Enviro VHA, Installation Operation & Maintenance

Page: 42 / 80

ENVIRO-TEC
42
FORM ET115.24-NOM4 (819) SECTION 3 - NORMAL OPERATION & PERIODIC MAINTENANCE
SECTION 3 - NORMAL OPERATION & PERIODIC MAINTENANCE
GENERAL
Each unit on a job will have its own unique operating
environment and conditions that may dictate mainte-
nance schedule for that unit that is different form other
equipment on the job. A formal schedule of regular
maintenance and an individual unit log should be es-
tablished and maintained. This will help to achieve the
maximum performance and service life of each unit on
the job.
Information regarding safety precautions contained in
the preface at the beginning of this manual should be
followed during any service and maintenance opera-
tions.
For more detailed information concerning service op-
erations, consult your Sales Representative or the Fac-
tory.
MOTOR/BLOWER ASSEMBLY
The type of fan operation is determined by the control
components and their method of wiring, and may vary
from unit to unit. Refer to the wiring diagram for each
unit for that unit’s individual operating characteristics.
All motors have internal automatic reset thermal over-
loads.
Should the assembly require more extensive service,
the motor/blower assembly may be removed from the
unit to facilitate such operations as motor or blower
wheel/housing replacement, etc. The motor/ blower as-
sembly is supplied on a slide-out rail system
( see Fig-
ure 30 on page 42). To remove, loosen the two lock
nuts at the rack front and slide the blower assembly out.
Disconnect the motor electrical plug to fully remove
the assembly from the unit. To reinstall the blower, re-
peat the removal sequence in reverse order. The rear of
the blower must catch on the support bracket supplied.
Dirt and dust should not be allowed to accumulate on
the blower wheel or housing. This can result in an un-
balanced blower wheel condition that can damage a
blower wheel or motor. The wheel and housing may
be cleaned periodically using a vacuum cleaner and a
brush taking care not to dislodge the factory balancing
weights on the blower wheel blades.
SHIELD
BLOWER
OPTIONAL
TYP
(4) PLCS
TYP
(2) PLCS
FIGURE 30 - MOTOR/BLOWER ASSEMBLY
COIL
Coils may be cleaned by brushing the entering air
face between fins with a soft brush. Brushing should
be followed by cleaning with a vacuum cleaner. If a
compressed air source is available, the coil may also
be cleaned by blowing air through the coil fins from
the leaving air face. Vacuuming should again follow
this procedure. Units provided with the proper type of
air filters, replaced regularly, will still require periodic
coil cleaning.
ELECTRIC RESISTANCE HEATER ASSEMBLY
Electric resistance heaters typically require no normal
periodic maintenance when unit air filters are changed
properly. The two most important operating conditions
for an electric heater are proper airflow and proper sup-
ply voltage. High supply voltage and/or poorly distrib-
uted or insufficient airflow over the element will result
in element overheating. This condition may result in the
heater cycling on the high limit thermal cutout. Open
coil strip heaters have an automatic reset switch with
a back-up high limit thermal switch. Automatic reset
switches are as the name implies; they reset automati-
cally after the heater has cooled sufficiently. High limit
thermal switches must be replaced once the circuit has
been broken. The high limit thermal cutout device is a
safety device only and is not intended for continuous
operation. With proper unit application and operation,
the high limit thermal cutout will not deactivate the
heater. This device only operates when some problem
exists and ANY condition that causes high limit cutout
LD13879