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Finned copper tube gas boilers & water heaters – Boiler Manual
21
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CHECKING & ADJUSTMENTS
Pilot Adjustment
Th e pilot burner fl ame should envelope
3/8 in to 1/2 in
,
9.5 mm to 12.7 mm
of the fl ame sensing probe, Figure 11. To
adjust the pilot the following steps must be taken:
1. Remove the pilot gas pressure regulator cap.
2. Turn the pressure regulator adjustment screw clock-wise to
decrease the fl ame and counterclockwise to increase it.
3. Replace the pressure regulator adjustment screw cap.
Figure 11
Pilot Flame Adjustment
Gas Pressure Adjustment
Th e maximum inlet gas pressure listed on the rating
plate must not be exceeded or damage to the boiler/
water heater may occur!
Th e minimum supply pressure listed on the rating plate is for input
adjustment.
NATURA
L GAS: Optimum results are obtained when the boiler/
water heater is operated at its full input rating, with
3.8 in to 4.2 in
,
96.5 mm to 106.7 mm
WC of manifold pressure. Th e manifold
pressure should not vary outside this range. Th e gas valve pressure
regulator has been preset at the factory. If adjustment is necessary the
following steps must be followed:
1. Att ach a
20 in
,
508 mm
WC manometer to the tap on the
manifold.
2. Remove the regulator adjustment screw cap from the gas
regulator. On systems that do not use a separate gas regulator,
remove the adjustment screw cap from the gas valve body on
the valve closest to the gas supply piping.
3. Rotate the regulator adjustment screw clockwise to increase the
manifold pressure, counterclockwise to decrease it.
4. Replace the regulator adjustment screw cap and manifold pressure
tap plug.
Never force the regulator adjustment screw beyond
the stop limits or damage to the regulator will occur!
PROPANE GAS: A manifold pressure of
11 in
,
279 mm
WC
must be maintained for proper operation of the boiler. If the manifold
pressure is off by more than 5% adjust it according to steps 1 through
4.
Input Rate, Natural Gas
Gas appliances are rated based on sea level operation with no
adjustment required at elevations up to
2000 ft
,
610 m
. At
elevations above
2000 ft
,
610 m
, input ratings should be reduced
by 4% for each additional
1000 ft
,
305 m
.
Check the input rate as follows:
1. Turn off all other gas appliances that use the same gas meter
as the boiler/water heater.
2. Call your gas supplier and ask for the heating value of the gas.
3. Start the boiler/water heater and let it run for 15 minutes.
4. Using the gas meter and a stopwatch, clock the time that it takes
to burn
10 ft
3
,
0.28m
3
of gas and divide this time by 10.
5. Insert the heating value and the time, in seconds, into the formula
below.
6. Input = (heating value, Btu/hr)(3600)/(time, seconds)
7. If the computed rate deviates by more than 5% from the rated
input value of the unit adjust the manifold pressure accordingly.
DO NOT adjust the manifold pressure by more than 5%. If a
proper rate cannot be maintained without adjusting the manifold
pressure beyond the 5% limit, the main burner orifi ces must
be replaced. If the input rate is too low, go to the next larger
size of main burner orifi ces. If the input rate is too high, go to
the next smaller size.
Never increase the input to the boiler/water heater
above that for which it is rated. Doing so can cause
premature failure of the unit!
CONTROL DESCRIPTION
Low Water Cutoff
If the boiler is to be installed above radiation or if required by other
codes or regulations, install a low water cutoff in appropriate piping.
If installed, ensure that the low water cutoff device(s) function
properly. Test in accordance with the manufacturer’s instructions
included with the device(s).
Boiler Thermostat
If a thermostat is to be used to control the boiler always follow the
instructions included with the thermostat. Proper location of the
thermostat will ensure effi cient trouble-free operation of the boiler.
Mount the thermostat to an inside wall at a height approximately
fi ve feet above the fl oor.
Avoid placing the thermostat in areas that will not provide an accurate
measurement of the room temperature. Locating the thermostat
behind a door, in an alcove, close to a source of thermal radiation
or in a draft y area will cause poor or sporadic heating.
For a thermostat that employs an adjustable heat anticipator, adjust
the anticipator to match the current measured in the thermostat
circuit. An increased anticipator sett ing may be necessary if the unit
cycles frequently. If the room temperature over-shoots the thermostat
sett ing, reduce the anticipator sett ing.
RIOM-48
