Brochure

132
Selection Guides
Hoffman Specialty
®
Selection Guidelines
Water vents are used in hydronic heating systems and chilled water systems to vent air out of the system. Information
required for sizing and selection.
1. Type of service
Determine the type of service where the vent is to be installed.
a) Radiator Vent
b) Convector Vent
c) Main Vent
2. System operating pressure
Determine the operating pressure of the system. The rated operating pressure of the vent must be higher than
the maximum system operating pressure. When the system pressure exceeds the vent operating pressure rating,
the vent will remain closed and air will remain in the system.
3.
Connection size
Determine the NPT connection size where the vent is to be installed.
4. Capacity
Vent capacity determines the speed that air is initially vented from the system. Once the system is initially filled
with water, very little air should re-enter the system. Thus water vent capacity is relatively unimportant.
5.
Additional features
The Model 792 water vent has a 1/4 NPT outlet in the cover. This allows the installation of a 1/4-inch gate valve
for manual venting or testing of the vent.
Selection Guidelines – Water Vents
Built-in
Model Vacuum
Number Radiator Convector Mains Check Remarks
77 XX Small Systems
78 XXHigh Pressure
79 XXLow Pressure
790 X Small Systems
791 XX Small Systems
792 X Cast Iron Body
508 XX Moisture Type
550 X Air Chamber
Steam and Water Vents(continued)