ELECTRICAL

Figure 6.2: Wiring and Connection Diagram – Standing Pilot (Continuous Ignition)

D.SEQUENCE OF OPERATION

1.Standing Pilot (See Figure 6.2 above)

a.The vent damper is continuously powered. On a call for heat, limit relay R is energized, which energizes:

the circulator (when used) through contact R1, and

the vent damper operator through contact R2, provided that the high-limit switch is closed.

The vent damper operator opens the damper.

b.Once the damper is proven open, the gas valve energizes, provided that all of the following conditions are met:

the pilot thermocouple is proving flame

the blocked vent switch is closed, and

the flame rollout switch is closed.

Pilot flame is monitored through the pilot thermocouple. If pilot flame is lost during a call for heat, main and pilot gas flow will be shut off. The valve must then be manually reset by following the Lighting Instructions mounted on the jacket panel and included in Section 7 of this manual.

c.When the call for heat ends:

Limit relay R de-energizes, which opens contacts R1 and R2.

The circulator shuts down.

The gas valve de-energizes.

The vent damper closes.

d.If temperature exceeds limit setting, main burners shut off and circulator continues to operate.

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PB Heat MI/MIH series manual Sequence of Operation

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.