Control System Requirements; Check Valve Operation; Pressure Switch Location - Eclipse Combustion AH Installation Manual

2.0

Control System Requirements

Turndown Method
Regulator Loading Lines
Piloting
Ignition
Check Valve
w
Warning
Pressure Switch Connection
Limit Controls &Safety Equipment Limit controls and safety equipment should comply with current NFPA Stan-
Figure 3–Check Valve Operation
WARNING!
Do Not Install Any Valves Here!
See Section 2.0
Process Air
Check Valve Opens When
Gas Inlet Pressure Is at Low Fire
4
Input is normally controlled by a motorized butterfly valve in the gas line to the
burner.
Connect the top diaphragm chambers of the main gas and pilot gas regulators to the
duct approximately 10" downstream of the burner. This will allow the regulators to
maintain a constant supply pressure to the burner regardless of varying pressures in
the duct.
Pilot gas flow is adjusted as shown in Figure 6.
Ignition voltage should be 6000 VAC.
See Figure 3. At high fire, the gas pressure at the burner inlet is higher than the air pressure, and
the check valve is closed. At low fire, gas pressure falls below the air pressure, and the check
valve opens, permitting a small amount of air to mix with the gas. This premix at low fire stabilizes
the flame and helps distribute the flame evenly down the length of the burner.
Do not install any valve or controlling device in the gas line between the
burner and the check valve tee, Figure 3. Because this section of the gas
line carries a partial pemix at low fire, it is possible under unusual condi-
tions for the flame to travel back through the pipe to the tee. Devices in-
stalled in this section may be damaged and may melt, releasing gas to the
atmosphere and causing fires or explosions.
See Figure 4 for typical connection of combustion air and circulating fan limit
switches.
dards* 86 and 86C, and all applicable local codes and/or standards.
*Available from:
National Fire Protection Association
Batterymarch Park
Quincy, MA 02269
Tee
Gas Inlet
Manifold
Eclipse AirHeat v1.0 - Installation Guide No. 140, 11/4/03
American National Standard Inst.
1430 Broadway
New York, New York 10018
Figure 4—Pressure Switch Location
Tube at
Blower Inlet
Tube Points
Upstream
Circulating Air
Pressure Switch
Blower
Pressure Switch
P
Burner Air Tap
Lo Hi
See Figure 7
P
Tube Points
Hi Lo
Downstream