Danfoss Link™ & Connect Thermostats

1.1 Segment

This application guide covers the use of Danfoss Link™, Danfoss Link™ Connect Thermostat wireless heating controls and Danfoss Eco™ in 1 and 2 family houses and flats up to 300 m².

1.2 Danfoss Eco™ programmable radiator thermostat

Danfoss Eco™ is a stand-alone intelligent and programmable radiator thermostat* for residential use, where a central control system is not available. It is easy to install and is supplied with adapters for all thermostatic valves manufactured by Danfoss and most other radiator valve manufacturers.

1.3 Overview of units in a Danfoss Link™ system

The following units can be used in a Danfoss Link™ wireless system:

• Danfoss Link™ CC Central Controller: The unit from which the entire installation can be controlled. One Danfoss Link™ CC is always needed in a system. (Visual: A white, rectangular device with a screen displaying '21.5°'.)
• Danfoss Link™ Connect Thermostat: An electronic radiator thermostat* for residential use, which is controlled by a Danfoss Link™ CC. (Visual: A white, circular thermostat with a dial showing '21°'.)
• Danfoss Link™ HC Hydronic Controller: Allows control of hydronic floor heating with a large range of functions. (Visual: A white, rectangular unit with a circular dial and indicator lights.)
• Danfoss Link™ RS Room Sensor: Used for measuring and adjusting the room temperature. (Visual: A small, white, circular device with a dial showing '21°'.)
• Danfoss Link™ FT Floor Thermostat: Used for measuring and adjusting electrical floor heating. (Visual: A white, rectangular device with a circular dial and indicator lights.)
• Danfoss Link™ BR Boiler Relay: A unit for turning gas and oil boilers ON/OFF, depending on heating demand. (Visual: A white, rectangular unit with a dial and an ON/OFF switch.)
• Danfoss Link™ RU Repeater Unit: Used for extending the wireless transmission range between Danfoss Link™ CC and other units in a system. (Visual: A white, rectangular plug-in unit with an indicator light.)

* Danfoss recommends using Connect and Eco™ Thermostats together with Danfoss radiator valves with integrated pre-setting in order to achieve optimal performance. For choice of adaptor please use the Danfoss adaptor guide, which also includes adaptors for non Danfoss valves.

1.4 Number of units in a Danfoss Link™ system

When building a wireless Danfoss Link™ control system it is important to follow these rules:

1. The total number of units must not exceed 50 (1 Danfoss Link™ Central Controller + 49 units).
2. The number of each type of unit must not exceed:
   • Danfoss Link™ CC: 1 unit
   • Connect Thermostat: 30 units
   • Danfoss Link™ HC: 3 units
   • Danfoss Link™ RS: 30 units
   • Danfoss Link™ FT: 30 units
   • Danfoss Link™ BR: 1 unit
   • Danfoss Link™ RU: 3 units

1.5 Best practice

Mains powered units

Avoid disconnecting mains powered units in a Danfoss Link™ system. In the event this happens the system will eventually re-establish the network, when repeater unit is reconnected to the mains power. (Visual: A diagram showing a mains power plug and socket, with a red 'X' over the plug, indicating that mains powered units should not be disconnected. A separate image shows a Danfoss Link™ RU unit plugged into a wall socket, labeled '230 V'.)

Danfoss Link™ RU Repeater units

It is always recommended to use Danfoss Link™ RU, when a repeater is needed to extend the radio communication range. Several mains powered units (such as relays) also act as repeaters, but with limited capability to improve the communication range compared to Danfoss Link™ RU. Danfoss Link™ RU repeaters should always be registered as the first 230 V units in the system.

2.1 Heat supply

If the heating system has been optimized for constant set temperature around the clock, you may need to adjust the settings when working with setback periods. When changing the temperature from a low economy setting to a comfort temperature, the system must be able to supply enough heat to raise the room temperature at least 1 °C per hour to perform well. Compared to a steady temperature the heating system must typically be able to supply 25% more heat, but only for a short period of time during heat up.

(Visual: A graph illustrates heating system performance with phases labeled 'ECONOMY', 'COMFORT', and 'BOOST', showing energy output relative to demand.)

How to achieve 25% extra capacity in a system that should run boost:

Note: Maximum acceptable presetting, water temperature and pump differential pressure settings are different from system to system and depend on the application.

