Altecnic iStop Anti-Freeze Valve 28mm Compression | 108301

Description

The Altecnic iStop anti-freeze valve with 28mm compression ends (108301) protects heat pump pipework from freezing by draining the circuit medium when the temperature falls to an average of 3°C. This prevents ice forming in the circuit, avoiding damage to equipment, valves and pipework. It is offered as an alternative frost prevention measure to be installed with Vaillant aroTHERM plus heat pumps.

The valve opens at 3°C and closes again at 4°C (accuracy ±1°C), and is built from brass with stainless steel springs and EPDM seals. Both the vacuum breaker and the thermostatic cartridge can be replaced, with an automatic shut-off cock keeping the system pressurised during replacement.

3°C

Opening temperature

4°C

Closing temperature

10 bar

Max working pressure

28mm

Compression ends

0 to 65°C

Working temperature

-30 to 60°C

Ambient temperature

Correct installation is essential

Fit the valve vertically with the outlet facing down, outdoors and clear of heat sources. Install on both flow and return pipes, make no trap connections, and keep the system under pressure at all times. The valve must be free of insulation. Incorrect installation removes the frost protection.

Heat pump compatibility

Listed as an alternative frost prevention measure for Vaillant aroTHERM plus heat pumps. Always confirm the requirements in the heat pump manufacturer's installation instructions.

Drain and clearances

Leave at least 15cm clearance from the ground, keep at least 10cm between valves, route the drain to a suitable collection point, and protect the valve from rain, snow and direct sunlight.

Key features

Automatic frost protection

Drains the circuit when the medium reaches an average of 3°C and closes at 4°C.

Brass construction

Brass body with stainless steel springs and EPDM seals.

28mm compression ends

Compression connection to BS EN 1254 for direct 28mm pipework connection.

High flow

Kv of 55 m³/h through the straight path.

Serviceable cartridge

Replaceable vacuum breaker and thermostatic cartridge, with an automatic shut-off cock.

Low discharge rate

Discharge of 0.5 l/h at -5°C and 1 l/h at -20°C (at 3 bar).

Technical specification

General

Parameter

Specification

Brand

Altecnic (iStop)

Reference

108301

Connection size

28mm compression

Medium

Water

Connection standard

Compression to BS EN 1254

Performance

Parameter

Specification

Medium temperature, opening

3°C

Medium temperature, closing

4°C

Accuracy

±1°C

Maximum working pressure

10 bar

Working temperature range

0 to 65°C

Ambient temperature range

-30 to 60°C

Kv, straight path

55 m³/h

Discharge at 3 bar, -5°C

0.5 l/h

Discharge at 3 bar, -20°C

1 l/h

Materials

Parameter

Specification

Body

Brass, BS EN 12164 CW724R

Obturator

Brass, BS EN 12164 CW617N

Springs

Stainless steel, BS EN 10270-3 (AISI 302)

Seals

EPDM

Compression nut

Brass, BS EN 12165 CW617N

Olive

Brass, BS EN 12164 CW614N

Frequently asked questions

How does the valve work?

When the water in the pipe drops below 3°C the obturator opens and drains water off. It closes when the medium returns to 4°C.

Do I need one on both pipes?

Yes. Fit valves on both the flow and return pipes, otherwise water may be left in one pipe which could freeze.

Where should it be installed?

Outdoors, where the lowest temperatures are reached if the heat pump is not operating, vertically with the outlet facing down and away from heat sources.

Should the valve be insulated?

No. The valve must be free of insulation for the system to work properly, and protected from rain, snow and direct sunlight.

Can the cartridge be replaced?

Yes. The vacuum breaker and thermostatic cartridge can both be replaced, and an automatic shut-off cock keeps the system pressurised.

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