Automatic air vent Termojet DN15 (1/2")

Automatic air vent Termojet TJ4F15 — a compact float valve for continuous removal of free air from the heating system. Installed at the highest points of the pipework, where air pockets naturally accumulate, and removes them without any manual intervention — 24 hours a day, 7 days a week.

Technical Specifications

How It Works

Inside the body is a float attached to a lever. While there is water in the chamber, the float holds the valve closed. When an air pocket enters the body, the float drops and opens the discharge port: air escapes to the outside. As soon as water returns, the float closes the valve. The cycle occurs automatically, without batteries or adjustments.

Where and How It Is Used

• High points of pipework. Air naturally rises — that is exactly where the air vent is most effective: at pipe loops, beam bypasses, and high points of the distribution network.
• Radiator assemblies. Instead of a manual Maevsky valve — an automatic equivalent: no need to come by every year and bleed air manually.
• Underfloor heating manifolds. Installed on the manifold of the floor circuit, the air vent removes air during initial filling and during operation.
• After system flushing. When filling with fresh water, a large amount of dissolved gas remains in the pipework — the automatic air vent discharges it during the first hours of operation.
• Initial filling of a new system. During installation it ensures rapid purging of air pockets without manual manipulation at each point.

Advantages of Termojet TJ4F15

• Simple installation: screw into the DN15 threaded fitting — done, no further maintenance required.
• No power supply — the mechanical float principle guarantees operation even during power outages.
• The brass body is corrosion-resistant and compatible with standard heat-transfer fluids.
• If protection against micro-bubbles circulating in the system is required, consider Termojet air separators: they operate on a fundamentally different level, removing even invisible micro-bubbles through a coalescent insert.

Frequently Asked Questions

How does an automatic air vent differ from a Maevsky valve?
The Maevsky valve is a manual device: to bleed air, you need to approach it, place a container and open the valve. The automatic air vent does this on its own, continuously. However, both devices remove only free (large) air. Micro-bubbles — small bubbles under 1 mm that circulate in the system and cause noise and reduced efficiency — are removed only by an air separator with a coalescent insert.

At which points should the air vent be installed?
At the highest points of the system — where air naturally accumulates. These can be the upper loops of the pipework, points above beams or floor slabs, as well as directly on manifolds. If the system has several independent high points — install one at each of them.