14
NOTE: The Btu/hr input values in Table 4 show the approximate hourly input of the burner for the various drill bit sizes shown. To
determine the actual input of the burner by using the gas meter, follow these steps:
1) Turn off all other gas appliances.
2) The hand on the dial with the lowest cubic feet value (fastest revolving dial) should be clocked for one complete revoluti on.
3) Divide 3,600 by the time in seconds for one complete revolution and multiply by the dial value (1, 2, or 5 cubic feet depending
on size of meter.)
4) Multiply this by the heating value of the gas to obtain the input to the burner in Btu per hour.
EXAMPLE: Time in seconds for one complete revolution of dial is 72. 3,600 divided by 72 is 50, 2 cubic foot was timed therefore
50 x 2 is 100. Multiply 100 by heating value of gas which is 1,075 for natural gas; and this will give you an input of 107,500 Btu/hr
(31.51 Kw). Use a heating value of 2500 for LP gas.
IMPORTANT:
The minimum gas supply pressure is 4.5” w.c. (1121Pa) for natural gas and 11.0” w.c. (2740Pa) for L.P. gas;
The maximum gas supply pressure is 10.5” w.c. (2615Pa) for natural gas and 13” w.c. (3238Pa) for L.P. gas.
Valve is rated for 0.5 PSI or 14” w.c. Over pressurizing valve may cause damage to the valve.
CHANGING THE ORIFICE
When leaving the factory each stock burner is sent out firing close to the minimum Btu/hr rating.
To increase the Btu/hr rating (increase the heating output) the orifice must either be changed or drilled out to the correct
size. To determine drill bit size for required rate, see Table 4.
Each burner is sent out with two orifices. A blank orifice is hanging from the gas valve in a plastic bag. The second
(minimum rate) orifice is installed in the burner in the orifice holder.
Before replacing the orifice, gas supply and power must be shut off. To replace the orifice locate and remove the two nuts
that hold the orifice holder and gas pipe train to the back of the burner (Figure 7).
FIGURE 7: ORIFICE HOLDER/GAS PIPE TRAIN NUT LOCATION
TIP:
Loosen the nut to the end of the stud and remove the second nut. This will help prevent the venturi from
sliding down the air tube when reinstalling the gas train.
Summary of Contents for P250 series
Page 35: ...35 FIGURE 23 WIRING DIAGRAMS FOR GAS BURNER WITH DIRECT IGNITION FENWAL...
Page 36: ...36 FIGURE 24 WIRING DIAGRAMS FOR GAS BURNER WITH ELECTRONIC PILOT HONEYWELL...
Page 37: ...37 FIGURE 25 WIRING DIAGRAMS FOR GAS BURNER WITH ELECTRONIC PILOT NO T STAT...
Page 38: ...38 FIGURE 26 WIRING DIAGRAMS FOR GAS BURNER WITH ELECTRONIC PILOT FENWAL...
Page 46: ...46 NOTES...
