The Caleffi 337221A is a Manual air vent with 1/4" NPT Threaded connections. Installed at radiators and system high points, it releases trapped air when its metal-seat vent screw is opened by hand.
Best for manual air release at radiators and system high points.
Specifications sourced from Caleffi North America technical literature. Last reviewed July 2026.
Key Features
Manual Metal-Seat Vent
Durable metal seat with an adjustable outlet so discharge can be directed away from walls and finishes during venting.
Technical Specifications
| Function | Manual air vent |
| Series | Caleffi Manual |
| Connection | 1/4 in NPT |
| Body material | Composite/Brass |
| Maximum operating pressure | 150 psi |
| Medium temperature range | 40 - 212 °F |
| Operation | Manual |
| Shipping Weight | 0.3 lb |
Documentation
Design Resources
Related Products
- Caleffi 502420 : ROBOCAL Air Vent 1/4" Metric Thread
- Caleffi 502630 : ROBOCAL Air Vent 3/8" Metric Thread
- Caleffi 502640 : ROBOCAL Air Vent 1/2" Metric Thread
- Caleffi 502015A : MINICAL Air Vent 1/8" NPT Threaded
Frequently Asked Questions
What does Caleffi 337221A do?
Caleffi 337221A is an air vent in the Caleffi Manual range. It is opened by hand to release trapped air from radiators and high points, helping prevent air pockets, noise and corrosion.
What connection does Caleffi 337221A use?
It is supplied with 1/4" NPT Threaded connections. Other sizes and connection styles in the Manual range are listed under Related Products.
Is Caleffi 337221A automatic or manual?
It is a manual air vent, opened with a key or screwdriver to release trapped air. It does not vent continuously; an automatic vent is the alternative where unattended venting is wanted.
What are the pressure and temperature limits of Caleffi 337221A?
Maximum operating pressure is 150 psi, over a medium temperature range of 40 - 212 °F.
What is the warranty on Caleffi 337221A?
Caleffi covers this product under its standard two-year limited warranty against defects in material and workmanship from the date of shipment. ZOT Supply is an authorized Caleffi distributor.
- Product Type:
- Air Vent
- Series:
- Manual
- Connection Type:
- NPT Threaded
- Connection Size:
- 1/4 in
- Operation:
- Manual
- Max Operating Pressure:
- 150 psi
- Medium Temperature Range:
- 40 - 212 deg F
- Body Material:
- Composite/Brass