For radiator valves with pre-setting, balance the system to allow for enough flow.

The supply line temperature at the radiator valves should be above 40 °C to ensure optimal control. (Visual: A thermometer icon showing 'min. 40 °C' next to a radiator.)

Make sure that the supply water temperature and flow is adequate to provide enough energy. Increase the temperature or the pump level, if necessary.

2.2 Functions

Connect Thermostats have a built-in function, which automatically shut off the heat while the room is ventilated. When the thermostat detects a drop in room temperature, it closes the valve.

To prevent excessive cooling of the room, the thermostat will automatically open the valve again after 30 minutes, meaning that during longer periods of ventilation you must manually set the temperature down.

To prevent multiple detections of ventilation, e.g. caused by opening a door, leading to instability, the thermostat will not detect a new ventilation session in a period of 45 minutes from the previous occurrence.

Be aware that a large window sill might prevent the Connect Thermostat from detecting cold air from an open window, and thereby not activate the automatic Open-window function. (Visual: An illustration of a radiator with a thermostat, showing heat being shut off when a window is open. Another illustration shows a window with a large sill potentially obstructing the thermostat's view of an open window.)

If the radiator is under or oversized in relation to the room, the settings should be changed accordingly. (Visual: An illustration showing a radiator and a thermostat, with wavy lines indicating potential temperature discrepancies due to radiator size relative to the room.)

Connect Thermostat: to change the settings, please refer to the Connect Thermostat installation and user guide.

2.3 Rooms

The adaptive learning function (Forecast) ensures that the comfort temperature is reached at set time. The warm up time is continuously adjusted according to seasonal temperature changes.

• Adaptive learning ensures the wanted temperature at the wanted time (here 20 °C at 07:00).
• Adaptive learning uses data from the previous 7 days to be able to reach the correct temperature at the right time.
• Adaptive learning is sensitive to large, rapid temperature changes.

(Visuals: Diagrams illustrate seasonal temperature changes: 'Winter: Long warm up time.' with a clock showing a long duration and a snowman icon, and 'Spring/fall: Short warm up time.' with a clock showing a shorter duration and a sun icon.)

Covering the radiator - e.g. with furniture, curtains or a radiator cover - might cause heat to be accumulated around the thermostat.

Room Coverage Advice:

• Light curtain/furniture: Connect Thermostat: can be used, but function is improved by using a RS room sensor. Danfoss Eco™: can be used, but it might be necessary to raise the set temperature. (Visual: An illustration of a radiator partially covered by a light curtain or furniture, with a thermostat on it.)
• Medium curtain/furniture: Connect Thermostat: use with Danfoss Link™ RS room sensor. Danfoss Eco™: can be used, but it might be necessary to raise the set temperature.
• Radiator cover: Connect Thermostat: use with Danfoss Link™ RS room sensor. Danfoss Eco™: not recommended in this situation. (Visual: An illustration of a radiator enclosed in a decorative cover.)

If two radiators are placed within 40 cm of each other, the heat emission from one radiator can affect the thermostat on the other radiator.

• Connect Thermostat: use with Danfoss Link™ RS room sensor.
• Danfoss Eco™: balance the two radiators by adjusting the set temperature on the affected radiator. (Visual: An illustration showing two radiators placed close together.)

3.1 Heating System with Boiler

Description

A boiler with build-in or external domestic hot water tank can provide instant heat for the heating system, as well as for the domestic hot water. The system can be operated with or without a Danfoss Link™ BR (Boiler Relay). (Visual: An illustration of a house with a boiler and radiators, representing a heating system with a boiler.)

Minimum requirements

• minimum 40 °C supply temperature at the valve.
• sufficient heating capacity to increase the room temperature with 1 °C per hour.
• only radiator valves approved for Danfoss adapters.

Note! Bypass valve is recommended.

Recommendations

Central room temperature with night setback

If a central room temperature controller is used in combination with Connect Thermostats, it must only be as temperature limiter. (Visual: A diagram showing a central room temperature controller connected to a Connect Thermostat, illustrating set temperature ranges: Max. temp., Comfort temp., Setback temp., Min. temp.)

Boiler turned off at night

If the boiler is turned off or has reduced temperature during the night, then make sure that it is active when the Connect Thermostat is programmed to warm. In a system with Danfoss Link™ CC and Connect Thermostat, this can be controlled automatically by adding a boiler relay.

