SA-Series Technical Manual
15
Cambridge Air Solutions
MOTOR AMP DRAW CHECK
IMPORTANT
The blower access door must be closed for this test.
1. Turn the blower service switch to the “LOCAL”
position and let the motor warm up.
2. Check motor current at the motor starter.
3. Turn the blower service switch to “OFF” position.
IMPORTANT
The motor current must not exceed 103% of the Motor
Nameplate FLA. High amperage may indicate excessive
blower RPM
BURNER MANIFOLD PRESSURE ADJUSTMENT
1. Turn off the disconnect switch (by others).
2. Remove the wire from terminal #3 on the amplifier.
This will drive the modulating valve to full open.
3. 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.
4. Refer to the heater nameplate for the Manifold
Differential Pressure (MDP) and record in step 7.
5. Turn on the disconnect switch (by others).
6. Turn the blower service switch to the “LOCAL”
position. The blower motor will start. Observe the
pressure reading on the manometer and record in
step 7. (Note whether the reading is positive or
negative.)
7. Using the formula below, determine the required
manifold pressure reading for the manometer.
Nameplate MDP
_______ " WC
Manifold Static Pressure
(Blower Only) + _______ " WC
Manifold Pressure Reading = _______ " WC
IMPORTANT
A negative manifold static (blower only) will cause
the manifold pressure reading to be lower than the
nameplate manifold differential pressure.
8. Turn the burner service switch to the “LOCAL”
position. After a delay for prepurge and igniter
warm-up, the burner will light. Allow 15 seconds for
the low fire start to time out.
9. Observe the manometer reading and compare to
the manifold pressure determined (Step 7). If the
manifold pressure reading does not equal this value,
adjust the control regulator until the proper manifold
pressure is obtained.
10. Turn the blower and burner service switches to the
“OFF” position.
11. Reconnect the wire to terminal #3 on the amplifier.
MINIMUM FIRE ADJUSTMENT
The minimum fire setting is preset at the factory at
approximately 20°F rise.
IMPORTANT
A DC microammeter is required to monitor flame
signal during the adjustment procedure. Ensure the
flame signal remains steady and of sufficient strength to
maintain burner operation for both consistent ignition
at minimum fire and locking in the flame safeguard
relay. Do not allow the flame signal to drop below 2.0
microamps DC.
1. Remove the cover of the Discharge Air Temperature
Sampling Box. Refer to the Heater Configuration
(page 5) for the Discharge Air Temperature Box
location, and the Individual Component Description
Section (page 39) for additional information. Install
a thermocouple in the grommet inside the Discharge
Air Temperature Sampling Box, and then reinstall
the cover. Route the thermocouple wire to a meter
located outside of the unit.
2. Turn the blower service switch to the “LOCAL”
position and monitor the discharge temperature.
3. Remove the wire from terminal #8 on the amplifier.
This will cause the burner to light on low fire and
then fall to minimum fire.
4. Turn the burner service switch to the “LOCAL”
position. After a delay for prepurge and igniter
