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Electric heating element
Electric resistance type heaters
generally require no normal
periodic maintenance when
unit air filters are changed
properly. The operation and
service life may be affected by
other conditions and equipment
in the system. The two most
important operating conditions
for an electric heater are proper
airflow and proper supply
voltage. High supply voltage
and/or poorly distributed or
insufficient airflow over the
heater will result in the element
overheating. This condition
may result in the heater cycling
on the primary automatic
high limit thermal cutout. If
the temperature becomes too
high, the secondary high limit
thermal cutout may be activated,
breaking the circuit and leaving
the unit non-operational.
The primary automatic thermal
cutout will reset automatically
after the heater has cooled
down, allowing the unit to run
again without intervening.
The secondary thermal cutout
is a safety device only, is
not intended for continuous
operation and will need to be
replaced before the unit will
operate again. With proper unit
application and operation, the
primary high limit thermal cutout
will not operate. This device
only operates when there is a
problem and ANY condition that
causes the high limit cutout to
operate MUST be corrected
immediately. High supply voltage
also causes excessive amperage
draw and may trip the circuit
breaker or blow the fuses on the
incoming power supply.
After proper airflow and supply
power are verified, regular filter
maintenance is important to
provide clean air over the heater.
A dirty filter will inhibit the proper
airflow, leading to high temperature
situations. Improper filtration will also
lead to dirt being deposited on the
heating element, causing hot spots
and eventual element burn through.
These hot spots will generally not
be enough to cause the high limit
switches to trip and may not be
evident until the element actually
fails. Dirt deposited on the element
may also cause unwanted odors in
the air-conditioned space as the
foreign material is burned off.
Electrical wiring & controls
Electrical operation of each unit is
determined by the components and
wiring of the unit. This may vary
from unit to unit. Refer to the wiring
diagram located in a zip-lock plastic
bag in the electrical control box of
each unit for the actual type and
number of controls provided on each
unit.
The integrity of all electrical
connections should be verified at
least twice during the first year of
operation. Afterwards, all controls
should be inspected regularly for
proper operation. Some components
may experience erratic operation or
failure due to age. Thermostats may
become clogged with dust/lint, and
should be periodically inspected and
cleaned to provide reliable operation.
When replacing any electrical
components such as fuses,
contactors, relays or transformers,
use only the exact type, size and
voltage component as furnished
from the factory. Any deviation from
this could result in personnel injury
or damage to the unit and will void
the manufacturer’s warranty. All
repair work should be done in such
a way as to maintain the equipment
in compliance with governing local
and national codes, ordinances and
safety testing agency listings.
Valves and piping
No formal maintenance is
required on the valve package
components other than a visual
inspection for possible leaks
during normal periodic unit
maintenance. Strainers, when
included, should be checked
regularly for build-up and rinsed
as needed. In the event that a
valve should need replacement,
the same precautions taken
during the initial installation
to protect the valve package
from excessive heat should
be implemented during
replacement.
Throwaway filters
These types of filters should
be replaced on a regular basis.
The time interval between
replacement is dependent upon
the environment in which the
unit is operating and should
be established based on
regular inspection of the filter.
Record the time interval in the
maintenance log for future
reference. Refer to the product
catalog for the recommended
filter size. If the replacement
filters are not purchased from
the factory, the same type and
size filters should be obtained.
Pleated media or extended
surface filters should not be
used without consent from
the factory due to the high air
pressure drops associated with
these types of filters, negatively
affecting unit performance.
Normal operation/maintenance