(Visuals: Two circular timer diagrams showing 'Boiler OFF' and 'Boiler ON' periods for a 24-hour cycle. One is labeled 'With Forecast' and the other 'Without Forecast'.)

Weather compensation

If the boiler's heating curve is set to have the radiator thermostats on comfort temperature constantly, the curve must be increased in order to be able to raise the room temperature after a setback period.

• If the setback periods are long, further increase might be necessary.
• If the economy periods are short, less increase can be sufficient.

(Visual: A graph showing 'Supply Water Temperature (°C)' on the Y-axis and 'Outdoor Air Temperature (°C)' on the X-axis. Two lines illustrate different heating curves, indicating how supply water temperature should adjust with outdoor temperature.)

Boiler relay

Set Danfoss Link™ BR boiler relay to automatic ON/OFF in the Danfoss Link™ set-up menu.

3.2 Heating System with Central Boiler

Description

A large gas, oil or pallet boiler which provides hot water to several households. (Visual: An illustration of a multi-story building with a central boiler, representing a heating system with a central boiler.)

Minimum requirements

• min. 40 °C supply temperature at the valve.
• sufficient heating capacity to increase the room temperature with 1 °C per hour.
• only radiator valves approved for Danfoss adapters.

Recommendations

Boiler turned off at night

If the boiler is turned off or has reduced temperature during the night, then make sure that it is active when the Connect Thermostat is programmed to warm. In a system with Danfoss Link™ CC and Connect Thermostat, this can be controlled automatically by adding a boiler relay.

(Visuals: Two circular timer diagrams showing 'Boiler OFF' and 'Boiler ON' periods for a 24-hour cycle. One is labeled 'With Forecast' and the other 'Without Forecast'.)

Weather compensation

If the boiler's heating curve is set to have the radiator thermostats on comfort temperature constantly, the curve must be increased in order to be able to raise the room temperature after a setback period.

• If the setback periods are long, further increase might be necessary.
• If the economy periods are short, less increase can be sufficient.

(Visual: A graph showing 'Supply Water Temperature (°C)' on the Y-axis and 'Outdoor Air Temperature (°C)' on the X-axis. Two lines illustrate different heating curves, indicating how supply water temperature should adjust with outdoor temperature.)

3.3 District Heating

Description

District heating is generated in a centralized location and distributed to residential and commercial use. (Visual: An illustration of a centralized heating plant connected via pipes to several buildings, representing a district heating system.)

Minimum requirements

• min. 40 °C supply temperature at the valve.
• sufficient heating capacity to increase the room temperature with 1 °C per hour.
• only radiator valves approved for Danfoss adapters.

Recommendations

Weather compensation / ECL

If the boiler's heating curve is set to have the radiator thermostats on comfort temperature constantly, the curve must be increased in order to be able to raise the room temperature after a setback period.

• If the setback periods are long, further increase might be necessary.
• If the economy periods are short, less increase can be sufficient.

(Visual: A graph showing 'Supply Water Temperature (°C)' on the Y-axis and 'Outdoor Air Temperature (°C)' on the X-axis. Two lines illustrate different heating curves, indicating how supply water temperature should adjust with outdoor temperature.)

3.4 Heat Pump

Description

A heat pump is generating heating by transferring heat from a relatively low-temperature reservoir, such as air or ground, to one at a higher temperature. (Visual: An illustration of a house with a heat pump unit and radiators, representing a heat pump heating system.)

Minimum requirements

• min. 40 °C supply temperature at the valve.
• sufficient heating capacity to increase the room temperature with 1 °C per hour.
• only radiator valves approved for Danfoss adapters.

Recommendations

Weather compensation

If the heat pump's heating curve is set to have the radiator thermostats on comfort temperature constantly, the curve must be increased in order to be able to raise the room temperature after a setback period.

• If the setback periods are long, further increase might be necessary.
• If the economy periods are short, less increase can be sufficient.

(Visual: A graph showing 'Supply Water Temperature (°C)' on the Y-axis and 'Outdoor Air Temperature (°C)' on the X-axis. Two lines illustrate different heating curves, indicating how supply water temperature should adjust with outdoor temperature.)

If the system is installed during a period with outside temperature > 10° C, the opening point will not be found until the temperature drops below 7-8° C. This can be solved by manually setting the heating curve higher during the run-in period (approx. 1 week).