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5a Connect Water Boiler Piping

General water piping information:

•System water supply and return piping should be installed and piping connections attached to boiler before erecting jacket or installing controls.

•Do not pipe in through supply and out through return. This creates reverse water flow through boiler that must not be used.

•When three-way valves are used for temperature modulation, install slow-opening (minimum 10-minute) valves and boiler mixing pump to minimize potential of boiler thermal shock. See W-M Bulletin AE-8402.

Install piping:

Install piping as shown in Figure 12 below for single boilers, page 14 for multiple boilers.

Improperly piped systems or undersized piping can contribute to erratic boiler operation and possible boiler or system damage.

1.Connect supply and return piping:

a.Size according to tables below.

1)For unknown flow rates, size piping per Table below, using 20°F. temperature

rise through boiler.

System

 

 

 

 

supply

 

 

(front only)

Cold

Expansion

tank

 

water fill

Check

 

 

 

 

valve

 

Manual

 

Water

 

meter

isolation

 

 

 

valve

Pressure

 

 

 

 

reducing

 

 

valve

Manual

 

(when used)

 

isolation

valve

System return (front or rear)

Part No. 550-141-705

Figure 12 Water Boiler Piping

Recommended Minimum Pipe Sizes

for Unknown Flow Rates*

 

Supply

Return

Boiler

Pipe Size

Pipe Size

Model

A

B

 

 

 

378

2"

2"

478

2-1/2"

2-1/2"

578-678

3"

3"

 

 

 

778-1278

4"

4"

 

 

 

*All piping sizes based on 20°F. temperature rise through boiler.

2)For known flow rates or higher flow rate through boiler, size piping per Table below.

Flow at higher velocities than shown in Table below for pipe size can damage boiler, causing substantial property damage.

Recommended Minimum Pipe Sizes

for Known Flow Rates

Water

Supply

Return

Flow Rate

Pipe Size

Pipe Size

GPM

A

B

 

 

 

Up to 35

2"

2"

36 to 50

2-1/2"

2-1/2"

51 to 77

3"

3"

 

 

 

78 to 142

4"

4"

 

 

 

b. Locate circulator in supply piping.

c. For return piping, use full diameter pipe for 10 times that diameter before making any reduction. For example, a 4-inch return should not be reduced any closer to boiler return tapping than 40 inches.

d. Install system blow-off (drain) valve in lowest part of return piping close to boiler. ASME Size requirements are shown in Table below.

ASME Drain Valve Size

Boiler Model

Valve Size (in.)

 

 

378-478

3/4

578-1178

1

1278

1-1/4

 

 

13

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Weil-McLain 78 manual 5a Connect Water Boiler Piping, General water piping information, Install piping
Page 12 Page 14

78 specifications

The Weil-McLain 78 is a high-efficiency, versatile cast iron boiler that has been a staple in residential and commercial heating applications for decades. Renowned for its durability and performance, the boiler is designed to provide reliable heat while maintaining efficiency and minimizing energy consumption.

One of the main features of the Weil-McLain 78 is its cast iron construction. This material is not only known for its longevity but also for its excellent heat retention properties. The cast iron sections allow for a slow, steady heat release, ensuring that spaces remain warm and comfortable. The boiler is built to withstand the rigors of everyday use, making it ideal for both home and business environments.

In terms of technology, the Weil-McLain 78 incorporates an advanced combustion system that optimizes fuel usage. This efficient burning process not only conserves energy but also contributes to lower utility bills for users. Moreover, the boiler is designed to work well with natural gas or propane, giving homeowners and businesses flexibility in fuel choices.

Another characteristic contributing to the Weil-McLain 78’s reputation is its efficiency ratings. With a rating of 83% AFUE (Annual Fuel Utilization Efficiency), this boiler stands out in its class. This efficiency not only reduces carbon emissions but also enhances overall operational effectiveness, allowing for significant energy savings over time.

The Weil-McLain 78 is also designed for ease of installation and maintenance. Its compact design allows it to fit in tighter spaces, and the accessibility of key components simplifies routine servicing. The unit comes with a multitude of options for controls and accessories, ensuring adaptability to various heating systems.

Furthermore, Weil-McLain places a strong emphasis on safety features. The 78 model incorporates multiple safety controls, including a temperature limit switch and an automatic shut-off system. These features help prevent overheating and provide peace of mind for users.

In conclusion, the Weil-McLain 78 combines robust construction, advanced technology, and efficiency, making it an excellent choice for various heating needs. Its reputation for reliability, comfort, and safety has positioned it as a leader in the boiler market for both residential and commercial applications. With the Weil-McLain 78, users can enjoy consistent warmth and comfort for years to come, backed by a trusted name in heating solutions.
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