RT51 - Thermostat DANFOSS - Free user manual and instructions

Product type	Room thermostat
Brand	Danfoss
Model	RT51
Power supply	2 AA alkaline batteries (1.5 V)
Dimensions (W x H x D)	110 x 88 x 28 mm
Temperature range	5 to 30 °C
Temperature accuracy	±1 °C
Clock accuracy	1 minute (RT52 model)
Contact type	1 x SPDT, type 1B
Contact rating	3(1) A, 10-230 Vac
Manufacturing standards	EN60730-2-9
Rated impulse voltage	2.5 kV
Ball pressure test	75 °C
Pollution degree	2
Operating modes	On/Off and chrono-proportional
Temperature settings	Day and Night (reduced)
Programming	Manual (RT51); with timer (RT52)
Battery replacement	Quality alkaline batteries, 15-day delay after warning
Installation	By a qualified electrician
Wireless versions (RF)	Available (RT51-RF, RT52-RF) with RX receiver, range up to 30 m

Frequently Asked Questions - RT51 DANFOSS

How to install the RT51 thermostat?

The thermostat must be installed by a qualified electrician. Remove the wall plate, respect recommended spacings (140 mm to the right, 15 mm to the left, 30 mm above, 100 mm below). Ensure the device is in ON/OFF or chrono-proportional mode before mounting. Do not connect unnecessary neutral and earth cables.

How to replace the batteries of the RT51?

When the battery icon flashes, replace the used batteries with two new AA alkaline batteries within one minute to preserve the settings. You have 15 days after the warning before the device turns off. Always use quality alkaline batteries.

How to set day and night temperature?

Press the ▲ or ▼ buttons to set the day temperature in DAY mode (d). To switch to NIGHT mode (n), press ▲ and ▼ simultaneously, then use ▲ or ▼ to set the night temperature (between 5 and 30 °C or Off). Press simultaneously again to toggle between modes.

What to do if the screen remains blank?

If the screen is blank during normal operation, the batteries are discharged. Replace the batteries with new alkaline batteries, reset the device by removing the batteries for 2 minutes, then reprogram the time and temperatures.

How to set the clock on the RT52?

On the RT52 model, press PROG once, then use ▲ or ▼ to set the time. Press PROG again to set the return time to day temperature. A final press of PROG returns to operation mode (RUN).

What is the difference between ON/OFF and chrono-proportional modes?

In ON/OFF mode, the boiler turns on when the temperature drops below the setpoint and turns off when it exceeds. In chrono-proportional mode, the thermostat triggers the boiler at intervals to maintain a constant temperature with better energy savings and stable comfort.

How to pair the wireless thermostat with the RX receiver?

For RF models, reset the thermostat (remove batteries for 2 min). Press the V and + buttons for 3 seconds to emit a continuous signal. On the RX receiver, press PROG and CH1 (or CH2, CH3 depending on the zone) until the indicator flashes. Finish by setting a temperature on the thermostat.

What are the necessary spacings for installation?

When mounting the wall plate, allow at least 140 mm to the right, 15 mm to the left, 30 mm above and 100 mm below the upper left corner to allow installation of the plug-in module.

Can the RT51 thermostat control multiple zones?

The single RT51 controls only one zone. For multiple zones, use RX2 or RX3 receivers with the RT51-RF or RT52-RF model, allowing management of up to 3 independent zones with separate pairings.

How to reset the RT51 thermostat?

Open the front cover, remove the batteries for at least 2 minutes, then reinsert them. The screen will display default settings (DAY mode). You will then need to reprogram the temperatures and clock if necessary.

USER MANUAL RT51 DANFOSS

Electronic room thermostat with manual or automatic Day/Night set-back

Certification Mark

Installation Instructions User Instructions

Installation Instructions

Please Note:

This product should only be installed by a qualified electrician or competent heating installer and should be in accordance with the current edition of the IEEE wiring regulations.

Product Specification

Thermostat features RT51/52 RT51/52-RF
Power supply 2 x AA/MN1500/LR alkaline cells
Memory back-up 1 min. for battery change
Switching action of output relay 1 x SPDT, Type 1B N/A
Switch rating of relay contact 3(1)A, 10-230Vac N/A
Transmission frequency (RF model) N/A	433.92MHz
Transmitter range (RF model)	N/A	30m max
Temperature range	5-30°C
Dimensions, mm	110 wide, 88 high, 28 deep
Design standard	EN60730-2-9 (EN300220 for RF)
Rated impulse voltage	2.5Kv
Ball hardness test	75°C
Control pollution situation	Degree 2
Temperature accuracy	±1°C

Important note RF products: Ensure that there are no large metal objects, such as boiler cases or other large appliances, in line of sight between the transmitter and receiver as these will prevent communication between thermostat and receiver.

☐ First, remove the wallplate from the back of the unit.

From the top left hand corner of the wallplate, there must be clearances of at least 140mm to the right, 15mm to the left, 30mm above and 100mm below in order to mount the plug-in module.

