DJM2.4 MANUAL
35 Oct 00 R2
Low fire combustion blower speed
10:1 turndown is about 1250 RPM ±10 RPM (20.8 Hz)
15:1 turndown is about 1195 RPM ±5 RPM (19.91Hz) [1150 to 1400 RPM]
High fire combustion blower speed is about 3400 RPM
Light off speed is about 2300 RPM
Maxitrol Modulating Gas Valve Voltages
The different Maxitrol valves reach high fire at about the following voltages:
M650 or M651 2 - 13 VDC
M550 or M520 2 - 12 VDC
M450 or M420 2 - 11 VDC
MR212 2 - 11 VDC
Low fire is at about 2 VDC on each of the above valves.
DJM2 Slaving From C-TRAC
Occasionally reports are received where a C-TRAC, acting as the main temperature control (with
the DJM2 its slave) cycles from heat mode to free cool mode (neither heat nor cool light on) then
back to heat mode. This results in excessive temperature swings due to the time delays as the C-
TRAC changes modes. To reduce this occurrence:
Firstly, ensure the CONT, BMSS and BMSZ pots are correct as described in the DJM2 manual
section X.
Secondly, if the above does not resolve the problem, adjust the C-TRAC COOLING DEADBAND Pot
#3 to number value eleven. Also access the C-TRAC Pot eleven on the back of the C-TRAC and set
it to number 2.
Thirdly, if the above steps do not resolve the issue, use an open sensor (contact the factory for
details).
Fourth, if after doing the above and reasonable control cannot be attained, contact the factory
about “Splitting” the C-TRAC and DJM2 apart.
DJM2.x Applied to a “SH” (Steam Humidifier)
The DJM2.x has been applied to the SH product line to control the burner that is providing heat
for the formation of steam. Operation is very similar to that of heating air except that water is
being maintained to a temperature adequate to provide enough steam to meet the demands of
the steam distribution system.
Items to be aware of on SH units are:
- SH units are shipped from the factory with a condensate line that is open to
atmosphere. If it is to be used it must either be gravity fed from the bottom of the
steam grid or if the steam grid is below the level of the condensate return then a
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