PB Heat DE Control Descriptions, Adjustment of GAS Pressure Regulator, Checking Burner Input

START-UP PROCEDURES

B.CONTROL DESCRIPTIONS

See Figure 6.1 in Section 6 (Electrical) for locations of these devices.

1.FLAME ROLL-OUT SAFETY SHUT-OFF SWITCH (FLAME ROLL-OUT SWITCH) – A thermally activated switch located between the first burner from the left and the manifold bracket. The flame roll-out safety shut-off switch will sense excessive temperature caused by continued flame roll-out and shut down main burner gas. This is a non-recycling switch that must be replaced once it has been activated and the cause of the roll-out eliminated.

2.PRESSURE SWITCH – A pressure sensing device that is located in the jacket vestibule. This control senses a suction pressure when fan is energized on a call for heat. Switch contacts close allowing control circuit to energize ignition system.

3.LIMIT (AQUASTAT) – A thermally activated, manually adjustable switch located on the left side of the boiler, towards the top and rear. The temperature sensing element is placed in the supply and will shut down main burner gas if the supply water exceeds the preset temperature limit. This is a recycling switch that will automatically reset when the supply water falls below the preset temperature.

4.LOW WATER CUT-OFF (FOR GRAVITY SYSTEMS OR HOT WATER BOILERS INSTALLED ABOVE RADIATION LEVEL) – A level-sensing device (float or probe) located in supply piping near the boiler. If water level in the system drops below the control’s position, it will shut down main burner gas. The control will automatically reset once the water level rises above its position.

C.ADJUSTMENT OF GAS PRESSURE REGULATOR

1.Connect a manometer to 1/8 N.P.T. tapping on gas manifold, set manifold pressure as follows for various gases.

a. Natural Gas 3.5″ W.C. (0.9 kPa)

b.LP Gas . . . . . . . . . . . . .10.0″ W.C. (2.5 kPa)

2.To adjust gas pressure, turn adjusting screw of gas pressure regulator counterclockwise to decrease pressure, clockwise to increase pressure. Refer to Figure 7.2 for location of gas pressure regulator. Replace the cap screw when adjustment is complete.

3.In no case should the final manifold pressure vary more than ±0.3 inches water column (0.07 kPa) from the above specified pressures. Any necessary major changes in the flow should be made by changing the size of the burner orifice spuds.

4.When adjustment is complete, turn off boiler, gas flow and electricity to boiler. Remove manometer connection from valve and plug tapping with plug provided. Turn utilities back on and resume checkout.

D.CHECKING BURNER INPUT

1.Refer to rating label mounted on the jacket top panel to obtain the rated BTU per hour input. In no case shall the input to the boiler exceed the value shown on the rating label.

2.Check input by use of the following formula (PB Heat suggests reading meter for 2 Cu.Ft.

[0.0566 cubic meter]):

U.S. Customary Units:

Input (BTU/Hr.)= 3600 x F x H

T

Where:

3600 – Seconds per hour

F – Cubic Feet of Gas Registered on Meter H – Heat Value of Gas in BTU/Cubic Feet T – Time in Seconds the Meter is Read

SI Metric Units

Input (kW)= 3600 x F x H

T x 3.6

Where:

3600 – Seconds per hour

3.6– Megajoule (MJ) per kilowatt hour (kwhr) F – Cubic Meters of Gas Registered on Meter H – Heating Value of Gas in MJ/Cubic Meter T – Time in Seconds the Meter is Read

3.As an alternative, use Table 7.1a and 7.1b. Use the heating value provided by gas supplier. Use a stopwatch to record the time it takes for 2 cubic feet (0.0566 cubic meter) of gas to pass through the meter. Read across and down to determine rate.

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