HFT40003Z-01 High Temperature Opens One-Way Temperature Limit Valve
The Legom HFT40003Z-01 High Temperature Opens One-Way Temperature Limit Valve is a G1 thermostatic one-way valve that opens when water temperature rises above the preset threshold and closes when temperature falls below it — the functional opposite of the low temperature opening variants in the Legom HFT range. This high temperature opening behavior makes the HFT40003Z-01 suited to applications where flow through a specific circuit must be permitted only when the water reaches a defined elevated temperature, such as solar collector bypass circuits, thermal dump valves, and OEM water heater overheat protection systems.
Featuring an electroplated integrated water inlet connector and an electroplated handwheel on a 57-3 copper body, the HFT40003Z-01 combines the distinctive high temperature opening function with a premium metallic connector finish and compact integrated inlet design. Temperature adjustment range 20–60°C, control accuracy ±2°C, working pressure range 0.03–1 MPa, compatible with hot water inlet 30–99°C and cold water inlet 5–29°C.
Key Benefits
- Opens at high temperature — unique control behavior – The valve opens when water temperature rises above the preset threshold and closes when temperature falls below it. This is the functional opposite of the HFT33019Z-01/HFT33009Z-01 low temperature opening valves and enables flow gating based on high temperature detection — for applications where a circuit should only be active when water is hot enough
- Electroplated integrated water inlet connector – The inlet connector carries an electroplated metallic finish and is integrated into the valve body, combining premium appearance at the connection point with reduced external fitting count at the inlet side
- Electroplated handwheel – Metallic surface finish on the ABS handwheel provides a premium visual appearance suited to OEM water heater products and visible installation locations
- G1 connection (DN25) for mid-range flow – Higher flow capacity than domestic G3/4, suited to larger domestic and light commercial applications where the high temperature opening function is required at greater throughput
- ±2°C temperature control accuracy – Precise threshold detection for consistent open/close behavior at the defined temperature set point
- 20–60°C adjustment range – Wide set point range for flexibility across different high temperature threshold requirements
- No electricity required – Self-acting thermostatic operation powered entirely by sensed water temperature
- Wide pressure range 0.03–1 MPa – Covers gravity-fed through standard mains-pressure applications
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | HFT40003Z-01 |
| Valve Type | One-way, high temperature opening, fixed temperature |
| Body Material | 57-3 copper |
| Handwheel | ABS with electroplating |
| Inlet Connector | Electroplated integrated water inlet connector |
| Connection | G1 internal thread (DN25) |
| Temperature Adjustment Range | 20–60°C (standard); 35–55°C / 40–50°C / 30–60°C (preset options) |
| Temperature Control Accuracy | ± 2°C |
| Working Pressure Range | 0.03 MPa – 1 MPa |
| Ideal Working Pressure | 0.1 MPa – 0.5 MPa |
| Cold Water Temperature Range | 5°C – 29°C |
| Hot Water Temperature Range | 30°C – 99°C |
| Primary Use | Water heater (OEM thermostatic management, specialist control) |
HFT One-Way Temperature Limit Valve Family — Opening Behavior Comparison
| Model | Opens When | Closes When | Typical Use |
|---|---|---|---|
| HFT33019Z-01 | Temperature falls below threshold | Temperature rises above threshold | Recirculation, low temp detection |
| HFT33009Z-01 | Temperature falls below threshold | Temperature rises above threshold | Premium finish, recirculation |
| HFT40003Z-01 | Temperature rises above threshold | Temperature falls below threshold | High temp activation, bypass, dump |
Application & Use Cases
- Solar thermal collector bypass and dump valve applications – In solar thermal systems, the collector loop can reach very high temperatures during stagnation. A high temperature opening valve activates a bypass or dump circuit when collector temperature rises above the preset threshold, preventing overheating of the system and connected components
- OEM water heater overheat protection circuits – Integrated into water heater assemblies as part of the heater’s thermostatic management system, opening a relief or bypass circuit when storage or outlet temperature rises above the set threshold to prevent overheating
- Heat pump system high temperature activation – In heat pump installations where a specific secondary circuit or component should only activate when the primary circuit water reaches a defined elevated temperature, the HFT40003Z-01 provides automatic flow gating without electrical controls
- Thermal dump valve applications – Systems that require excess thermal energy to be diverted to a dump load (such as a radiator or heat store) when water temperature exceeds a preset threshold — the HFT40003Z-01 opens the dump circuit automatically at the defined temperature
- Industrial and commercial thermostatic control circuits – Applications requiring a self-acting high temperature gate valve at G1 flow capacity without electrical actuation
Installation Notes
- Confirm the valve’s control behavior before installation: this valve opens when temperature rises above the set point and closes when temperature falls below it — the opposite of the low temperature opening variants. Verify this is the correct function for your application
- Connect supply pipework to the electroplated integrated inlet connector and distribution to the outlet port using appropriate thread sealant on all G1 connections
- Position the valve so the thermostatic sensing element is in direct contact with the water whose temperature it must sense
- Install isolation valves upstream to enable servicing without system shutdown
- The valve performs optimally at 0.1–0.5 MPa
- For OEM integration dimensional drawings and detailed functional behavior documentation, contact the Legom technical team
Frequently Asked Questions
How does this valve differ from the low temperature opening variants in the HFT range?
The HFT33019Z-01 and HFT33009Z-01 are low temperature opening valves — they open when water temperature falls below the preset threshold and close when it rises above it. The HFT40003Z-01 is a high temperature opening valve — it opens when temperature rises above the threshold and closes when it falls below. This makes the HFT40003Z-01 appropriate for circuits that should only be active when water is hot enough, such as solar bypass, thermal dump, and overheat protection applications — the opposite use case from recirculation and low-temperature detection applications served by the low temperature opening variants.
What is an electroplated integrated water inlet connector?
The integrated water inlet connector is a connection fitting built directly into the valve body at the inlet side, reducing the external fitting count. The electroplating applies a metallic surface coating to this connector, providing both corrosion resistance and a premium metallic appearance at the connection point. This differs from a standard threaded port (no electroplating, no integration) and from a separately attached external connector (attached but not integrated into the body casting).
Can the opening temperature threshold be customized?
Yes. The 20–60°C adjustment range allows the high temperature opening threshold to be set across the full range. OEM orders can specify a factory-preset threshold to mechanically lock the set point at a defined temperature. Contact the Legom team with the specific threshold temperature required for your application.
OEM & ODM Customization
Legom supports full OEM and ODM services for the HFT40003Z-01 High Temperature Opens One-Way Temperature Limit Valve. Customization options include temperature threshold, electroplating specification on the connector, connection size, and body configuration. This model is suited to OEM thermostatic management integration — contact us with your complete requirements via WhatsApp or info@legomsmart.com.
Product information last reviewed by the Legom Technical Team. For the most current specifications, refer to the official datasheet or contact our sales team.
Custom OEM & ODM Solutions
Legom is a direct manufacturer offering end-to-end OEM and ODM services. With our in-house engineering and production capabilities, we work closely with distributors and system integrators to deliver fully customized solutions under strict NDA.
