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Key to System Schematics
Symbol
Appearance
Name
Remarks
Bulletin/
Info Guide
ExtensoHeat Burner
235
Main Gas Shut-Off Valve Train
Eclipse strongly endorses NFPA
as a minimum
756
Combustion Air Blower
The combustion air blower
provides the combustion air
pressure to the burner(s)
610
Air Pressure Switch
The air pressure switch gives a
signal to the safety system when
there is not enough air pressure
from the blower
610
Gas Cock
Gas cocks are used to manually
shut off the gas supply on both
sides of the main gas shut-off
valve train
710
Solenoid Valve (Normally Closed)
Solenoid valves are used to
automatically shut off the gas
supply on a bypass gas system or
on small capacity burner systems
760
Manual Butterfly Valve
Manual butterfly valve are used to
balance the air or gas flow at each
burner, and/or to control the zone
flow
720
Automatic Butterfly Valve
Automatic butterfly valves are
typically used to set the output of
the system
Motorized Gas Control Valve
A motorized gas control valve
adjusts the gas flow to the
burner(s) based on the control
system requirements
Adjustable Limiting Orifice
Adjustable limiting orifices are
used for fine adjustment of gas
flow
728/730
Pressure Taps
The schematics show the advised
positions of the pressure taps
Main Gas
Shut-Off
Valve Train
P
NC
M
