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.VENT SAFETY SHUT-OFF SWITCH (SPILL SWITCH) – A thermally activated, manually resetable switch located in the draft hood relief opening. If venting system becomes partially or totally blocked, the vent safety shut-off switch will sense excessive temperature caused by flue products exiting the draft hood relief opening and shut down main burner gas.

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.Using the manometer setup installed in part 7A, set manifold pressure as follows for various gases.

a.Natural Gas . . .3.5″ Water Column (0.9 kPa)

b.LP Gas . . . . .10.0″ Water Column (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 7.3 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. GAS FLOW

D.ADJUSTMENT OF PILOT GAS FLOW

To maximize thermocouple life, particularly on natural gas installations with gas supply pressures above 9″ W.C. (2.2 kPa), reduce the pilot gas flow.

WARNING

Turn off all electric power to the appliance.

Turn Gas Control Knob to “Pilot” position as shown in Figure 7.3.

1.Locate and remove the pilot adjustment cap screw using Figure 7.3.

2.Remove pilot observation port cover on base front panel.

3.Turn the pilot adjustment screw clockwise until the pilot flame extinguishes. Then increase the pilot flow just to the point that the gas valve holds in when relighting the pilot per steps 9 and 10 of Lighting Instructions in Figure 7.5 (turn screw no more than an 1/8 turn).

4.Turn on electric power to the appliance.

NOTICE

The first few turns of the adjustment screw may not cause any change in the pilot flow. Subsequent partial turns of the adjustment screw may have a great impact on pilot flow.

5.Turn Gas Control Knob to “On” position per the Lighting Instructions in Figure 7.5.

6.Verify pilot remains lit after shutdown from a boiler “ON” cycle of at least ten minutes. If pilot extinguishes, follow Lighting Instructions in Figure 7.5 and again slightly increase pilot flow.

7.Make a final slight increase in the size of the pilot to ensure sufficient pilot signal under all operating conditions, just to the point that you observe a slight increase in the size of the flame (no more than an 1/8 turn).

8.Replace adjustment cap screw and observation port cover.

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PB Heat MI/MIH series manual Control Descriptions, Adjustment of GAS Pressure Regulator, Adjustment of Pilot GAS Flow
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MI/MIH series specifications

The PB Heat MI/MIH series represents a significant advancement in the realm of cast iron boilers, engineered for high efficiency and reliable performance in both residential and light commercial applications. Crafted with exceptional care, these boilers combine traditional design elements with modern technologies to optimize heating capabilities.

A standout feature of the MI/MIH series is its construction. Made from high-quality cast iron, the boiler body is built to withstand the test of time while providing superior heat retention. This material ensures consistent heating over extended periods, reducing the need for frequent cycling on and off, which enhances overall efficiency.

The MI/MIH series incorporates a versatile design that accommodates various heating systems, including hot water heating and steam applications. This flexibility is a key selling point, as it allows homeowners and business operators to tailor their heating solutions to specific needs. Additionally, the units are compatible with multiple fuels, including oil and natural gas, making them a practical option for diverse environments.

Efficiency is another critical component of the MI/MIH series. The boilers are designed to operate at high efficiency levels, often surpassing industry standards. Many models in this series feature advanced combustion technology that maximizes fuel use while minimizing emissions. This not only supports environmental sustainability but also results in lower utility bills for consumers.

The MIH variant, specifically, offers additional features like an integrated secondary heat exchanger, which enhances heat transfer and further improves efficiency. Maintenance is made simple, thanks to thoughtful engineering. With large clean-out ports and easily accessible components, routine maintenance can be performed with ease, reducing downtime and extending the boiler's lifecycle.

Moreover, safety is a fundamental aspect of the MI/MIH series. These boilers include multiple safety features, such as automatic safety shutdown systems and built-in pressure controls, ensuring safe operation under various conditions.

In summary, the PB Heat MI/MIH series cast iron boilers stand out due to their durability, versatility, high efficiency, and robust safety features. These models cater to a range of heating requirements, making them a reliable choice for those seeking long-term heating solutions that prioritize both performance and sustainability. As homeowners and businesses look for dependable and efficient heating options, the MI/MIH series remains a prominent player in the industry.
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