before working on the unit.
2. Locate the electric heat section mounted on the unit and
remove the protective shipping cover.
3. Identify the electric heater and verify the heater matches
the unit. Unit hand and heater hand must also agree.
4. Properly sized power wiring and control wiring entry
holes are provided in the upstream sidewall of the heater
control box.
For outdoor unit sizes 36-110 only, a narrow, fixed up-
stream panel is provided for electrical power entry from
the outside. Power may also enter the unit from below,
penetrating the floor of the unit. Carefully seal all en-
tries, weathertight where necessary. Control wiring may
enter the same way as electrical wiring.
Take future service requirements into account when lo-
cating field power entry holes in the unit casing.
5. Sleeve these holes and seal around the conduit to pre-
serve the integrity of the casing. In some cases, it might
be preferable for the power to actually enter the cabinet
through an adjacent section, or enter the control box
from another angle, which is acceptable.
6. If the original holes are not used, they must be appropri-
ately plugged.
7. Insert the electric heater into the section (the heater ele-
ment rack will be located along the leaving air side of
the section).
NOTE: If the heater must be hoisted into position, once the
top panel has been removed to a safe place, the horizontal top
rail may be removed by carefully removing the flat corner
plug from the end corner pieces and extracting the screw
visible within the exposed cavity. (Do not mix these screws
with others, as they are specific for this location.) The cor-
ners may then be separated, lifting the rail and corner seg-
ments away from the unit at approximately a 45-degree
angle, taking care not to damage the double bulb seal.
8. The heater has lifting hook openings on each end. When
the heater is within 3 in. of its final position, reinstall the
crossrail, with the box-seal facing down, and panel seal
toward the top.
9. Secure the heater to the section posts and rails with the
furnished screws, drawing it the last
sealed position against the framework, by alternately
cross tightening the screws. The opposite end of the
heater rests on lateral spacers provided on the floor pan-
el, and is retained by a screw through an angle clip on
the last one or by an upright corner flange.
10. Replace the top panel, and proceed to complete the wir-
ing in accord with all applicable codes and ordinances.
The wiring diagram is fastened inside the control box,
with a spare, loose copy provided as a convenience for
maintenance manual preparation. Do not mix the wiring
diagrams, as they are specific for each unit.
11. Connect power and control wiring according to the wir-
ing diagram supplied (see Fig. 90-92 for typical wiring
details).
CONNECT POWER AND CONTROL WIRES —
wiring schematic is located on control box panel. Verify min-
imum airflow requirement (minimum coil face velocity, fpm)
will be met, especially on applications where variable air vol-
ume is supplied.
Use copper power supply wires rated for 75 C minimum.
On 250 v or greater applications, use 600 v rated wiring. Size
wires to carry 125% of current load on each set of terminals.
Use the following formulas as required:
Single-phase line current =
Three-phase line current =
Note that if the heater is rated at 50 kW (or more) and is
controlled by a cycling device such as a multi-stage thermo-
stat, or a step controller, conductors may be sized at 100% of
load amperes (see Table 30) per NEC Section 424-22. Heater
construction and application information are based upon
Space Heating Standard UL No. 1096 and the requirements
of the NEC. Installer is responsible for observing local code
requirements.
Install a disconnect switch or main circuit breaker in ac-
cordance with NEC and other applicable codes. Locate so
that it is easily accessible and within sight of heater control
box (per NEC Article 424-19 and 424-65).
Weatherproof junction boxes have no knockouts for wire
entrance. Provide knockouts for all wiring using field-
supplied grommets of correct size and type of conduit as
required.
Where field-supplied thermostats are used, isolate circuits
to prevent possible interconnection of control circuit wiring.
Where field-supplied step controller is used, connect steps
to terminals as marked on wiring schematic. When connect-
ing multi-stage heaters, wire stage no. 1 so that it is first stage
on, last stage off.
Provide sufficient clearance for convection cooling of
heaters with solid-state controllers. Provide at least 5-in. of
free air space above and below cooling fins extending from
heater terminal box. Be sure to connect interlock terminals F1
and F2 to auxiliary contacts on fan starter.
103
3 / in. into final
8
Heater
(kW per set of terminals) (1000)
voltage
(kW per set of terminals) (1000)
(voltage) (1.73)