U.S. Boiler Company INDEPENDENCE, Installation, Operating And Service Instructions

41

3.  Adjust limit to setting above observed reading. Main 

burners should reignite.

4.  Adjust thermostat to lowest setting. Adjust limit to 

desired setting.

K.

  Adjust gas input rate to boiler. 

Natural Gas.

1.  Adjust thermostat to highest setting.
2.  Check manifold gas pressure. Manifold pressure is 

listed on Rating Label.
a.  Models IN10-IN12 with Standing Pilot and 

IN3I-IN11 with Electronic Ignition.  Adjust gas 

valve pressure regulator as necessary (turn 

adjustment screw counterclockwise to decrease 

manifold pressure, or clockwise to increase 

manifold pressure). If pressure can not be 

attained, check gas valve inlet pressure. If less 

than minimum gas supply pressure listed on 

Rating Label, contact gas supplier for assistance.

b.  Model IN12 with Electronic Only.

i.

  Turn off gas valve not having pilot control.

ii.

  On gas valve with pilot control, adjust gas 

valve pressure regulator to obtain required 

manifold pressure, or if unattainable, highest 

pressure without forcing adjustment screw 

(turn adjustment screw counterclockwise to 

decrease manifold pressure, or clockwise to 

increase manifold pressure).

iii.

  Turn on gas valve not having pilot control. 

Adjust gas valve pressure regulator to obtain 

required manifold pressure. Manifold 

pressure may not change during initial turns 

of adjustment screw.

3.  Clock gas meter for at least 30 seconds. Use Table 

10 to determine gas flow rate in Cubic Feet per 

Hour.

4.  Determine Input Rate. Multiply gas flow rate by gas 

heating value.

5.  Compare measured input rate to input rate stated on 

Rating Label. 

a.  Boiler must not be overfired. Reduce input rate 

by decreasing manifold pressure. Do not reduce 

more than 0.3 inch w.c. If boiler is still overfired, 

contact your local distributor for replacement 

Gas Orifice.

b.  Increase input rate if less than 98% of Rating 

Label input. Increase manifold gas pressure no 

more than 0.3 inch w.c. If measured input rate is 

still less than 98% of rated input:

i.

  Remove Main Burners per procedure in 

Section X: Service Instructions.

ii.

  Remove gas orifices. Drill one (1) drill size 

larger (drill size is stamped on orifice).

iii.

  Reinstall gas orifices and main burners. 

Measure input rate.

6.  Recheck Main Burner Flame.

7.  Return other gas-fired appliances to previous 

conditions of use.

L.

  Adjust gas input rate to boiler. 

LP/Propane.

1.  Set thermostat to highest setting.
2.  Adjust tank regulator for gas valve inlet pressure of 

13.5 inches w.c. or less. 

3.  Gas valve has step opening regulator which initially 

opens to 1.4 or 2.5 inch w.c. and steps to full 

pressure after approximately 30 seconds. Check 

manifold pressure after step has occurred. Adjust gas 

valve pressure regulator as necessary for 10.0 inches 

w.c. (turn adjustment screw counterclockwise to 

decrease manifold pressure, or clockwise to increase 

manifold pressure). If 10.0 inches w.c. can not be 

attained, check gas valve inlet pressure. If less than 

11.0 inches w.c., contact gas supplier for assistance.

M.

 Clean Heating System (Steam).

  A local qualified 

water treatment chemical specialist is a suggested 

source for recommendations regarding appropriate 

chemical compounds and concentrations which are 

compatible with local environmental regulations.
1.  Oil from new piping connections and sediment in 

existing piping must be removed from system to 

prevent unsteady water line and carry-over of 

entrained water into supply main.
a.  Fill boiler to normal waterline.
b.  Follow Lighting or Operating Instructions to 

place boiler in operation. See Figure 38, 39 or 

40.

c.  Operate boiler with steam in entire system for 

several days to bring system oil and dirt back to 

boiler.

d.  Drain condensate from drain valve in wet return. 

Operate boiler until condensate runs clean.

2.  Boil-out boiler.

a.  Follow instructions TO TURN OFF GAS TO 

APPLIANCE. See Figure 38, 39 or 40.

b.  Fill boiler to normal waterline.
c.  Remove safety valve.
d.  Pour recommended boil-out compound into 

boiler through safety valve opening.

e.  Reinstall safety valve in Tapping "E" with 

spindle in vertical position.  See Figures 1 and 2.

f.  Follow Lighting or Operating Instructions to 

place boiler in operation. See Figure 38, 39 or 

40.

  Check controls operation per Paragraphs F to J. 

Boil water for at least 5 hours.

g.  Follow instructions TO TURN OFF GAS TO 

IX.  System Start-up (continued)