Service manual

A DJM3.2 MANUAL
1195 RPM, 19.91 Hz.) Voltage to the series 50 valve should be 0 volts DC. Adjust the spring
activated low fire adjustment at the top of the modulating gas valve (small screw) until an O
2
reading of 16.8% to 17.5% is achieved.
9. Lock the low fire adjustment screw as described in point 7 above and then adjust the curve
matching pot as in points 5 and 6 above.
Type ES345D-L (high turndown)
As this valve has 2 low fire adjustments the following procedure should be applied.
10. Bring the unit to low fire using the service firing pot fully CCW. Adjust Pot Low Fire until the
combustion fan is turning 1250 RPM ±10 RPM (20.8 Hz). (15:1 turndown is 1195 RPM, 19.91
Hz.) Voltage to the ES valve should be 0 volts DC. The low fire bypass adjustment on this
valve is under the top cover on the large port and the adjustment inside it is marked:
Increase ÍÎDecrease
After removing the cover, loosen the locking screw first before making adjustment. This
should be done at 0 VDC to the modulating gas valve terminals and the spring activated
low fire brass screw turned fully CCW and the locking ring loosened off.
11. Bring voltage to gas valve at 2.25 VDC and adjust the spring activated low fire adjustment
located in the head with the electric modulator (smaller screw under cap) to achieve the same
O
2
reading as the one achieved at 0 VDC (16.8% to 17.5% O
2
). After this is complete then
adjust the curve matching pot 1 as described in points 5 and 6 above.
Pilot Set Up (high turndown)
1. On high turndown units, ensure air tube to pilot is free of debris and blockages and then set pilot
pressure to 3.5" WC.
2. Pilot set up is not as critical on the high turndown burner as there is not as much heat on it as on
the regular burner.
Standard (Round) Burner
Most standard turndown DJ units will employ one of the following Maxitrol modulating DC volt gas
valves.
Series 20
Β M520, M620 These valves do not have high fire regulators. High fire
pressure is set up at the appliance regulator. If used on the
standard burner, the low fire adjustment located on the bottom
side of the valve is to be adjusted fully clockwise (no bypass).
Series 50
Β M550, M650, ES350. These valves do not have high fire regulators. High fire
pressure is set up at the appliance regulator. This series of
valve has been replaced with the M520/620 series.
ES345D-L This valve has a built in high fire regulator.
High Fire Set Up
1. Turn on the service switch (dipswitch 5).
2. Set manual firing Pot Hi Service (located next to the + terminal) to high fire. Adjust the high fire
input to the correct clocked rate. Adjust the combustion air slider or inlet damper until the high
fire O
2
reading is between 3.5 and 4.2%.
Low Fire Set Up
Standard Burner Low Fire Set Up 2.5:1 turndown
Low fire blower input is 40% of high fire blower input.
Page 32 Revised: 3/11/99