☐ Prior to mounting the unit should be set in either ON/OFF or chrono-proportional control mode (see below).

ON/OFF - boilers switches ON when below set temperature and OFF when above.

Chrono-Proportional - energy saving feature which fi res the boiler at regular intervals to maintain a set temperature, achieving a constant ambient environment for the user.

Some existing thermostats will have a Neutral wire and/or Earth wire connected. These are not required by the RT51/52 and must NOT be connected to any RT51/52 terminals. Instead they should be made electrically safe and coiled in the recess at the back of the RT51/52.

Installation Instructions

RX Receiver Wiring (RF models only)

RX1

graph TD
    A["ELECTRONICS"] --> B["N"]
    A --> C["L"]
    A --> D["1"]
    A --> E["2"]
    A --> F["3"]
    A --> G["4"]
    H["COM"] --> I["ZONE 1 ON"]
    J["ZONE 1 OFF"] --> K["Line with open switch"]

RX2 & RX3

graph TD
    A["Electronics"] --> B["N"]
    A --> C["L"]
    B --> D["COM"]
    C --> D
    D --> E["ZONE 1 ON"]
    E --> F["ZONE 1 OFF"]
    F --> G["ZONE 2 ON"]
    G --> H["ZONE 3 ON"]
    H --> I["TERMINAL 6 RX3 ONLY"]

NB. For mains voltage operated systems link terminal 2 to mains live supply.

If the thermostat and the receiver have been supplied together in a combined pack, the units have been paired in the factory and no commissioning is required (RX1 only).

To tune the RX receiver to the frequency of the thermostat signal, follow steps 1-5 below.

Step 1 RT51/52-RF

Reset the unit by removing the batteries for 2 minutes, then replace.

Step 2 Press and hold V and + buttons for 3 seconds (Thermostat now transmits unique signal continuously for 5 minutes).

Step 3 RX1

Press and hold buttons PROG and CH1 for 3 seconds until green light fl ashes once.

Step 4 RX2 (if applicable)

Stat 1 - perform steps 1-3.

Stat2-wait 5 mins, perform steps 1-2 and then press PROG and CH2 on RX2.

RX3 (if applicable)

Stat 1 - perform steps 1-3.

Stat 2 - wait 5 mins, perform steps 1-2 and then press PROG and CH2 on RX3.

Stat 3 - wait 5 mins, perform steps 1-2 and then press PROG and CH3 on RX3.

Step 5 RT51/52-RF

Press or V to select temperature - unit will revert back to operating mode.

What is a programmable room thermostat?

... an explanation for householders

A room thermostat simply switches the heating system on and off as necessary. It works by sensing the air temperature, switching on the heating when the air temperature falls below the thermostat setting, and switching it off once this set temperature has been reached.

Turning a room thermostat to a higher setting will not make the room heat up any faster. How quickly the room heats up depends on the design of the heating system, for example, the size of boiler and radiators.

Neither does the setting affect how quickly the room cools down. Turning a room thermostat to a lower setting will result in the room being controlled at a lower temperature, and saves energy.

The heating system will not work if a time switch or programmer has switched it off.

The way to set and use your room thermostat is to find the lowest temperature setting that you are comfortable with, and then leave it alone to do its job. The best way to do this is to set the room thermostat to a low temperature – say 18°C – and then turn it up by one degree each day until you are comfortable with the temperature. You won't have to adjust the thermostat further. Any adjustment above this setting will waste energy and cost you more money.

If your heating system is a boiler with radiators, there will usually be only one room thermostat to control the whole house. But you can have different temperatures in individual rooms by installing thermostatic radiator valves (TRVs) on individual radiators. If you don't have TRVs, you should choose a temperature that is reasonable for the whole house. If you do have TRVs, you can choose a slightly higher setting to make sure that even the coldest room is comfortable, then prevent any overheating in other rooms by adjusting the TRVs.

Room thermostats need a free flow of air to sense the temperature, so they must not be covered by curtains or blocked by furniture. Nearby electric fires, televisions, wall or table lamps may prevent the thermostat from working properly.

Your room thermostat

RT51

The RT51 is a simple to use room thermostat which allows you to programme a Day and a Night temperature, and to switch between the two settings simply by pressing 2 buttons.

RT52

The RT52 has the same functionality as the RT51 with the added benefit of a built-in timer, which will return the thermostat to Day temperature at a time chosen by you.

Wireless RF versions

Both models are available in wireless versions - RT51-RF and RT52-RF - which offer exactly the same functions as the hard-wired models.

Each thermostat communicates with an RX receiver, which can be located up to 30m away.

Reading your display

Before you start

To reset the unit, open the fl ap on the front of the programmer. Remove the batteries for 2 minutes, then replace.

The display will automatically default to DAY mode (d shown top left of display) and show actual temperature in the large characters and required temperature in the smaller characters.

