Crown Boiler FWZ Series, Руководство по установке

Страница: 24 / 56

22
FIGURE 8.3: INDIRECT WATER HEATER BOILER SIDE PIPING
B. Piping for Special Situations
Certain types of heating systems have additional requirements. Some of the more common variations follow:
1) Indirect Water Heaters - Figure 8.3 shows typical indirect water heater piping. Boiler piping is the same as for any two zone
system. Figure 8.3 shows circulator zoning, which is usually preferred for indirect water heaters. Size the circulator and
indirect water heater piping to obtain the boiler water flow through the indirect water heater called for by the indirect water
heater manufacturer.
2) Large Water Volume Systems - The piping shown in Figure 8.4 will minimize the amount of time that the boiler operates
with return temperatures below 135°F on these systems. A bypass is installed as shown to divert some supply water directly
into the return water. The bypass pipe should be the same size as the supply. The two throttling valves shown are adjusted so
that the return temperature rises above 135°F during the first few minutes of operation. A three-way valve can be substituted
for the two throttling valves shown. A bypass can also be used to ensure that the minimum flow requirement in Table 8.0 is
met.
3) Systems Containing Oxygen - Many hydronic systems contain enough dissolved oxygen to cause severe corrosion damage to
a cast iron boiler such as the FWZ. 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 8.5. 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.
4) 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.