63
Components
The following image and list outline the typical direct fired heater components and their functions.
Figure 31 - Typical Cabinet Components
1.
VFD
– Optional component. Adjusts speed of 3-phase motors by changing the frequency signal sent to
the motor.
2.
Power Transformer
– Optional component. Installed when motor voltage is greater than120V. Used
to provide 120V service to controls.
3.
Terminal Strip
– Central location to terminate control wiring. Should be used for troubleshooting.
4.
Flame Safety Control
– Initiates and monitors flame.
5.
Ignition Transformer
– Produces high voltage spark to ignite flame.
6.
HMI
– MUA board interface. The 4 buttons are used to navigate through the menu screens.
7.
Make-up Air (MUA) Board
– Monitors and outputs electrical
signals for components and functions on
the unit. Also, the MUA board contains an airflow sensor.
8.
Transformer
– 20VA 120V to 24V.
9.
Clogged Filter Switch
– Optional component. Senses whether the filters at the intake to the main
supply motor are free of dirt and contaminant.
10.
Gas Inlet
– Main gas supply connection.
11.
Inlet Gas Pressure Gauge
– Inlet gas pressure should be read from here.
12.
Combination Gas Valve
– A combination of redundant solenoid valves, pilot valve, and gas regulator
built into one unit.
13.
Modulating Gas Valve
– Modulates gas flow to the burner to provide proper air temperature.
14.
Manifold Gas Pressure Gauge
– Manifold gas pressure should be read from here.
15.
Manual Gas Shut-Off Valve
– Allows gas flow to the burner to be shut off to leak-test gas train.
1
2
3
4
5
SPACE
70°F
OCCUPIED
IDLE
6
7
9
8
10
11
12
13
14
15
Summary of Contents for MUA Controls
Page 82: ...82 Notes ...
Page 83: ...83 CLEANING MAINTENANCE RECORD Date Service Performed ...
