Specifications

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If flame signal drops significantly when main gas valves
open, slightly increase pilot gas pressure to attain a
steady flame signal.
After the burner lights; adjust gas pressure regulator,
using a manometer, and combustion air damper to
match firing rate shown on unit nameplate. Make sure
the thermostat and gas valves are in high fire.
These units have an induced draft fan, a minimum of
-0.20” W.C. must be maintained at the relief door,
simultaneously while setting the fuel to air pressure on
the burner at full input. This is done by changing the
damper setting at the induced draft fan outlet. Be sure to
lock down the locking quadrant when you are done.
Check all gas piping again for leaks using a soap bubble
solution.
On-Off Operation
Check to make sure operating thermostat cycles burner
and induced draft fan.
See final checks and adjustments.
High-Low-Off Operation
Turn the two stage thermostat down slowly until main
gas valve begins to drive closed (low fire) or the power
on the second stage may be disconnected.
NOTE: Low fire rate should be set at approximately
50% of high fire.
CAUTION: Too low of an input setting will cause
condensation of the flue gases.
To reset low fire, remove the cover from the Two Stage
gas valve actuator and using the wrench provided read-
just the internal cam setting.
Check to make sure Two Stage thermostat cycles
burner and induced draft fan.
See final checks and adjustments.
Modulating Operation
Set high fire by adjusting main gas regulator and by the
high fire adjusting screw on the butterfly valve.
Turn all modulating thermostats to their lowest setting
without turning the burner off, or with power off remove
the coil wire on low fire hold relay and restart burner.
Observe flame as burner modulates.
NOTE: Flame should modulate slowly and evenly
throughout the entire travel, although flame may
become somewhat "dirty" during travel. If stopped
at any point, proper combustion should resume.
Observe low fire, it should be substantial enough to
maintain proper combustion and be within the designed
turndown range of the burner.
Set low fire with the low fire adjusting screw on the
butterfly valve.
CAUTION: Too low of an input setting will cause
condensation of the flue gases, this should be
avoided unless condensate drains are provided.
See following drawings for operation of modulating ther-
mostat and typical circuit. SW-13 should cycle the
burner.
See final checks and adjustments.