Bryant Model 516 - Manual (Page 4)

Start-up, Adjustment.and Checkout
1. Turn on the electrical supply,
2 . Set the thermostat to call for heat.
3. The sequence of operation for 3 - through
9.6 -KW duct heaters is as follows:
A. When the thermostat calls for heating,
the primary contactor closes. See
Figures 1 and 2 .
B. The fan and heating elements are
energized at the same time.
4. Unit shutdown is as follows:
A. As the thermostat is satisfied, the
primary contactor coil is de-energized.
B. The fan and heating elements are de­
energized at the same time .
5. The sequence of operation for 11- through
14.4-KW duct heaters is as follows:
A. When the thermostat calls for heating,
the sequencer is energized. See Figure
3.
B. The fan is energized at the same time.
C . The heating elements are energized in
rapid succession.
6. Unit shutdown is as follows:
A. As the thermostat is satisfied, the
sequencer is de-energized.
B. The heating elements are de-energized
in rapid succession.
C . The blower motor is in operation until
the last heating element is de-ener­
gized .
Check the control circuit operation. Be sure
that the thermostat turns the unit on and off
when heating contacts are closed, then
opened. Be sure that the thermostat fan
switch (if there is one) turns the blower on
and off when switch is turned on, then off.
Replace all control box covers and outer
cabinet panels.
Minimum Air Velocities
The minimum airflow is directly related to
the inlet air temperature. Consideration must
be given to both the airflow across the heater
and the inlet temperature.
1. The amount of supplementary heat required
may be expressed in terms of KW as follows:
KW required
BTU Heat Loss
3413
2. If the air handling equipment is expressed
in CFM's, then a direct cross-reference can
be made by comparing the temperature of the
air (as it enters the duct heater) to the KW
rating on the chart at the rated CFM. See
Figure 4.
A. Draw a line horizontally from the inlet
air temperature to the KW (BTU) re­
quired,
B. From this point of intersection on the
KW line, draw a line down vertically to
establish the CFM. See Table II for the
CFM at a given static pressure.
C. The CFM should never be lower than
the CFM as determined from the chart.
In cases where this is not true, then
the CFM must be increased or the KW
required must be reduced.
3 . In cases where the air handling equipment
is expressed in FPM, convert to CFM by
multiplying the FPM by the duct area.
Example:
Air Velocity = 1000 FPM
Duct Size = 8
X
20 in. = 160 sq in.
Duct Area =
-
1.11 sq ft
144
Airflow = 1000 FPM
X
1 .11 sq ft = 1110 CFM
SECTION II
If the electric duct heater package is used
with an air handler other than our Model 516
Fan Coil Unit:
1. All previous instructions, limitations, and
recommendations apply to this type of instal­
lation .
2 . The duct heater must be mounted 48 inches
downstream from the air handler. It cannot
be mounted 6 inches downstream as on the
Model 516 Fan Coil Unit.
39516D3
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