Crown Boiler BWC Series installation instructions Piping for Special Situations

3)The return piping may be connected into the boiler through the back or sides of the boiler by rotating the drain elbow and routing the return piping through the appropriate knockout.

4)Circulator (Required) - Usually at least two circulators will be required to properly install a BWC Series boiler. See previous section (System Design) for information on sizing the circulators.

5)Expansion Tank (Required) - If this boiler is replacing an existing boiler with no other changes in the system, the old expansion tank can generally be reused. If the expansion tank must be replaced, consult the expansion tank manufacturer’s literature for proper sizing.

6)Fill Valve (Required) - Either a manual or automatic fill valve may be used. The ideal location for the fill is at the expansion tank.

7)Automatic Air Vent (Required) - At least one automatic air vent is required. Manual vents will usually be required in other parts of the system to remove air during initial fill.

8)Manual Reset High Limit (Required by some codes) - This control is required by ASME CSD-1 and some other codes. Install the high limit in the boiler supply piping just above the boiler with no intervening valves. Set the manual reset high limit to 200°F. Wire the limit per Figures 9.1 & 9.2 in the Wiring section.

9)Flow Control Valve (Required) - The flow control valve prevents flow through the system unless the circulator is operating. Flow control valves are used to prevent gravity circulation or “ghost flows” in circulator zone systems through zones that are not calling for heat.

10)Isolation Valves (Recommended) - Isolation valves are useful when the boiler must be drained, as they will eliminate having to drain and refill the entire system.

11)Drain Valve (Required) - The drain valve is installed on the return tee located in the lower vestibule compartment as shown in Figure 8.2.

12)Low Water Cut-off (Required) - The low water cut-off supplied with this boiler must not be removed.

D. Piping for Special Situations

1)Systems containing oxygen - Many hydronic systems contain enough dissolved oxygen to cause severe corrosion damage to an aluminum boiler such as the BWC. Some examples include:

•Radiant systems that employ tubing without an oxygen barrier.

•Systems with routine additions of fresh water.

•Systems which are open to the atmosphere.

If the boiler is to be used in such a system, it must be separated from the oxygenated water being heated with a heat exchanger as shown in Figure 8.13. Consult the heat exchanger manufacturer for proper heat exchanger sizing as well as flow and temperature requirements. All components on the oxygenated side of the heat exchanger, such as the pump and expansion tank, must be designed for use in oxygenated water.

2)Piping with a Chiller - If the boiler is used in conjunction with a chiller, pipe the boiler and chiller in parallel as shown in Figure 8.14. Use isolation valves to prevent chilled water from entering the boiler.

3)Air Handlers - Where the boiler is connected to air handlers through which refrigerated air passes, use flow control valves in the boiler piping or other automatic means to prevent gravity circulation during the cooling cycle.

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