Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) - Manual (Page 38)

MAMM-VHC-IOM-1A (JANUARY 2013) 38
sure the heater is properly interlocked to prevent it from
being energized before the damper is fully open.
3 – Operating Electric Coil Heaters
3.1 Minimum Airflow
Ensure that sufficient airflow as marked on the name-
plate is passing through the heater. Airflow 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 airflow in the heater.
Use suitable airflow sensing device or interlock the
heater with fan. An insufficient airflow will lead to the
opening of the auto-reset thermal cut-out or damage to
the heating elements.
3.2 Warning
The air flowing through the duct where the heater is in-
stalled shall not contain any combustible particles, nor any
flammable vapor or gas.
3.3 Air Temperature
The air temperature should not exceed 120°F [49°C] at the
heater outlet.
3.4 Minimum Static Pressure and Air Direction
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” of water for a
constant flow.
3.5 Manual Reset Thermal Cut-out
This protection device is standard on all heaters of less
than 300 volt and 30 kW and is optional on all other heat-
ers. 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 neces-
sary to replace it before resetting the manual reset thermal
cut-out.
4 – Maintenance
All electric coil heaters have been designed to operate long
term without problems. Those responsible for equipment
and maintenance should be aware of the following sugges-
tions.
4.1 Visual Inspection
It is strongly recommended to complete a periodic inspec-
tion. This precautionary step will help to keep your instal-
lations 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.
4.2 Electrical Inspection
Two weeks after start-up, 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.
4.3 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.
4.4 Off-season Maintenance
Where tubular heating elements are used, it is strongly rec-
ommended 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 im-
portant not to power a heater when too low a resistance
to ground has been measured. It is also recommended to
pay attention to any other heater operating in normal condi-
tions. Control components such as step controllers or mod-
ulating valves (SCR) should be maintained and checked
according to respective Manufacturer’s instructions. Any
defective components should be replaced only with identi-
cal original parts.