Checking And Adjusting Input - A.O. Smith HW 300 Installation & Operation Manual

CHECKING AND ADJUSTING THE INPUT
1. Follow steps 1 thru 6 of the OPERATING INSTRUCTIONS.
2. Attach a pressure gauge or a manometer to the manifold
pressure tapping and refer to table 10 for correct manifold
pressure.
3. Follow steps 7 thru 11 of the OPERATING INSTRUCTIONS.
4. Use this formula to "clock" the meter. Be sure that other gas
consuming appliances are not ON during this interval.
3600 x H = Btuh
T
Btuh = The approximate actual input rate.
T = Time in seconds to burn one cubic foot of gas.
H = Heating value of the fuel gas in Btu per cubic foot of gas.
EXAMPLE:
T = 9.0 seconds/ft
3
H = 1050 Btu/ft (natural gas)
3
Btuh = ?
Gas flow through meter:
3600 x 1050 = 420,000 Btuh
9.0
Small changes in the input rate may be made by adjusting the
manifold pressure, see GAS PRESSURE REGULATORS. Under
no circumstances should you exceed the maximum input rate
for the boiler given in table 2 on page 6.
5. Repeat steps 1 thru 6 of the OPERATING INSTRUCTIONS.
6. Remove the pressure gauge or manometer from the manifold
pressure tapping. Replace the screw-in plug in the manifold
pressure tap.
7. Repeat steps 7 thru 11 of the OPERATING INSTRUCTIONS.
The boiler will resume normal operation.
When the boiler is operating at full capacity, or full gas input,
it should consume 1 cu. ft. of gas in approximately the time
indicated in table 10.
CONSUMPTION RATE
(Refer to Operating at Full Input or Full Capacity)
Time to Consume 1 cu. ft. of gas (seconds)
Heating
Type Gas Value
HW-
Btu/Ft.
300
Natural 1050 12.6
Propane 2500 30.0
UNDER NO CIRCUMSTANCES SHOULD THE GAS INPUT
EXCEED THE INPUT SHOWN ON THE BOILER MODEL AND
RATING PLATE. OVERFIRING COULD RESULT IN DAMAGE
OR SOOTING OF THE BOILER. Minor variances from input
on rating plate can be corrected by adjustment of gas pressure
regulators described in GAS PRESSURE REGULATORS section
of this manual.
The inlet gas pressure must not exceed or be less than the values
shown on rating plate.
41
TABLE 10.
HW- HW- HW- HW-
399 420 520 610
9.5 9.0 7.3 6.2
22.6 21.4 17.3 14.8
IMPORTANT
HW-
670
5.7
13.4