28mm Off-Side ASHP Antifreeze Valve
The 28mm Off-Side ASHP Antifreeze Valve ZL-7207-28MM provides automatic frost protection for suitable water-based air source heat pump systems. Its alternative off-side configuration suits installations where pipe orientation or discharge position makes a standard valve arrangement less convenient. The valve opens at approximately 3°C and closes again at approximately 4°C, without requiring electrical power.
28mm Off-Side Heat Pump Antifreeze Valve
The ZL-7207-28MM performs the same essential frost-protection function as a standard heat pump antifreeze valve.
However, its off-side configuration provides an alternative physical arrangement.
Therefore, installers can choose the version that best suits the available pipework, installation space and discharge position.
Exact Product Code ZL-7207-28MM
The manufacturer product code is:
ZL-7207-28MM
This identifies the dedicated 28mm off-side version within the Bastion antifreeze-valve range.
Using the exact product code also makes future replacement and servicing easier.
Automatic Frost Protection for ASHP Systems
Monobloc air source heat pumps often contain water-filled pipework outside the building.
During freezing weather, that water can become vulnerable if circulation stops.
The antifreeze valve responds automatically as water temperature approaches freezing.
Therefore, it provides additional protection for exposed heat pump pipework and hydraulic components.
Opens Automatically at Approximately 3°C
The temperature-sensitive mechanism monitors the water passing through the valve.
When the water reaches approximately 3°C, the valve opens and allows cold water to discharge.
This helps prevent the circuit water from reaching freezing point.
Closes Again at Approximately 4°C
Once warmer system water reaches the valve and its temperature rises to approximately 4°C, the mechanism closes again.
Therefore, the valve can automatically return to its normal operating position.
The published temperature sensitivity is ±1°C.
What Does Off-Side Mean?
The off-side version uses a different valve and discharge arrangement from the standard 28mm model.
Both valves perform the same fundamental frost-protection function.
However, the off-side configuration may better suit installations where surrounding pipework or available space makes the standard valve awkward to position.
Off-Side vs Standard 28mm Antifreeze Valve
Kudos Trading supplies both configurations.
Choose the standard 28mm ASHP Antifreeze Valve where its conventional arrangement works with the pipe layout.
Choose this 28mm off-side version where the alternative position provides a better installation or discharge arrangement.
The hydraulic system and heat pump manufacturer’s requirements should determine the final choice.
No Electricity Required
The antifreeze valve operates mechanically.
Therefore, it does not require:
- Mains electricity
- Batteries
- Wi-Fi
- External temperature sensors
- Heating controls
- Control cables
This remains particularly useful during power failures.
Helps Protect During Power Cuts
A winter power cut can stop both the heat pump and circulation pump.
Consequently, water can remain stationary inside exposed external pipework.
Because this antifreeze valve operates mechanically, it can continue responding to falling water temperature without electrical power.
Designed for Monobloc Heat Pumps
Monobloc heat pumps contain part of the water circuit within the outdoor unit.
Therefore, external flow and return pipework can remain exposed to winter conditions.
A correctly specified mechanical antifreeze valve can provide additional frost protection where approved by the heat pump manufacturer.
28mm Pipe Connection
This model provides a 28mm connection for compatible heat pump pipework.
Therefore, it integrates easily into many UK ASHP installations using 28mm primary pipework.
Always check the adjoining pipe, valve and fitting dimensions before ordering.
10 Bar Maximum Static Pressure
The Bastion antifreeze-valve range has a published maximum static inlet pressure of 10 bar.
This covers the working pressures found in many domestic and light-commercial heat pump installations.
However, always check the complete system design before installation.
0°C to 65°C Working Temperature
The published system-water operating range is:
0°C to 65°C
The published ambient range is:
-30°C to 60°C.
Therefore, the valve is designed for outdoor heating applications where very low ambient temperatures can occur.
High-Flow Design
The published Kv value is 55m³/h for the Bastion antifreeze-valve range.
As a result, the valve provides a high-flow path suitable for compatible heat pump hydraulic systems.
Always size the complete system according to the heat pump manufacturer’s flow requirements.
Suitable for Water Systems
The manufacturer specifies the antifreeze-valve range for water.
If the heating circuit contains glycol, check the heat pump manufacturer’s requirements before installing mechanical antifreeze valves.
Different ASHP systems use different frost-protection strategies.
Install on Flow and Return Where Required
Some heat pump installations require antifreeze protection on both the exposed flow and return pipework.
This allows cold water to leave vulnerable external sections of the system.
However, the exact arrangement depends on the heat pump.
Always follow the manufacturer’s installation instructions.
Correct Positioning Matters
Install the valve where it can accurately sense the temperature of exposed system water.
In addition, make sure the discharge outlet remains free to drain.
Avoid locations where:
- The valve sits next to an artificial heat source
- Water cannot discharge freely
- Pipework creates a trapped section
- The discharge could create a hazard
- The valve becomes inaccessible for servicing
Keep the Discharge Outlet Clear
The antifreeze valve protects the system by releasing water.
Therefore, never cap or obstruct its discharge route.
Also consider where the discharged water will travel.
During very cold weather, discharged water can freeze on the ground and create an ice hazard.
Antifreeze Valve or Glycol?
Heat pump manufacturers use different frost-protection strategies.
Some systems rely on mechanical antifreeze valves.
Others specify glycol within the primary circuit.
