HFT33019Z-01 Fixed Temperature One-Way Low Temperature Opening Valve
The Legom HFT33019Z-01 Fixed Temperature One-Way Low Temperature Opening Valve is a thermostatic control valve that opens at a defined low temperature threshold and remains closed above it — the functional inverse of a standard thermostatic mixing valve. Rather than blending hot and cold water to a target temperature, the HFT33019Z-01 acts as a temperature-sensing gate: it opens when water temperature falls below the preset threshold and closes when temperature is at or above it, enabling automatic flow control based on low-temperature detection in water heater and hot water distribution systems.
Featuring external water inlet and outlet connectors and a natural color pickled 57-3 copper body, the HFT33019Z-01 is designed for OEM water heater integration and specialist thermostatic control applications where a fixed-temperature one-way opening function is required. The natural color pickling treatment leaves a clean, oxide-free natural brass surface on the connection areas without an applied plating layer. Temperature adjustment range 20–60°C, control accuracy ±2°C, G1/2 internal thread, working pressure range 0.03–1 MPa.
Key Benefits
- Fixed temperature, one-way low temperature opening function – Opens when water temperature falls below the preset threshold — a fundamentally different control function from standard TMVs that mix to a target temperature. This enables automatic flow activation based on low-temperature detection without manual intervention or electrical control
- External water inlet and outlet connectors – External connectors provide connection flexibility and simplify integration into water heater assemblies where the valve body needs to connect to external supply and distribution pipework at defined positions
- Natural color pickled copper body – Acid-cleaned natural brass surface on the valve body without an applied plating layer — providing a clean, oxide-free appearance preferred in OEM integrations where natural brass aesthetics are specified and where the absence of plating eliminates any risk of plating delamination
- G1/2 connection for compact installations – The smallest standard connection size, suited to point-of-use and compact water heater applications where the one-way low temperature opening function is required in the smallest available body
- ±2°C temperature control accuracy – Precise temperature threshold detection with ±2°C accuracy, ensuring consistent open/close behavior at the defined temperature set point
- 20–60°C adjustment range – Wide set point range covering domestic hot water temperature management from low-temperature thresholds through standard delivery temperatures
- No electricity required – Self-acting thermostatic operation powered by the sensed water temperature alone
- Wide pressure range 0.03–1 MPa – Covers gravity-fed through mains-pressure applications
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | HFT33019Z-01 |
| Valve Type | Fixed temperature, one-way, low temperature opening |
| Body Material | 57-3 copper, natural color pickling |
| Handwheel | ABS black (set) |
| Connection | G1/2 internal thread (DN15) |
| Connector Type | External water inlet and outlet connector |
| Body Surface | Natural color pickling (no plating) |
| 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 integration, specialist thermostatic control) |
HFT33019Z-01 vs Standard TMV — Functional Comparison
| Characteristic | HFT33019Z-01 | Standard HFT TMV |
|---|---|---|
| Function | One-way gate — opens at low temp | Blends hot and cold to target temp |
| Ports | One inlet, one outlet (one-way) | Hot inlet, cold inlet, mixed outlet |
| Opens when | Temperature falls below threshold | Always open — modulates mixing ratio |
| Closes when | Temperature rises above threshold | N/A — always open during use |
| Body finish | Natural color pickling | Nickel / chrome / surface plated |
| Connector | External connector | Standard threaded / union ports |
Application & Use Cases
- Water heater low-temperature detection and flow control – Applied in water heater systems where flow through a specific circuit must be permitted only when water temperature is below a defined threshold — for example, allowing cold water to enter a recirculation or mixing circuit when the hot water supply has cooled below the acceptable delivery temperature
- OEM water heater product integration – The external connector design, natural color pickled body, and fixed-temperature one-way function are purpose-built for integration into OEM water heater assemblies where a dedicated low-temperature gate valve is a component of the heater’s internal thermostatic management system
- Hot water recirculation system control – In H-type or similar hot water recirculation systems where a temperature-actuated one-way valve controls whether the recirculation circuit is open or closed based on the temperature of water at the sensing point
- Solar thermal system temperature management – In solar collector circuits where flow through a specific path must be gated based on a low-temperature threshold to prevent reverse thermosiphon or to initiate a specific circuit only when collector temperature falls below a set point
Installation Notes
- Connect supply pipework to the external inlet connector and distribution pipework to the external outlet connector — confirm the flow direction relative to the valve’s sensing and opening direction before installation
- The valve opens when sensed water temperature falls below the set point and closes when temperature rises above the threshold — verify this is the correct control behavior for your application before installing
- Use appropriate thread sealant on all G1/2 connection points
- 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, external connector interface specifications, and detailed functional behavior documentation, contact the Legom technical team directly
Frequently Asked Questions
How does the HFT33019Z-01 differ from a standard thermostatic mixing valve?
A standard thermostatic mixing valve has three ports — a hot inlet, a cold inlet, and a mixed outlet — and continuously blends hot and cold water to maintain a target mixed outlet temperature. The HFT33019Z-01 is a one-way valve with one inlet and one outlet that acts as a temperature-sensitive gate: it opens when the sensed water temperature falls below the preset threshold and closes when temperature rises above it. It does not blend water — it either allows flow or blocks it based on temperature. This makes it a fundamentally different product suited to temperature-based flow gating rather than temperature blending.
What is natural color pickling on the valve body?
Pickling is an acid-cleaning treatment that removes surface oxides and contaminants from the copper alloy body, leaving a clean, bright natural brass surface without any applied plating layer. Unlike nickel or chrome plating, no additional metal coating is applied — the surface is the natural color of the 57-3 copper alloy after acid cleaning. This provides a clean connection surface for thread sealant and a natural brass appearance preferred in specific OEM integration applications.
Can the opening temperature threshold be customized?
Yes. The temperature adjustment range of 20–60°C allows the opening threshold to be set across a wide range, with factory-preset options available for OEM orders that require a fixed, non-adjustable threshold. Contact the Legom team with your specific temperature threshold requirement and application details.
OEM & ODM Customization
Legom supports full OEM and ODM services for the HFT33019Z-01 Fixed Temperature One-Way Low Temperature Opening Valve. This model is purpose-built for OEM water heater integration — customization options include fixed temperature threshold, external connector specification, connection size, and body surface treatment. Contact us with your complete integration 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.
