Danfoss FHV-R - User Manual

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Overview

Function Description
Important Technical Specifications
Usage Features

The Danfoss FHV-R + FJVR Thermostat is a device designed for controlling heating systems, specifically those involving radiators and underfloor heating. It functions as a return temperature limiter, ensuring that the return temperature from the heating circuit does not exceed a set maximum. This is crucial for protecting sensitive components in the heating system, such as boilers or heat pumps, from excessively high return temperatures, and for optimizing the efficiency and comfort of the heating installation.

Function Description:

The FHV-R + FJVR Thermostat operates by sensing the return temperature of the heating medium. When this temperature reaches a predefined setpoint, the thermostat begins to close, restricting the flow of heating medium and thereby preventing the return temperature from rising further. Conversely, as the return temperature drops below the setpoint, the thermostat opens, allowing more hot water to circulate. This continuous modulation ensures a stable and controlled return temperature.

The FHV-R component is specifically designed for use in mixed systems with radiators and underfloor heating (UFH). In such configurations, the FHV-R valve is installed in the return line of the underfloor heating circuit. Its primary role is to limit the return temperature from the UFH, which is often a lower temperature circuit compared to radiators. This prevents the UFH circuit from sending excessively hot water back to the main system, which could be detrimental to certain heat sources or lead to inefficient operation.

The FJVR component, while not explicitly detailed in its separate function here, typically refers to a return temperature limiter valve. In the context of this combined system, it likely works in conjunction with the FHV-R or provides a similar return temperature limiting function for other parts of the heating system, or it might be an alternative or complementary valve type depending on the specific installation requirements. The overall objective is to manage the return temperature effectively across the entire heating installation.

The thermostat allows for precise temperature setting, enabling users to tailor the system's response to their specific comfort needs and the requirements of the heat source. This control helps in achieving optimal energy efficiency by preventing unnecessary overheating and ensuring that the heat source operates within its ideal temperature range.

Important Technical Specifications:

While specific numerical values for technical specifications like Kv-value, pressure rating, or maximum operating temperature are not provided in the given images, the device is clearly designed for hydronic heating systems. The temperature setting range is indicated as 10 to 50 °C, with markings for 10, 20, 30, 40, and 50 °C. This range is typical for return temperature limitation in underfloor heating applications, where lower temperatures are generally preferred to ensure comfort and prevent floor damage.

The installation diagrams show the thermostat integrated into pipework with a diameter of approximately 150 mm for the main pipe, suggesting it's suitable for standard residential or light commercial heating installations. The device is designed for easy integration into existing or new heating systems.

The "Frostschutzstellung" (frost protection setting) is a crucial safety feature, indicated by a snowflake symbol. This setting ensures that the system maintains a minimum temperature to prevent freezing of the heating medium in cold conditions, thereby protecting the pipes and components from damage.

Usage Features:

The Danfoss FHV-R + FJVR Thermostat offers several usage features that enhance its practicality and effectiveness:

Mixed System Compatibility: It is explicitly designed for "Fußbodentemperierung, Mischsystem" (underfloor heating, mixed system), meaning it can be used in installations that combine radiators and underfloor heating. This versatility makes it suitable for a wide range of modern heating setups.
Return Temperature Limitation: The core feature is its ability to limit the return temperature from the underfloor heating circuit, which is essential for protecting boilers, heat pumps, and other heat sources from high return temperatures.
Adjustable Temperature Setpoint: The thermostat allows users to set the desired return temperature within the 10-50 °C range, providing flexibility to optimize comfort and energy consumption.
Frost Protection: The integrated frost protection setting safeguards the system against freezing during periods of low ambient temperature or when the heating system is temporarily shut down.
Easy Installation: The installation diagrams illustrate a straightforward process, suggesting that the device is designed for relatively easy integration into the heating pipework. The visual steps show the connection of the valve body, the sensor, and the capillary tube, indicating a standard installation procedure for such thermostatic controls.
Clear Markings: The temperature scale and frost protection symbol are clearly marked on the thermostat head, making it easy for users or installers to understand and adjust the settings.
Maintenance Features:

While explicit maintenance instructions are not provided in the images, the design of such thermostatic valves generally implies low maintenance requirements.

Robust Construction: Danfoss products are typically known for their robust construction, ensuring long-term reliability and minimal need for frequent maintenance.
Self-Cleaning Action: The continuous movement of the valve stem during operation can help prevent the buildup of deposits, contributing to the valve's longevity.
Replaceable Components: In many thermostatic valves, the thermostatic element (head) can be replaced independently of the valve body, simplifying potential repairs and extending the life of the overall unit. This modularity reduces the cost and effort associated with maintenance.
Accessibility for Servicing: The installation diagrams suggest that the valve is installed in an accessible location within the pipework, which would facilitate any future servicing or inspection if required.

In summary, the Danfoss FHV-R + FJVR Thermostat is a critical component for managing return temperatures in hydronic heating systems, particularly those with underfloor heating. Its ability to limit return temperatures, combined with adjustable settings and frost protection, contributes to efficient, comfortable, and reliable heating operation while protecting the heat source. Its design for mixed systems and ease of installation make it a versatile choice for modern heating installations.