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The complete list of programmable relay output functions follows:
0 = NOT SEL
1 = SYS READY
2 = SYS RUNNING
3 = SYS STARTED
4 = BYPASS SEL
5 = BYPASS RUN
6 = BYPASS FLT
7 = BYP NOT FLT
8 = BYPASS ALRM
9 = DRIVE FAULT
10 = DRV NOT FLT
11 = DRIVE ALARM
12 = OVERRIDE
13 = BYPASS HAND
The Start command can come from the bypass control board ter-
minal block, the ACH550 keypad, the bypass keypad, or serial
communications depending on the operational mode selected. The
System Started relay is ideal for use in damper actuator circuits,
opening the dampers only under those conditions where the sys-
tem is preparing to run the motor. The System Started relay will
de-energize, closing the dampers if the safeties open, the system
faults, or when a Stop command is issued.
Electric Heaters
Electric heaters are factory installed. If circumstances require field
installation of an electric heater, it can only be installed in a facto-
ry-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 that 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 entries,
weather tight where necessary. Control wiring may enter
the same way as electrical wiring.
Take future service requirements into account when locat-
ing field power entry holes in the unit casing.
5. Sleeve these holes and seal around the conduit to preserve
the integrity of the casing. In some cases, it might be pref-
erable 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 ex-
posed cavity. (Do not mix these screws with others, as they are
specific for this location.) The corners may then be separated, lift-
ing the rail and corner segments away from the unit at approxi-
mately a 45-degree angle, taking care not to damage the double
bulb seal.
14 = BYPASS OFF
15 = BYPASS AUTO
16 = COM CTRL
17 = SYS ALARM
18 = BYPASS FLT/ALM
19 = BYPASS OVERLOAD
20 = BYP UNDERLD
21 = PCB OVERTEMP
22 = SYS UNDERLD
23 = SYSTEM FLT
24 = SYS FLT/ALM
25 = SYS EXT CTL
26 = SYS OVERLD
27 = CONTACT FLT
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 the 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 heat-
er rests on lateral spacers provided on the floor panel, 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 wiring
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 mainte-
nance manual preparation. Do not mix the wiring dia-
grams, as they are specific for each unit.
11. Connect power and control wiring according to the wir-
ing diagram supplied (see Fig. 137-139 for typical wiring
details).
CONNECT POWER AND CONTROL WIRES
Heater wiring schematic is located on control box panel. Verify
that minimum airflow requirement (minimum coil face velocity,
fpm) will be met, especially on applications where variable air
volume 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 car-
ry 125% of current load on each set of terminals. Use the follow-
ing formulas as required:
Single-phase line current = (kW per set of terminals) (1000)
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 thermostat, or a step con-
troller, conductors may be sized at 100% of load amperes (see Ta-
ble 39) per NEC Section 424-22. Heater construction and applica-
tion 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 accordance
with NEC and other applicable codes. Locate so that it is easily ac-
cessible 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 pre-
vent possible interconnection of control circuit wiring.
Where field-supplied step controller is used, connect steps to ter-
minals as marked on wiring schematic. When connecting 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.
Each heater has 2 different types of factory-installed thermal cut-
outs for over temperature protection: an automatic reset thermal
cutout for primary protection, and a manual reset thermal cutout to
protect against failure of the primary system. Also provided is an
airflow pressure differential switch to prevent the heater from op-
erating when the fan is not in operation or airflow is restricted or
insufficient. The primary automatic reset cutout is a bi-metal disk-
type cutout. It is wired into the control circuit which operates the
163
/
in. into final
3
8
voltage
(kW per set of terminals) (1000)
(voltage) (1.73)
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