Chapter 4 Best Boiler Piping Practices Purge valve—this location enables the technician to quickly remove air from the entire system. By closing the isolation valve(s), manually closing the zone valves one at a time and then opening the purge valve, water can be forced to flow through, and completely fill, each zone. Isolation valve—this valve enables quick service of system components and isolates the purge valve from the pressure reducing valve, forcing water to flow through the system and back to the purge valve. This should be a gate or ball valve; globe valves should NOT be used. Air separator—when using a diaphragm type tank, an automatic air vent should be installed in the top tapping. Always double check Figure 3 installation instructions to verify the length of straight piping required on the inlet side of the separator. Air scoops will NOT function properly if the laminar piping is not at least 18". Figure 3. National Oilheat Research Alliance 33 In addition to proper sizing of the boiler, piping, circulators and expansion tank, for a heating system to operate properly, it is important that the various components are installed in the proper configuration. Figure 1 on following page. Unless the manufacturer recommends differently, the following piping arrangement are recommended: Relief Valve—a properly sized relief valve must be installed in the correct location and a metal “drip tube” installed that is the same size as the valve’s outlet. This must be piped to a Figure 2 safe location to prevent scalding if the valve discharges. There should NEVER be a valve between the boiler and relief valve or in the discharge line. Figure 2.
NORA Advanced Hydronics
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