Crown Boiler BWC Series Method 2 Primary/Secondary Piping Boiler in Primary Loop

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Method 2: Primary/Secondary Piping - Boiler in Primary Loop

This method can be used in heat-only applications as shown in Figure 8.8 or with an indirect water heater as shown in Figure 8.9. Like Method 1, this method relies on primary/secondary pumping to ensure that the required flow is always maintained through the boiler. In this system, the flow rate through the boiler is completely independent of the flow rate through the heating zones. The boiler is installed in the heating system primary loop as shown.

This system provides more accurate control of the water temperature entering the heating zones as the number of zones calling for heat changes. When this piping method is used, the boiler control is set to provide the highest supply temperature required by any heating zone and some other means, such as 3-way valves, are used to control the water temperatures required by any zones requiring lower temperature water. This system is only recommended when the primary loop (shown bolded in Figure 8.10b) is to be constructed as part of the boiler installation and can be constructed as shown. Also, if the boiler is to accurately control the temperature entering each secondary loop, the flow rate in the primary loop must be at least as great as the sum of the flows through all secondary loops.

Use the following guidelines to ensure that boiler will have the required flow shown in Table 8.1 regardless of the flow in the heating system.

1) Heating System Secondary Loop Piping - The heating system secondary loop piping is shown in Figure 8.10a. Size each secondary zone circulator and piping to obtain the design flow rate for that zone as you would on any other heating system. When the heating zone requires a water temperature below that to be controlled by the boiler, provide a mixing valve or blending station for that zone. In order to keep the flow rates in the primary and secondary loops independent of each other, provide at least 8 diameters of straight pipe upstream of the first secondary tee and 4 diameters downstream of the second secondary tee.

2) Heating System Primary Loop (“Boiler Loop”) – The primary loop (“boiler loop”) piping is shown bolded in Figure 8.10b. All piping in this loop must be the size shown for the boiler in Table 8.5, column a. To size the circulator:

a) Starting at the boiler, trace a path through the heating system primary loop from the boiler supply connection to the boiler return connection, counting fittings and straight pipe as you go. Where the primary loop breaks into parallel paths, follow just one of these paths (it doesn’t matter which one). Do not count the secondary connection tees, unions, or the fittings supplied with the boiler (these have already been accounted for).

b) Using Table 8.7, find the equivalent lengths of all fittings counted in (a). Total these equivalent lengths and add them to the total length of straight pipe measured in step (a). The result is the total equivalent length of the primary loop.

c) Using Table 8.5, find the boiler size being installed and select a boiler primary circulator that shows a “maximum equivalent length” (column d) in excess of the total equivalent length calculated in Step b.

3) Indirect Water Heater Loop Piping (If Indirect Water Heater is Used) – All piping must be the size shown in Table 8.6, column (a). If the indirect water heater connections are smaller than the pipe size called for in column (a), reduce the pipe size at the indirect water heater connections. To size the circulator:

a) Count all fittings in the planned Indirect Water Heater Loop (the indirect water heater loop consists of the bolded piping in Figure 8.10c). In doing so, you will be counting some piping and fittings which are common to the heating system primary piping (the “boiler loop”) and which were counted in Step 2a above. Do not count the elbows or fittings supplied with the boiler.

b) Using Table 8.7, find the equivalent lengths of all fittings in the indirect water heater loop. Total these equivalent lengths and add them to the total length of planned straight pipe in the indirect water heater loop. The result is the total equivalent length of for the indirect water heater loop.

c) Using Table 8.6, find the boiler size being installed and select an indirect water heater loop circulator that shows a “maximum equivalent length” (column f) in excess of the total equivalent length calculated in Step b.

Method 3: Direct Connection to Heating System (Generally NOT Recommended)

The BWC can be connected directly to the heating system as is done with conventional boilers (Figure 8.11). If this is done, the flow rate through the boiler will equal the flow rate through the system. The flow rate through the system must therefore always remain within the limits shown in Table 8.1. For this reason, the pressure drop through the entire system must be known, added to the boiler pressure drop, and a circulator selected which will provide the required flow at the total calculated pressure drop.

This method is generally not recommended because it is often very difficult to accurately calculate the pressure drop through the system. In replacement installations, it may be impossible to get an accurate measurement of the amount of piping and number of fittings in the system. In addition, if the system is zoned, the system flow may drop well below the minimum required when only one zone is calling for heat.

