Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) - Manual (Page 37)

MAMM-VHC-IOM-1A (JANUARY 2013) 37
This electric heating coil module covered by this appendix
is a component of a “Listed” product, subject to the guide-
lines of application as designated by the Certifying Agency
and outlined in the appliance Manufacturer’s installation
and operation instructions.
The information provided in this appendix applies to the
electric heating coil module, installed in the appliance and
to its operation, maintenance and service. Refer to the ap-
pliance manufacturer’s instructions for information related
to all other components.
1 – Mechanical Installation of Electric Coil
Heaters
1.1 Handling
1.1.1 Remove the shipping covers just before installa-
tion.
1.1.2 Inspect the heater carefully and report any dam-
age to the manufacturer.
Do not install a damaged heater.
1.2 Installation
Heater Position
1.2.1 The axis of the duct must always be perpendicular
to the face of the heater.
1.2.2 The heating elements must always be installed
horizontally.
Model SC or ST (Slip-in Type)
1.2.3 Cut an opening in the side of the duct.
1.2.4 Slip the heater into the duct until the hole is com-
pletely covered by flanges around the heater.
1.2.5 Fasten the heater to the duct with sheet metal
screws and seal openings with a suitable sealing
compound.
1.2.6 If the heater is heavy, use additional hangers to
support the heater.
Model FC or FT (Flanged Type)
1.2.7 Flange both ends of the duct outwards on three
sides to match the heater’s flanges.
1.2.8 Fasten the heater to the duct with sheet metal
screws (for heavy heaters, use nuts and bolts and
additional hangers to support the heater).
1.2.9 Seal openings with a suitable sealing compound.
2 – Electrical Installation of Electric Coil
Heaters
2.1 Disconnect Power Source
Disconnect all power sources before opening the control
box and working within.
2.2 Read Nameplate
Read the nameplate carefully and consult wiring diagram
before starting to wire.
2.3 Supply Wires
Use only wires suitable for 167°F [75°C]. Wires shall be
sized according to the Canadian Electrical Code require-
ments. All wires must be brought in through knock-outs.
2.4 Disconnecting Means
Install a disconnect switch close to the heater according to
the code unless a disconnect switch is already built into the
heater.
2.5 Control Circuit Wiring
Use Class 2 wiring for control circuit connections to the
duct heater.
2.6 Magnetic Contactors
If magnetic contactors are mounted outside of the duct
heater, use only contactors approved for:
• 250,000 operations when controlled by auto-reset
thermal cut-out (A) and by other switching devices in
series with this cut-out (thermostat, step controller,
airflow switch, etc.).
• 100,000 operations when controlled by auto-reset
thermal cut-out (A) alone.
• 100,000 operations when controlled by auto-reset
thermal cut-out (A) plus manual reset cut-out in series
(A & M).
• 6,000 operations when controlled by manual reset
cutout (M) alone.
2.7 External Controls Ratings
Rating of external control devices shall be suitable for han-
dling the VA ratings as marked on the nameplate; other-
wise, a backup relay must be used.
2.8 Airflow Interlock
Heaters are generally supplied with one extra terminal
marked for fan interlock or air sensing device connection.
Remove jumper between terminals I and C before con-
necting the fan interlock. Select a suitable airflow sensing
device of the differential pressure sensing type, with snap
acting contacts. A slow make, slow brake device may
cause undue cycling and in some instances chattering of
the contactors. When fresh air dampers are used, make
Appendix J: Electric Heating Coil and Controls Information
IMPORTANT
• Do not install spray humidifiers upstream of duct.
Install it downstream instead.
• Do not cover the control box with thermal insulating
materials.
• Use special air intake louvers of weatherproof con-
struction for preheat duct heaters to avoid intake of
water or snow particles.
• Make sure that motorized damper blades are not
blocked with snow or dirt. Inspect the dampers regu-
larly to ensure a suitable airflow.