Model 4
1500 - 6000 MBTU/hr
Rev. 03-08
Section B2-6
Gas Train consists of the following:
•
Primary gas shutoff valve with integral proof of closure switch.
• A
manual shutoff valve located ahead of the primary gas valve.
• A
plugged leakage test connection and a second manual shutoff valve for tightness
checking of the primary shutoff valve.
• Separate Gas Pressure Regulators for the pilot train and main gas train.
• Low
Gas Pressure and High Gas Pressure Switches for units at 3000 and greater.
• A
second motorized gas valve is provided in addition to the primary valve on size
6000 units.
• The pilot gas train includes a manual shutoff valve and solenoid shutoff valve.
3. Boiler Trim and Controls
A. 15 psig or 150 psig set A.S.M.E. safety relief valves.
B. Steam pressure gauge with inspectors test cock and connection.
C. Primary Water Column complete with gauge glass and column drain valve.
D. Low Water cutoff switch and pump control switch, integrally mounted in the
primary water column.
E. Auxiliary Low Water Cutoff, manual reset type.
F. Steam Pressure Controls:
• Operating Limit.
• Excess Steam Pressure (High Limit), manual reset.
• Burner firing rate, low high low.
4. Burner Control Panel and Controls
A. The control panel is enclosed within a NEMA 1A Rated enclosure, mounted on
the burner wind box at approximately eye level height.
B. Mounted within or on the control panel box are the following controls. Panel
wiring is factory tested.
• Combustion Flame Safeguard Control, Model CB120 that provides pre purge, post
purge, trial for ignition, main flame/burner operation, and safety shutdown.
• Fan Motor Starter wired into the non recycling circuit of the flame safeguard
control.
•
Indicating Lights for low water, flame failure, load demand, and fuel valve on.
•
Burner On/Off Switch.
• Damper Positioning Switch.
•
Fuel Selector Switch for combination fuel fired burners.
•
Control Circuit Step-down Transformer with primary fuse protection.
•
Terminals for interface wiring connection of controls.
• Oil,
heat,
and
moisture resistant wire used. Each wire is number coded relative to
the wiring diagram.
5. Electric Service Panel
An electric service panel (entrance box) is provided on the side of the boiler for all
external wiring connections to remote control devices and the main power for the
boiler. Wiring to this panel eliminates the need to disconnect wiring when the front
burner wind box is opened for burner or boiler servicing.