The one advantage to this method is its installation simplicity. It may make sense to use this method when the boiler is to be installed with a new single zone system having a low-pressure drop. Pressure drop curves for the BWC Series boilers are shown in Figure 8.12. Calculation of the system pressure drop, and selection of the circulator, must be performed by someone having familiarity with pressure drop calculations, such as an HVAC engineer.

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Contents BWC Series Page VII II Specifications Product DescriptionIV Locating the Boiler III Before InstallingMinimum Clearance To Combustible Material Air for Ventilation Page Vent System Design VI VentingHorizontal Direct Venting Vent Options 1,2 2a Summary of Horizontal Venting Options 3c Positioning Vent Terminal Under Overhangs Vertical Direct Vent System Vent Options 6 2b Summary of Vertical Venting Options VENT/ AIR Intake Fitting Equivalent Length Removing an Existing Boiler From a Common Chimney Vent / Intake System Assembly7a STAR-34 Connection to Vent Collar Z-VENT III Connection to Vent Collar SAF-T Vent Ezseal Connection to Vent Collar 10 Fasnseal Connection to Vent Collar 11 Condensate Piping Arrangement Gas Connection To Boiler VII Gas PipingSystem Design General System Piping PrecautionsViii System Piping Method 1 Primary/Secondary Piping Boiler in Secondary Loop Piping Method #1 Heat Only 4a Piping Method #1 Secondary Loop Piping Shaded Pipe and Circulator Sizing for Boiler Loop Fitting Equivalent Lengths Method 2 Primary/Secondary Piping Boiler in Primary Loop Piping Method #2 Heat Only 10a Piping Method #2 Secondary Loop Piping Bolded Page Flow GPM Piping for Special Situations 14 Chiller Piping IX Wiring Wiring Connections Diagram Ladder Diagram Page Start-up and Checkout BWC Series Lighting and Operating Instructions For Your Safety Read Before LightingBWC Burner Typical CO2/O2 Combustion Readings Gas Valve DetailPage XI Operation Normal Display In Standby ModePage 170 First Digit Boiler Status Boiler StatusOutdoor Reset Curve Continuously XII. Service and MaintenancePage No Error Code Displayed XIII. TroubleshootingCode Condition Possible Causes Soft Lockout Codes DisplayedHard Lockout Codes Displayed XIV Parts BWC Replacement Parts List TBD Page Page Page Page Ignition Electrode Gasket, 5mm 240011 Page BWC Replacement Parts List Page Page Page Page Page PN 980040 BWC 08/05

BWC Series specifications

The Crown Boiler BWC Series is a modern choice for heating needs, renowned for its efficiency and robust design. This series offers a range of residential and light commercial heating applicabilities, ensuring both comfort and reliability for users.

One of the standout features of the BWC Series is its efficiency. Crown Boilers utilize advanced technologies to maximize energy output while minimizing fuel consumption. With an AFUE (Annual Fuel Utilization Efficiency) rating often exceeding 90%, users can expect significant cost savings on their energy bills over time.

The BWC Series employs a high-quality, stainless steel heat exchanger, which not only enhances performance but also extends the lifespan of the boiler. This heat exchanger is designed to transfer heat efficiently, ensuring that the maximum amount of energy from the fuel is converted into usable heat. Additionally, the design helps to prevent corrosion and maintain system integrity over years of usage.

For technological advancements, the BWC Series incorporates a modulating gas valve which allows for precise control over the boiler's operation. This feature enables the system to adjust its output based on the heating demands of the home, resulting in improved energy efficiency and consistent comfort levels. Moreover, this modulating technology reduces the frequency of cycling, thereby prolonging the lifespan of the unit and minimizing wear and tear.

Another characteristic of the Crown Boiler BWC Series is its user-friendly interface. The boiler is equipped with a simple control panel that allows for easy monitoring and adjustment of settings. This accessibility is essential for users who want to manage their heating system without the need for extensive technical knowledge.

In terms of installation and maintenance, the BWC Series is designed with convenience in mind. Its compact footprint allows it to fit comfortably in a variety of spaces, making it an ideal choice for homes with limited installation areas. Additionally, Crown Boiler's commitment to high manufacturing standards ensures that the units require minimal maintenance, providing peace of mind to homeowners.

Overall, the Crown Boiler BWC Series is an excellent solution for those seeking efficient, reliable heating. Its combination of advanced technology, quality construction, and user-friendly design makes it an attractive option for any residential or light commercial application. Whether replacing an old system or installing a new one, the BWC Series delivers comfort and performance that can be depended upon.
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