Service manual

A DJM3.2 MANUAL
NOTE: After set up is complete make sure to turn off dipswitch 5.
Propane Gas
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.
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 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 At 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 At 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, thus 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.
XXIII. SPECIAL SERVICE NOTES
On Board Fuse
The DJM3 is equipped with a 2-amp fuse. This fuse is located on the bottom of the main board. If
there is 24 VAC to terminals T1 and T2 and the DC voltage from terminals O to G is 0 VDC, check the
fuse. (10.5 to 11.0 VDC is normal.)
Resetting Low Limit, Bad Sensor, Flame Failure Lockout
This can be done by either removing power to the DJM3 or by just removing the power to terminals
“HS, FS”, and “K”. (Refer to Page 8 “Resetting Low Limit”.)
Page 34 Revised: 3/11/99