Service manual

A DJM3.2 MANUAL
NOTE: If room reset calling, the “calculated” discharge temperature set-point will vary
from the setting of “master” set-point.
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The room-reset feature is activated by dipswitch 3.
Room sensor calibration pot is Pot Room Cal.
Reset ratio pot is
Pot Reset Ratio (refer to table below for values).
Room reset band is ±3ºF (fixed).
The “room reset band” means a room temperature error of just 3ºF will result in a maximum reset of
the discharge air set point. The actual amount reset (in degrees) varies as per both the setting of Pot
Reset Ratio and the discharge set point. The calculated discharge air set point (dial setting + reset) is
limited between 48 and 120ºF.
To determine the amount of reset available use the following table.
EXAMPLE: DJM3.2 set-point 70ºF; pot #5 set at 3; room thermostat set 75ºF.
• If room thermostat sensor is at 75ºF - no reset, discharge at 70ºF.
• If room sensor is 3° cold (72ºF), discharge is reset up full amount of its authority (+20) to 90ºF. If
room thermostat was at 73ºF then β of the reset would be used (
β * 20 adds about 14º), added on
to the set-point of 70ºF giving discharge of 84ºF.
• If room sensor is 3º hot (78ºF) full reset down will lower the discharge 13º (70 - 13 or a 57ºF
discharge).
ROOM RESET AUTHORITY TABLE
(also used to determine settings when Make/Break Thermostat is calling or not calling)
Page 13 Revised: 3/11/99