Greenheck Duct Heaters Series IDHB and IDHC (478052) - Manual (Page 7)

Troubleshooting Guide cont....
7. Never install a standard heater into a duct
with an internal obstruction. An obstruction
can block airflow at the temperature limit
controls and element terminations. If this
situation exists, it can be corrected by
using a heater with recessed control box
and reduced wrapper size. This situation is
common with internally insulated ducts (see
Figure 8).
8. Never insulate the exterior of the control
box. The control must be completely
accessible and located where ventilation
can be provided at all times (see Figure 9).
9. Never install a heater near a double blower
outlet. A heater must be installed far
enough away from a double blower outlet
so that even and proper airflow is present
or separate duct heaters placed in the duct
runouts of each blower (see figure 10).
10. Order the heater with the factory installed
linear temperature limit control if the heater
width is greater than 72 inches.
11. Never use aluminum conductors. Use
copper conductors only for all incoming
wiring.
12. Never install a standard heater outdoors
without making special provisions to
protect the heater and control box from
the elements.
13. Never bundle, tie or wrap power wiring.
The wire could overheat or the insulation
could breakdown.
14. Never use a different voltage and/or phase
than what is listed on the heater nameplate
label. The duct heater is to be used only at
the voltage and phase that is listed on the
nameplate label.
Note: An airflow switch only proves that airflow
exists (a differential in static pressure), not that the
minimum air velocities and proper air distribution for
the duct heater exist.
FIG. 5
Air Handler
FIG. 6
Humidifier
FIG. 7
Air Filter
AIR HANDLER
HEATER
HEATER
HUMIDIFIER
AIR FILTER
HEATER
48" MIN.
48" MIN.
DUCT
DUCT
DUCT
48" MIN.
DUCT W/ INTERNAL INSULATION
DUCT W/ EXTERNAL INSULATION
CORRECT INCORRECT
CORRECT INCORRECT
FIG. 8
FIG. 9
FIG. 10
INCORRECT
DUCT W/ INTERNAL INSULATION
DUCT W/ EXTERNAL INSULATION
CORRECT INCORRECT
CORRECT INCORRECT
FIG. 8
FIG. 9
FIG. 10
INCORRECT
7