Air separator Termojet DN20 (3/4") 110°C/10bar TJ-CA-DN20

TJ-CA-DN20 is an air microbubble and dissolved gas separator for DN20 heating systems. It is installed immediately after the boiler on the supply pipe — at the hottest point in the system, where gas is most actively released from the heat-transfer fluid. It continuously removes microbubbles that cannot be eliminated by a standard air vent or a manual bleed valve.

Technical Specifications

How It Works

The heat-transfer fluid passes through the separator's expanded chamber — the flow velocity drops. Inside, a honeycomb insert of welded copper wires is placed: its developed surface captures microbubbles. The bubbles adhere to the wire, coalesce into larger ones, and rise to the automatic air vent on the cap, from where they are discharged to the outside. This process takes place continuously during system operation — without intervention and without maintenance of the insert. Pressure drop across the separator is minimal.

Applications

• Gas or solid-fuel boiler up to 15–20 kW. DN20 is the standard connection diameter for small boilers and water heaters. The separator is installed immediately after the boiler on the supply pipe.
• New system from first start-up. When filling the system, the heat-transfer fluid always contains dissolved gas. The separator removes it within the first hours of operation — radiators heat up evenly, without bubbling noise.
• Old system with chronic air locks. If you constantly have to bleed radiators with a manual bleed key — the problem lies in circulating microbubbles that an ordinary bleed valve will never clear. The air separator solves this problem permanently.
• Underfloor heating system. Air in the floor circuit obstructs heating of individual zones — the separator removes it and equalises the temperature across the entire floor area.

Advantages

• Removes microbubbles (<1 mm) invisible to the eye — those that a manual bleed valve never vents.
• Continuous action without maintenance — the honeycomb insert requires no cleaning or replacement.
• Protection of the circulation pump against gas cavitation — extends pump service life.
• Silent system — radiators no longer produce gurgling from air bubbles.

Related Products

For comprehensive protection of the system against both air and dirt simultaneously — browse the Termojet separator catalogue, where 2-in-1 combined models are available. If a larger diameter is required — air separator DN32 TJ-CA.

FAQ

Why do I need an air separator if there is already a manual bleed valve on every radiator?
The manual bleed valve removes free (large) air — bubbles that have collected at the top of a radiator. Microbubbles (less than 1 mm) and dissolved gas are not vented by the valve: they circulate in the system, reduce heat transfer, accelerate corrosion, and wear out the pump. The air separator captures precisely these — and does so continuously, without manual intervention.

Where should the air separator be installed?
Immediately after the boiler (or after the mixing unit) on the supply pipe — at the hottest point in the system. At maximum temperature, gas solubility in the heat-transfer fluid is at its lowest, and microbubbles are released most actively — that is exactly where they are easiest to intercept.