Carlin 702GAS Inst Manual - Manual (Page 18)

Model 702GAS Advanced gas burners — Instruction manual
Carlin part number MN702G Rev. 03/14/11 – 18 –
Where appliance instructions differ from this manual, follow the appliance instructions.
Adjustment/setup procedure:
Step 1 Pre-set combustion head position and low-fire damper position per
previous instructions (To settings in Table 5).
Step 2 Check gas pilot operation. (See details following.)
Step 3 Set gas pressure (with burner at high fire). (See details following.)
Step 4 Adjust the butterfly valve linkage to match low-fire gas to low-fire
air. (See details following.)
Step 5 Verify operation of burner, appliance, and controls.
Use test instruments
Use combustion test equipment and an accurate manometer
or draft gauge to correctly set the burner as required.
1. Overfire pressure must not exceed the appliance manufacturer’s recom-
mendations. The burner must never be fired at an overfire pressure more
than 0.60 inches w.c.
When the overfire pressure is positive, the maximum burner
firing rate is reduced. The firing rate is also reduced for
altitudes higher than 2000 feet above sea level. See page 3
for rating information.
3. Adjust the burner fuel and air settings using the following procedures.
When adjustment has been completed, the CO
2
(or O
2
) should be within
the ranges in Table 6, at both low fire and high fire.
7. Adjust the burner using test instruments
The settings given in this section are initial settings
only. You must use test instruments to check
combustion, and adjust the burner as necessary,
following the procedures given in the following
pages of this manual. Failure to properly adjust the
burner can result in severe personal injury, death or
substantial property damage.
Step 1
Pre-set burner
If the boiler has been fired recently, do not start the burner
without first purging the combustion chamber using the
burner blower (with manual gas valves closed to prevent gas
flow).
1. Turn service switch OFF.
2. Perform inspections and checkouts on page 16.
3. Verify burner is pre-set according to page 17.
Step 2
Check gas pilot operation
The Model 702GAS uses a gas pilot for ignition of the gas main
flame. The gas pilot is ignited by the burner electrodes.
The butterfly gas valve is factory set to a preliminary setting
of 50% open for low fire, and 100% open for high fire. The
pilot regulator is set for 3.5 inches w.c.
1. Move the burner fuel selector switch to GAS.
2. Set the low-fire switch to low fire.
3. Make sure the gas line has been completely bled and there are no detect-
able gas leaks in the gas piping or components.
4. Turn the service switch to ON.
5. The pilot will usually light the first time once the combustion head assembly
and the low-fire air damper have been pre-set to Table 5 dimensions and
the pilot gas train has been completely purged of air.
6. The pilot flame is approximately 280 MBH, and is large enough to be
heard when lit.
a. If the pilot fails to light, be sure the gas line has been bled properly.
b. If it still fails to light, increase the pilot gas pressure to 4 inches w.c.
To attach a manometer to the pilot gas valve outlet pressure
port, you must turn the burner off, close the gas shut-off valve
and attach the manometer tubing before turning the burner
back on.
c. If the primary control is equipped with a pilot test hold switch, it can be
used to hold the pilot “on” while adjusting pilot gas pressure.
7. Follow the instructions in the primary control instruction manual to check
flame signal. Make sure the flame signal is steady, and greater than the
required minimum for the UV sensor.
8. After pilot operation is checked, allow the burner primary control to start
the burner at low fire.
The burner should operate well enough at low fire to allow
stable flame. If the burner flame is unstable with the burner at
low fire, adjust the butterfly valve linkage slightly to increase
or reduce gas flow. The butterfly valve shaft must be rotated
clockwise to reduce gas flow, counterclockwise to increase
gas flow. Unstable flame usually means slightly more gas is
needed. Adjust the linkage in small movements only, usually
1/8 inch or less per adjustment.
The linkage between the damper motor arm
and the air damper crank is set at the factory,
and should ONLY need adjustment if the damper
motor or the damper rod is replaced. With the burner
in high-fire position, there should be minimal play
in the connecting rod. DO NOT change this linkage
setting.