Aerovent IM-200 - Manual (Page 4)

Units ordered with the high-low fire option are supplied with
a 1" NPT SR600 two-stage valve mounted in the pipe train.
The SR600 provides an economical means of flame staging
where infinite modulation is not required. Turn-down on low-
fire is from 25% to 75% of high-fire. This valve is powered by
a 24 volt AC transformer. When the coil is energized, the valve
is at low-fire. When the coil is de-energized, it is at high-fire.
Adjustments
To check the minimum or low-fire and maximum or high-fire
pressures for the limits of modulation or staging, use the fol-
lowing procedures:
To set minimum or low-fire
1. Remove the cover plate 1.
2. Remove the high fire adjusting screw 2, spring 3, and
plunger 4. A small magnet is useful for this purpose.
Handle the plunger carefully to avoid marring or collecting
dirt. Do not lubricate.
3. Modulation or Staging: Using the low-fire adjusting screw
5 , set the manifold pressure to the manufacturer’s specifi-
cations (50% to 75% of high-fire).
4. Modulation or Staging: Cycle the solenoid gas valve to
check for proper ignition.
5. Modulation or Staging: Adjust the air shutter or increase
low-fire adjustment if needed.
6. Replace the plunger, spring and high-fire adjusting screw.
To set maximum or high-fire:
Note: To avoid danger of over-firing, make certain that the
inlet pressure is at 1.0" w.c. above the outlet pressure.
1. Modulation and Staging: Using the high-fire adjusting
screw 2, set the manifold pressure to the manufacturer’s
specifications. See page 1, Fig. 1.
2. Staging Only: Cycle the burner to check performance.
3. Replace the cover plate.
High-Low Fire Option
Make sure plunger
is installed as
above.
Aerovent | www.Aerovent.com
5959 trenton Lane n | minneapolis, mn 55442 | Phone: 763-551-7500 | Fax: 763-551-7501
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