S-Series Technical Manual
55
Cambridge Air Solutions
positive shut-off high pressure regulator must be
added upstream of the heater’s individual low
pressure manual shut-off valve. If a high pressure
regulator is needed and has not been installed, check
with your local agent or Cambridge Air Solutions'
Customer Service Group at 1-800-473-4569 to
determine the size and capacity requirements.
m
WARNING:
When disconnect switch is activated with
enclosure open, live power is present. Only
experienced technicians with knowledge and
respect for live power should proceed beyond this
point.
4. BLOWER ROTATION CHECK
a. Open the access door on the electrical control
enclosure side and turn the disconnect switch to the
”ON” position.
b. Turn the blower service switch to the ”LOCAL”
position. Blower motor will start after the
motorized damper opens. Then, turn the blower
service switch to the ”OFF” position and verify
the blower is rotating clockwise from the control
enclosure side.
IMPORTANT
On a three phase system, the rotation direction of the
blower may be reversed by switching any two wires
located on the downstream side of the motor starter.
The electrical supply to the heater must be turned off
prior to switching the wiring.
IMPORTANT
Indications of loose belts include barking or
squealing when the blower starts. If these
symptoms occur, please refer to the Belt Tensioning
instructions (page 45)
IMPORTANT
The damper will remain in the open position as
long as the blower service switch is not returned to
the ”REMOTE” position or the Low Temperature
Cutout (LTC) function has not timed out.
5. MOTOR AMP DRAW CHECK
IMPORTANT
The heater access doors must be closed for this test.
a. Turn the blower service switch to the ”LOCAL”
position and let the motor warm up.
b. Check motor current at the overload on all three
legs.
c. Turn the blower service switch to the ”OFF”
position.
IMPORTANT
The average amps must not exceed 103% of the
Motor Nameplate FLA. High amperage may indicate
excessive blower RPM.
6. BURNER MANIFOLD PRESSURE
ADJUSTMENT
a. Turn the disconnect switch to the “OFF” position.
b. Drive the modulating valve to fully open.
b.1 For EDL, EDR, EDSM, and EDSM/TP control
systems, remove the wire from terminal #3 on the
amplifier (see Figure 1).
Figure 1
b.2.a. For EDSC control systems, remove the wires from
terminals #T1 and #T2 of the amplifier and connect
an 1100 Ω resistor across terminals #T1 and #T2 of
the amplifier
OR
Remove the discharge temperature sensor from the
discharge duct.
b.2.b. Provide a control signal (4-20 mA / 0-10 VDC) to the
amplifier by setting the signal level thru the Building
Automation System
OR
Remove the wires from terminals #5 and #6 of
the amplifier and connect a current/voltage signal
generator to terminals #5 and #6 of the amplifier.
(Note polarity of the terminals: #5 is negative and #6
is positive)
b.2.c. Set the modulation level to 100% (20 mA / 10 VDC).
c. Remove the 1/8" plug from the manual shut-off valve
located just prior to the burner, and connect a manometer
for the purpose of measuring the manifold pressure.
d. Refer to the heater nameplate for the Manifold
Differential Pressure (MDP) and record below.
