Service manual

A DJM3.2 MANUAL
NOTE: The discharge temperature requirements can be modified with the use of
certain "reset" devices.
The gas valve's opening curves are programmed into the DJM3.2's logic. All air and gas control is done
electronically to simplify burner set up and eliminate the need to adjust troublesome mechanical air/fuel
linkages.
The DJM3.2 is a stand alone control device designed to provide most of the control requirements for a
heating only unit. The DJM3.2 will operate with either the standard circular Engineered Air DJ burner or
the newer Engineered Air rectangular shaped high turndown burner. The DJM3.2 is an improved version
of the original DJM and contains all the original DJM features plus additions or improvements in the
following areas:
Basic Features
1. The DJM3.2 is designed to be a stand alone DJ unit controller and will perform the following control
functions:
• Temperature Control
• Burner Management
• Supply Blower and Inlet Damper Control
• Optional Low Limit Control
2. Proportional and Integral (PI) control strategies result in greatly improved temperature control.
3. Wider discharge air temperature operating range. Both the set-point range and the reset range have
been expanded.
4. Built in discharge set point with a 50 to 95°F setting range on Fahrenheit models, 10 to 35°C on
Celsius models.
5. Supports one optional discharge temperature set-point reset from one of the following sources:
• Room
• Ambient
• 0-10 VDC
• 2-10 VDC
• 4-20 ma
6. Has a built in self-checking feature for the discharge air sensor.
7. Has a built in auto bypass low limit with optionally wired alarm output contact (LL). The low
limit uses
the main discharge air sensor for temperature checking.
NOTE: Low limit function can be disabled on Model 3.2 only.
8. Has input terminals for the fan switch, heat switch, and time clock contact.
9. Night heating and blower operation include the following:
A. Temperature control from:
• Room control with discharge sensor acting as a modulating high limit.
B. Supply blower operation:
• Intermittent fan (if night mode option selected).
• Continuous fan in day operation.
• Continuous fan operation at night if “K” and “FS” powered.
Page 2 Revised: 3/11/99