Eclipse Combustion AIRHEAT AH-MA User Manual
Page 21
Eclipse AH-MA Air Heat Burner v2, Design Guide 160, 8/1/05
21
Step 3:
Ignition System
2. Burner Fuel Staging
To further increase the burner turndown, AH-MA v2.10 burners
can be fuel staged. This can be done by installing two or more
separate burners in a duct, each with its own gas control valve, or
by dividing a single burner assembly into separate zoned sections.
For example, to double the effective turndown, two burner
sections may be staged as shown in Figure 3.8 on the previous
page. If more heat is required, stage 2 is lit by simply supplying gas
to it. It will pilot from the adjacent stage.
Warning:
Lockouts must be provided to shut off gas flow to
stage 2 unless flame is proven on stage 1.
A spacer (part #76506) must be installed between the burner
bodies to separate the different gas feed sections.
Note:
Ignition performance is enhanced if the gas inlet to stage 2 is as
close to the piloting section as possible.
AH-MA v2.10 Air Heat burners have an integral spark-ignited gas
pilot for lighting the burner. The pilot fuel is fed into the pilot end
casting which is separate from the main fuel. A pilot adjusting valve
is required to adjust the pilot gas flow (Eclipse part number
12659 is recommended). The needed pilot capacity is 20,000 Btu/
hr, but the pilot will operate equally well at higher or lower inputs.
The pilot is shut off after successfully igniting the main burner to
protect the ignitor.
Local safety and insurance requirements demand that you limit the
maximum time that a burner takes to ignite. These time limits vary
from country to country. For the USA, the time limit is 15 seconds;
for Europe, it is typically 3 seconds. Local requirements may
require shorter time limits. Verify local regulation and insurance
requirements with the authority having jurisdiction.
The time that a burner takes to ignite depends on:
the distance between the gas shut-off valve and the burner
the air pressure drop across the burner
the gas flow at start conditions.