The correct approach depends on:
- Heat pump manufacturer
- Hydraulic design
- Outdoor pipework
- Installation location
- Water-treatment requirements
- Manufacturer warranty conditions
Therefore, always follow the heat pump manufacturer’s instructions.
Ideal for Replacement and Service Work
The ZL-7207-28MM also provides a useful replacement component for existing heat pump installations.
Typical reasons for replacement include:
- Existing valve leakage
- Physical damage
- System alterations
- Pipework upgrades
- Frost damage
- Heat pump replacement
- Servicing
- Installation redesign
Using the exact product code makes identifying the correct off-side version easier.
Part of the Kudos ASHP Antifreeze Valve Range
Kudos Trading is expanding its antifreeze-valve range to provide installers with more connection and installation options.
The range includes:
- 28mm standard
- 28mm off-side
- 1″ male
- 1¼″ male
- 1½″ male
- 1″ male x female swivel
- 1¼″ male x female swivel
The Bastion product range confirms the standard and off-side 28mm versions alongside the threaded options.
Key Features
- 28mm connection
- Off-side configuration
- Product code ZL-7207-28MM
- Automatic frost protection
- Opens at approximately 3°C
- Closes at approximately 4°C
- ±1°C temperature sensitivity
- No electrical power required
- No batteries required
- 10 bar maximum static inlet pressure
- 0°C to 65°C water-temperature range
- -30°C to 60°C ambient range
- Kv 55m³/h
- Suitable for water
- Ideal for compatible monobloc heat pumps
- Useful for ASHP replacement work
- Alternative to the standard 28mm configuration
Technical Specifications
| Specification | Details |
|---|---|
| Brand | Kudos Trading |
| Product | Off-Side ASHP Antifreeze Valve |
| Product Code | ZL-7207-28MM |
| Connection Size | 28mm |
| Configuration | Off-Side |
| Medium | Water |
| Maximum Static Inlet Pressure | 10 Bar |
| Working Temperature Range | 0°C to 65°C |
| Ambient Temperature Range | -30°C to 60°C |
| Opening Temperature | Approx. 3°C |
| Closing Temperature | Approx. 4°C |
| Temperature Sensitivity | ±1°C |
| Kv Value | 55m³/h |
| Electrical Supply | Not Required |
| Application | Air Source Heat Pump / Water-Based Heating |
Published Bastion product information identifies ZL-7207-28MM as the 28mm off-side model and gives the operating specifications above.
Why Choose the 28mm Off-Side Antifreeze Valve?
Key benefits include:
- Alternative installation configuration
- Designed for 28mm heat pump pipework
- Automatic frost protection
- Mechanical operation
- Works without electricity
- Useful during power cuts
- Opens before water reaches freezing point
- High-flow design
- Suitable for compatible ASHP installations
- Ideal for new installations
- Useful for retrofit projects
- Suitable for replacement work
- Alternative to the standard 28mm valve
Why Buy From Kudos Trading?
Kudos Trading supplies professional air source heat pump, heating and plumbing components throughout the UK.
Our growing Air Source Heat Pump Parts & Spares range includes antifreeze valves, flexible hoses, flow-balancing valves, fill and flush valves, magnetic filters and air separators.
Therefore, installers can source more of the components required for ASHP installation, servicing and repair from one supplier.
We have supplied underfloor heating products to the UK since 2001.
Frequently Asked Questions
What Is a 28mm Off-Side Antifreeze Valve?
It is a mechanical frost-protection valve with an alternative physical configuration to the standard 28mm version.
The off-side design can better suit certain pipework and discharge layouts.
What Is the Product Code?
The exact product code is ZL-7207-28MM.
What Does Off-Side Mean?
Off-side describes the alternative arrangement of the valve and discharge assembly.
It provides installers with another option where the standard configuration does not suit the available space or pipework layout.
Is It Different from the Standard 28mm Antifreeze Valve?
The main difference is the physical configuration.
Both provide automatic frost protection, but the off-side layout may suit different installation arrangements.
At What Temperature Does It Open?
The valve opens at approximately 3°C.
At What Temperature Does It Close?
The valve closes again at approximately 4°C.
Does It Need Electricity?
No.
The valve operates mechanically and does not require an electrical supply.
Will It Work During a Power Cut?
Yes.
Because the valve does not need electricity, it can continue reacting to low water temperatures during a power failure.
Is It Suitable for a Monobloc Heat Pump?
Yes, where the heat pump manufacturer permits mechanical antifreeze valves as part of the frost-protection strategy.
Does It Fit 28mm Pipework?
Yes.
This model is the 28mm off-side version.
What Is the Maximum Working Pressure?
The published maximum static inlet pressure is 10 bar.
What Is the Working Temperature Range?
The published system-water range is 0°C to 65°C.
The ambient range is -30°C to 60°C.
What Is the Kv Value?
The published Kv value is 55m³/h.
Should I Choose Standard or Off-Side?
Choose whichever configuration best suits the pipework layout and safe discharge arrangement.
Where the standard configuration works, use the 28mm ASHP Antifreeze Valve.
Where the alternative arrangement is more suitable, use this off-side model.
Related Products
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- 28mm Fill & Flush Valve
- Heat Pump Flow Balancing Valve with Fill & Flush
- 1″ Female Swivel x 28mm Extended Lever Ball Valve Pair
- 28mm Magnetic Central Heating Filter
- Microbubble Deaerator 28mm
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- Air Source Heat Pump Parts & Spares
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