Step 4: Ignition System - Eclipse RA Series Design Manual

Step 3: Control
Methodology
(Continued)
Step 4: Ignition System
12
Process
Set Point
Controller
Process
• The control motor modulates the air butterfly valve (BV) which
controls the combustion air flow.
• Air pressure in the burner body sends an impulse down the
loading line to the ratio regulator.
• The ratio regulator controls the gas flow in proportion to the air
flow.
Warning:
Do not use other control methods, such as, a fixed-air
control, and do not alter the ratio regulator or burner
piping without prior approval from Eclipse.
Ignition Transformer
For the ignition system, use a transformer with:
• secondary voltage 6,000 to 8,000 VAC
• minimum secondary current 0.02 amps continuous
• full wave output
DO NOT USE the following:
• twin outlet transformer
• distributor type transformer
Trial for Ignition
It is recommended that low fire start be used. However, under
certain circumstances RatioAirs are capable of direct spark ignition
at higher gas inputs.
Most local safety codes and insurance requirements limit the
maximum trial for ignition time (the time it takes for a burner to
ignite). These requirements vary from one location to another;
check your local codes and comply to the strictest codes
applicable.
The time it takes for a burner to ignite depends on the following:
• the distance between the gas shut-off valve and the burner
• the air:gas ratio
• the gas flow conditions at start-up
The possibility exists where the low fire is too low to ignite the
burner within the maximum trial for ignition time. The following
options must be considered under these conditions:
• start at higher gas input levels
• resize and/or relocate the gas controls
• use bypass start gas
Control
Control
Motor
Signal
Gas Flow
Eclipse RatioAir v1 Design Guide No. 115, 11/12/2008
Air
BV
Ratio
Regulator