EngA ENGINEERED AIR DJM2.4, Installation, Operation And Maintenance Manual, Page: 23 / 37

DJM2.4 MANUAL
23 Oct 00 R2
This reading is used to determine the adjustment that will usually give the best pilot lighting
and proving strength. However, care must be taken to not adjust the reading for pilot gas
pressure below 2.5 inches water column pressure or you will break the pilot ceramics.
Next, visually observe the pilot flame. It should be visible at a minimum of 3 of the holes
around the pilot. If the pilot cannot be seen then it is likely burning too deep into the pilot
box. If this is occurring check that the gasket on the pilot assembly is forming a tight seal. Also
ensure that the burner is located in the centre of the burner tube. If it is mounted too low
then too much air can flow over the top of the burner and affect the pilot.
Propane Gas
Due to
the quantity of fuel that can be drawn off a propane tank, it is often necessary to equip a propane
fuel system with a vaporizer. The usual sign that a vaporizer is required is that the units fuel
supply falls off as the line “freezes”. The user usually observes:

Lack of temperature rise,

Rumbling or shaking burner due to air/fuel mix,

After turning the unit off for awhile the fuel line thaws and upon restarting it, all appears to
be normal.
Combustion set up for propane fuels for either the high turndown or the standard burner are
similar to the above. The only modification suggested is it may be desirable to increase the
oxygen settings by 1 to 1.5% above those for natural gas.
High turndown burners operating on propane fuel will generally exhibit the following:
High Fire 3.5% O
2
will appear yellow from behind the burner. However, if you could view it
from the other side of the burner you would see blue as the flame lengthens out.
Low Fire 16% O
2
The flame will likely be yellow. At 17% O
2
the flame will likely be blue and
yellow.
Inlet/Manifold Pressure Settings
Manifold pressure settings that the unit was tested and clocked at in the factory are recorded on
the unit rating plate. Any attempt to clock a unit in the field should be done with care as
corrections for density
(altitude and station pressure) , temperature, and the correction factor for
the meter are often overlooked, leading to an incorrect conclusion.
Inlet gas pressures are recorded on the unit label. At high fire inlet gas pressure to the unit should
not fall below 6.25" on units designed for 7" inlet pressure. If design is for 14" pressures should
not fall below 12".
If design is for 11" propane gas, then inlet pressures should not fall below 10". Note that with
propane fired units it may be necessary to equip the propane system with a properly sized
vaporizer.
OK Too large a gap.
Raise burner plate
up to centre.