28mm ASHP Antifreeze Valve | Heat Pump Frost Protection | Kudos Trading

28mm ASHP Antifreeze Valve

Automatic Heat Pump Frost Protection

Air source heat pumps often contain water-filled pipework outside the property.

During very cold weather, this water can become vulnerable to freezing. The risk becomes greater if circulation stops during a power cut or system fault.

The 28mm antifreeze valve responds automatically to falling water temperature.

When the water reaches around 3°C, the valve opens and allows water to discharge. As a result, it helps prevent ice forming within the exposed circuit.

Once the water temperature rises to around 4°C, the valve closes again automatically.

Designed for Air Source Heat Pumps

This valve has been designed for water-based heating systems that need protection against freezing.

It is particularly useful on monobloc air source heat pump installations. These systems often have water circulating between the outdoor unit and the property.

Therefore, exposed flow and return pipework needs suitable frost protection.

The valve works mechanically. Consequently, it does not need an electrical connection to operate.

28mm Compression Connections

This version uses 28mm compression connections.

Therefore, it fits directly into compatible 28mm copper heating pipework.

The compression arrangement also makes replacement straightforward when servicing an existing installation.

Always check the existing pipe size before ordering.

Opens at 3°C

The valve monitors the temperature of the water inside the heating circuit.

When the water temperature falls to approximately 3°C, the antifreeze mechanism opens.

This allows some system water to discharge before ice can form.

The valve then closes at approximately 4°C as the water temperature increases.

Protection During Power Cuts

A power cut can stop circulation through an air source heat pump.

If this happens during freezing weather, water inside exposed pipework can cool rapidly.

The antifreeze valve does not depend on the heat pump controller. Therefore, it can continue to provide mechanical frost protection when electrical power is unavailable.

This makes it a valuable safeguard for compatible water-based ASHP systems.

Helps Prevent Expensive Freeze Damage

Water expands when it freezes.

Consequently, frozen water can damage:

• Heat pump heat exchangers
• External pipework
• Valves
• Fittings
• Pumps
• Connections
• Other exposed hydraulic components

A correctly installed antifreeze valve helps reduce this risk.

Ideal for Water-Based Heat Pump Systems

This valve is designed for water-based systems.

Typical applications include:

• Air source heat pumps
• Monobloc heat pumps
• 28mm ASHP pipework
• Heat pump flow pipework
• Heat pump return pipework
• Renewable heating systems
• Heat pump replacement projects
• New ASHP installations
• Heat pump upgrades
• Heating system servicing

If the system uses glycol or another heat transfer fluid, follow the heat pump manufacturer’s frost-protection requirements.

Technical Specifications

Technical data follows the published specification for the ZL-7201-28mm valve.

Why Install Antifreeze Valves on Flow and Return?

A monobloc heat pump normally has both flow and return water pipework outside the building.

Therefore, both pipes can become vulnerable during freezing conditions.

Installing protection on both sides can help water drain safely from the exposed circuit.

Always follow the heat pump manufacturer’s installation requirements when deciding the number and position of antifreeze valves.

Where Should the Antifreeze Valve Be Installed?

Correct positioning is important.

Install the valve where it can detect cold system water and discharge freely.

The discharge outlet must remain clear. In addition, the surrounding pipework must not create a trap that prevents drainage.

Always follow the supplied installation instructions and the heat pump manufacturer’s hydraulic design.

Antifreeze Valve or Glycol?

Heat pump systems can use different frost-protection strategies.

Some installations use glycol-based heat transfer fluid. Others use water together with mechanical antifreeze valves.

Therefore, do not assume every system needs both.

Check the heat pump manufacturer’s guidance before selecting the frost-protection method.

Replacement 28mm Heat Pump Antifreeze Valve

Antifreeze valves may eventually require replacement during the life of a heat pump system.

Possible reasons include:

• Leakage
• Failed temperature cartridge
• Scale or debris
• Physical damage
• System alteration
• Heat pump replacement
• Pipework upgrade
• Routine refurbishment

This 28mm version provides a direct option for systems that use compatible 28mm connections and operating conditions.

Key Features

• Designed for air source heat pumps
• 28mm compression connections
• Automatic frost protection
• Opens at approximately 3°C
• Closes at approximately 4°C
• No electrical connection required
• Brass construction
• EPDM seals
• 10 bar maximum working pressure
• Suitable for water-based systems
• Suitable for ASHP flow and return pipework
• Ideal for new installations or replacement
• Helps prevent costly freeze damage

Why Buy From Kudos Trading?

Kudos Trading supplies professional heating, plumbing and renewable heating components throughout the UK.

We stock this 28mm ASHP antifreeze valve alongside a growing range of heat pump service and replacement parts.

In addition, our Nottinghamshire team can help with sizing and product questions before you order.

We have supplied underfloor heating products to the UK for over 26 years.

Frequently Asked Questions

What Does an ASHP Antifreeze Valve Do?

It helps prevent water from freezing inside exposed heat pump pipework.

The valve automatically releases water when the circuit reaches its operating temperature.

At What Temperature Does the Valve Open?

The valve opens at approximately 3°C.

It then closes again when the water temperature rises to approximately 4°C.

Does the Antifreeze Valve Need Electricity?

No.

The valve operates mechanically according to water temperature. Therefore, it can continue working during a power failure.

What Pipe Size Does This Valve Fit?

This model uses 28mm compression connections.

Always confirm the existing pipe size before ordering.

Should I Fit Two Antifreeze Valves?

Many heat pump installations use frost protection on both the flow and return pipework.

However, always follow the heat pump manufacturer’s installation requirements.

Is This Suitable for a Monobloc Heat Pump?

Yes, it can suit compatible water-based monobloc ASHP systems.

Check the heat pump manufacturer’s hydraulic specification before installation.

Can I Use This Instead of Glycol?

Some water-based heat pump systems use antifreeze valves instead of glycol.

However, the correct frost-protection strategy depends on the heat pump manufacturer and system design.

Is This the Same as the Fernox TF1 28mm Valve?

No.

This is the Kudos Trading ZL-7201-28MM antifreeze valve.

The Fernox TF1 28mm Antifreeze Valve is a separate branded product.

What Is the Maximum Working Pressure?

The maximum working pressure is 10 bar.

What Is the Operating Temperature Range?

The system-water working range is 0°C to 65°C.

The published ambient range is -30°C to 60°C.

Related Products

• 28mm Antifreeze Valve – Off Side
• Fernox TF1 28mm Antifreeze Valve
• 28mm Magnetic Y Strainer
• 28mm Lever Ball Valve Full Bore
• Lever Ball Valves
• Fernox F1 Protector Central Heating Inhibitor 500ml
• Fernox Water Treatment

Next Working Day Delivery

Yes, we hold all our products in stock at our 7,000 sq ft Nottingham warehouse and at our 3,000 sq ft warehouse in Market Harborough.

We use DPD for tracked next-working-day delivery.

Collection Available

You can always collect from our Nottingham location and help yourself to a free tea or coffee.

ystem and safeguarding the operation of the system.