Qmark Open Coil Electric Duct Heaters - Manual (Page 4)

OPERATING
INSTRUCTIONS
1. Ensure that sufficient air flow as marked on the nameplate is
passing through the heater. Air flow should be evenly
distributed across the entire face of the heater. Use air turning
vane at duct elbows and splitter damper at duct branch-offs to
streamline the air flow in the heater. Use suitable air flow
sensing device or interlock the heater with fan. An insufficient
air flow will lead to the opening of the auto-reset thermal cut-
out or damage to the heating elements.
2.. The air temperature should not exceed 27°C (81°F) at the
heater inlet and 66°C (151°F) at the outlet.
3. The heater is protected by a differential pressure switch. To
keep the contact of this switch closed, it is necessary to
maintain a minimum total pressure of 0.07 inches of water for
a constant flow. Unless otherwise specified, all duct heaters
operate horizontally or vertically with the airflow in either
direction. This unique feature allows the contractor maximum
flexibility in installation and avoidance of problems.
4. Manual-reset thermal cut-out is a protection device that is
standard on all heaters. Please check the auto-reset thermal
cut-out BEFORE re-setting the manual thermal cut-out. If any
defect has been detected in the auto-reset thermal cut-out, it
will be necessary to replace it before re-setting the
manual-reset thermal cut-out.
MAINTENANCE
INSTRUCTIONS
It is important to keep this heater clean. Your heater will give you
years of service and comfort with only minimum care. To assure
efficient operation follow the instructions below.
Heaters have been designed to operate long term without
problems. Those responsible for equipment and maintenance
should be aware of the following suggestions.
1. A periodic visual inspection. This precautionary step will help
to keep your installations operating well. Note these eventual
first signs of problems: Accumulation of dust on the heating
elements, signs of overheating on the heater frame, traces of
water or rust on the control box.
2. Two weeks after startup , all electric connections to
contactors should be checked and tightened up. Before each
heating season, check the resistance between the heating
elements and ground. It is also recommended to check the
electrical connections to heating elements, magnetic
contactors, and main power lugs. This inspection is
recommended monthly during the first four months of
operation. After that, two inspections per heating season are
sufficient.
3. Inspect the following checkpoints:
• Check all fuses;
• Check the resistance to ground for each circuit;
• Check the resistance phase to phase for each circuit;
• Check the tightening of connections at all contactors and
heating elements;
• Check all contactors.
4. For off-season maintenance where tubular heating elements
are used, it is strongly recommended that you start the
heating system from time to time. This precaution will prevent
moisture from percolating through the terminal gaskets into the
heating element and accumulating in the insulating
powder. Should a heater be shut off for a long period, we
recommend that you check carefully the resistance to ground
for each circuit. It is important not to power a heater when
too low resistance to ground has been measured. It is also
recommended to pay attention to any other heater operating in
normal conditions. Control components such as step
controllers or modulating valves (SCR) should be maintained
and checked according to respective manufacturers
instructions. Any defective components should be replaced
only with identical original parts.
Maintenance Cleaning Instructions:
(To be performed only by Qualified Service Personnel)
At least annually, the heater should be cleaned and serviced by a
qualified service person to assure safe and efficient operation.
This should include, as necessary, disassembling the heater from
the duct to clean residue from the unit. After completing the
cleaning and servicing, the heater should be fully reassembled
and checked for proper operation.
ALL SERVICING BEYOND SIMPLE CLEANING THAT
REQUIRES DISASSEMBLY SHOULD BE PERFORMED BY
QUALIFIED SERVICE PERSONNEL.
TO REDUCE RISK OF FIRE AND ELECTRIC SHOCK OR
INJURY, DISCONNECT ALL POWER COMING TO HEATER
AT MAIN SERVICE PANEL AND CHECK THAT THE ELEMENT
IS COOL BEFORE SERVICING OR PERFORMING
MAINTENANCE.
THE AIR FLOWING THROUGH THE DUCT WHERE THE
HEATER IS INSTALLED SHALL NOT CONTAIN ANY
COMBUSTIBLE PARTICLES, NOR ANY FLAMMABLE VAPOR
OR GAS.
4