National Oilheat Research Alliance 7 Figure 7 Air Separator These devices offer enhanced air separation characteristics. They do not require a run of straight pipe on the inlet side and their design enables them to capture and remove smaller bubbles. They should be placed on the supply pipe as close to the boiler as is possible (air turns to bubbles more easily in hot water.) Figure 7. 5 Air vents—These devices are installed in the system piping to remove air bubbles. There are two types of air vents: Automatic air vents Automatic air vents have a float which lowers and opens a spring loaded venting valve to purge air from the system. When Figure 8 the air is vented, the float rises and closes the vent. When using automatic air vents, the system pressure at all vent locations should always be at least 3 psi above atmospheric pressure to prevent air from being pulled into the system. Manual air vents Manual air vents are normally installed on individual terminal units and are used to remove air during system startup and when troubleshooting air problems in the system. 6Pressure reducing valve (PRV) Figure 8. PRV’s serve two functions. First, they reduce the home’s higher water pressure to the lower pressure required by the heating system. The water pressure in most homes is typically from 40 to 80 psi, depending on whether the water is supplied from a well (lower pressure) or is city-supplied (higher pressure). The PRV also fills the system with enough water that the water at the top of the system is under sufficient pressure to vent all of the air in the system while allowing water to circulate. Air Separators
NORA Advanced Hydronics
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