L.B. White Bloom 400, Инструкция и руководство пользователя

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Bloom 400 Greenhouse Heater
Owner’s Manual • Bloom 400
19
FIG. 7
B. Differential Air Pressure Switch
The air pressure switch is a safety device that works with
the ignition control in ensuring that the motor is up to full
speed before the gas control valve opens and the igniter
sparks.
See Fig. 8. The differences between pressure in the
fan section (po pressure) and the burner section
(negative – pressure) close the switch contacts. Power
that is sent to the switch when there is a call for heat is
returned to the ignition control, “proving” to the ignition
control that the switch is functioning. The control then
allows the ignition trial to proceed.
Ensure the switch’s tubes are firmly connected and not
blocked with dirt. This can also prevent proper function
of the switch.
To determine if the switch is defective, either:
• By-pass the switch
-- Do so ONLY after the motor first starts. By-passing the
switch prior to motor start-up will shut down the heater.
-- If the heater starts and burns, then the switch is
defective.
OR
• Obtain a volt meter and set it to AC volts.
-- Trace the electrical wire from terminal PSO to the
switch.
-- Start the heater
-- Verify 120 VAC to the switch.
-- Do the same test at the other terminal on
the switch.
-- If there is 120 VAC to the switch, but
voltage is not coming out being fed back
to PSI on the ignition control, replace the
switch.
When doing maintenance or service on the switch pressure
tubes, ensure the tubes are positioned as shown.
FIG. 8
FIG. 9
Relays
There are two relays in the control box. Although the same
part number, the relays are wired differently to control the
power supply to the motor for either Heat or Vent modes.
C. Heat Relay:
This relay receives incoming power from the greenhouse
temperature controller’s heating contacts and from the
heater’s ignition control to start the fan motor during the
heating phase.
See Fig. 10 and the terminal designators as shown below
when doing voltage checks on the heat relay.
Terminal Function
2 120 VAC from power supply to ignition control
(Heat)
4 120 VAC from relay to motor.
6 120 VAC to relay from power supply (Common)
8 120 VAC from relay to motor
0 120 VAC from ignition control (IND) to relay
(energizes relay)
1 120 VAC from power supply (Common)
POSITIVE (+)
NEGA
TIVE (-)
POSITIVE
PRESSURE
(+)
NEGATIVE
PRESSURE (-)
LED