IBC VX Series Installation & Operating Manual page 50

Fluid fill is most often accomplished by using a boiler regulator and fill valve set at 12 psig or
more, with the appropriate backflow prevention device as required by local code. This is
acceptable in areas where municipal water or well water has been treated and filtered to remove
excessive minerals and sediment, and water chemistry is known to be suitable for closed loop
hydronic systems. In areas where water quality is in question, or when chemical treatment or
glycol is required, other options should be considered. Follow the applicable codes and good
piping practice.
Warning
Close the fill valve after any addition of water to the system, to reduce risk of water
escaping.
Today there are a number of boiler feed and pressurization devices on the market that may be a
better choice than a raw water fill from the mains. When regular maintenance requires relief
valve blow-off, the discharge may be directed back into the pressurization appliance for
recycling of boiler fluid and chemicals back into the system. In buildings that may be
unoccupied for long periods of time, pressurization appliances are useful to prevent flood
damage should leakage occur from any component in the system. An additional benefit is that
backflow prevention devices are not required when using these devices.
Do not place any water connections above the boiler to avoid damage to the fan and controls. If
needed, create a shield over the top of the cover, but allow clearance for airflow and service
access.
3.11.2.1 Primary-Secondary piping
For best results, use a primary/secondary piping system, with a pumped boiler loop using 1" or
1¼" piping. Primary/Secondary piping ensures adequate flow and de-couples Δ°T issues (boiler
vs. distribution). Aim for a 20° to 30° F Δ°T across the heat exchanger at high fire (there is a
boiler protection throttle fence limiting the Δ°T to 40°F).
For the model, the heat exchanger head is only 1.5' at 4 US gpm and approximately 4' at
VX 110
10 US gpm. To ensure adequate water flow through the boiler under high-head / single zone
space heating conditions, a pressure activated bypass or other means of bypass must be used
on any load where the flow rate might drop below minimum requirements.
Check valves or thermal traps should be used to isolate both the supply and return piping for
each load - to avoid thermal siphoning and reverse flow.
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Section: Installation