Antifreeze valve Termojet DN32 (1 1/4" M)

The Termojet DN32 antifreeze valve (thread 1 1/4"M) is a brass thermosensitive device for freeze protection in larger-diameter pipelines. When the coolant temperature drops to the critical threshold of ≈+3°C, the valve opens automatically and drains a portion of the fluid from the pipeline, preventing the destructive pressure caused by ice expansion. Once normal temperature is restored, it closes by itself without any operator intervention.

Technical Specifications

Operating Principle

The thermosensitive element in the valve body continuously responds to the coolant temperature in the pipeline. When the temperature drops to ≈+3°C — before the water begins to crystallize — the thermoelement expands and opens the plug. A portion of the coolant exits through the drain nozzle into the drainage system, the pressure in the system drops and the risk of pipe or radiator bursting is eliminated.

The enlarged DN32 diameter (1 1/4") provides higher flow capacity compared to DN25 — which is critical for main pipelines where the coolant volume is greater and an adequate cross-section is required for effective pressure relief. For smaller-diameter pipelines — Antifreeze valve DN25.

Applications

• Main pipelines DN32 and above. Boiler rooms of private cottages, small commercial and industrial buildings — where the main distribution pipeline is 32 mm in diameter or larger.
• High-capacity heat pump systems. External circuits and pipework of heat pumps rated 10 kW and above, where pipelines are made in DN32. In the event of an emergency shutdown, the valve protects the entire external circuit from freezing.
• Branched heating systems in multi-storey cottages. The main riser or horizontal main passing through unheated zones (basement, technical floor, extension) — the most vulnerable sections when heating is switched off.
• Industrial and commercial facilities with seasonal use. Warehouses, agro-industrial premises, heated garage complexes — where the freezing risk in winter during downtime is highest.
• Backup protection line in case of boiler failure. Even if the main equipment has failed and the owner is unavailable — the valve will activate autonomously and protect the pipelines without any communication or power supply.

Advantages of Termojet DN32

• Enlarged DN32 flow cross-section — effective pressure relief in large-diameter main pipelines.
• Full autonomy — no power supply, sensors or controllers, no maintenance.
• Activation at ≈+3°C — with a guaranteed margin before the onset of water crystallization.
• Self-restoring after warm-up — the valve is ready for operation again without replacement or resetting.
• Brass body — corrosion-resistant, compatible with all common heat transfer fluids, maximum pressure 10 bar.

Antifreeze Valve and Heat Pump

For heat pumps with an output from 10 kW, the pipework is made with DN32 and larger pipelines. In the event of an emergency heat pump shutdown — due to power supply failure, automation error, or technical fault — the external pipelines can freeze within a few hours in severe frost. The DN32 antifreeze valve activates autonomously and releases pressure before the ice has time to burst the pipe. Learn about comprehensive heat pump system design on the Termojet heat pumps website.

Frequently Asked Questions

What is the difference between DN25 and DN32 — and how do I choose?
The difference lies in the flow cross-section and, consequently, in the pressure relief capacity. DN25 is suitable for G1"/DN25 pipelines in standard-size private homes. DN32 is required where the main pipeline is 32 mm in diameter or larger — otherwise a smaller-diameter valve will not provide sufficient pressure relief and will not protect the system effectively. If in doubt, refer to the pipe diameter at the valve installation point.

Is maintenance required after activation?
The valve closes by itself after warm-up and is ready for re-activation. However, after each activation it is recommended to: check the coolant level and pressure in the system and top up if necessary; make sure the valve has not remained in the open position. More accessories for a reliable heating system are available in the Termojet additional equipment catalogue.