Setting the DAY & NIGHT temperatures

DAY temperature

Use the ▲ and ▼ buttons until the required DAY temperature is shown.

Simple line drawing of a hand pointing at a circular object with an arrow indicating direction (no text or symbols)

NIGHT (set-back) temperature

Press ▲ and ▼ buttons together once to select NIGHT mode (n shown top left of display).

Use the ▲ and ▼ buttons until the required NIGHT(set-back)temperature is shown (between 5-30°C or Off).

Pressing the ▲ and ▼ buttons together once allows you to toggle between DAY and NIGHT mode as required.

RT52 / RT52-RF only

Setting the clock

Press PROG button once.

Use ▲ and ▼ buttons until the correct TIME is shown.

Setting the Return to Day Time

Press PROG button again.

Use ▲ and ▼ buttons to select the time you wish the unit to return to DAY mode.

RUN Mode

Press PROG again to return to RUN mode.

The unit will now control your heating at the temperatures you have set.

Battery Replacement

☐ When batteries are low a battery symbol will flash in the LCD display.
☐ You have 15 days to replace the battery before the unit will switch off.
☐ When changing batteries, remove old batteries and insert new ones within ONE MINUTE and programming will not be lost.

IMPORTANT: always use high quality alkaline batteries.

NB. If the display ever goes blank during normal operation, the batteries will need to be renewed, the unit reset and the time and programmes reset.

●

Diagram showing a hand inserting a cable into a device casing, with no visible text or symbols.

Diagram of a device rear panel showing internal wiring and ports (no text or labels)

Diagram of a device with wires and connectors, no text or symbols present

Etape 3 RX1

Simple line drawing of a hand holding a magnifying glass, with no text or symbols present.

Diagram showing a hand inserting a cable into a device casing, with no visible text or symbols.

AUS COM EIN

Diagram of a device rear panel with cable and connector (no text or symbols)

Diagram of a device with wires and connectors, no text or symbols present

Simple line drawing of a hand pointing at a circular object with an arrow indicating direction (no text or symbols)

RUN-Modus

Line drawings showing hand holding a device with a cable being inserted, and three views of the device (no text or symbols present)

Diagram showing a hand inserting a small electronic component into a device casing (no text or symbols present)

Simple line drawing of a hand pointing at a circular object with an arrow indicating direction (no text or symbols)

La Temperatura nocturna

Fijar Volver a la Temperatura diurna

Modo en FUNCIONAMIENTO ("RUN")

Diagram showing a hand inserting a cable into a device casing, with no visible text or symbols.

Simple line drawing of a hand holding a magnifying glass, with no text or symbols present.

NATTE (tilbagestilling)-temperatur

DRIFTS-tilstand

Line drawings showing a hand inserting a device into a smartphone case, with no text or symbols present.

Diagram showing a hand inserting a small electronic component into a device casing (no text or symbols present)

Two technical diagrams showing internal wiring connections on a device casing, with no visible text or symbols.

Simple line drawing of a hand pointing at a circular object with an arrow indicating direction (no text or symbols)

NACHTTEMPERATUUR

Normaal bedrijf

Line drawing of hands inserting a device into a device (no text or symbols)

Three line drawings of hands holding open and closed smartphones, showing internal components (no text or symbols)

Diagram showing a hand inserting a small electronic component into a device casing (no text or symbols present)

Diagram of a device rear panel with cable and indicator lights (no text or symbols)

Diagram of a device with wires and connectors, no text or symbols present

Simple line drawing of a hand pointing at a circular object with an arrow indicating direction (no text or symbols)

Line drawing of hands inserting a card into a device (no text or symbols)

Three-step line drawings of hands holding a device, showing internal components and assembly (no text or symbols)

Diagram showing a hand inserting a cable into a device casing, with no visible text or symbols.

Two technical diagrams showing cable installation on a device casing, with no visible text or symbols.

Simple line drawing of a hand pointing at a finger with an arrow indicating direction (no text or symbols)

Temperatura nocna

Tryb RUN (praca)

Diagram showing a hand inserting a cable into a device casing, with no visible text or symbols.

1) ON/OFF

2) CHRONO

Two technical diagrams showing internal wiring connections in a device casing, with no visible text or symbols.

RX imtuvo laidai (tik RF modeliams)

RX1

graph TD
    A["ELECTRONICS"] --> B["N"]
    A --> C["L"]
    A --> D["1"]
    A --> E["2"]
    A --> F["3"]
    A --> G["4"]
    H["COM"] --> I["ZONE 1 ON"]
    H --> J["ZONE 1 OFF"]

RX2 & RX3

graph TD
    A["Electronic"] --> B["A"]
    A --> C["B"]
    A --> D["C"]
    A --> E["1"]
    A --> F["2"]
    A --> G["3"]
    A --> H["4"]
    A --> I["5"]
    A --> J["6"]
    K["N"] --> L["L"]
    M["COM"] --> N["ZONE 1 ON"]
    O["ZONE 1 OFF"] --> P["ZONE 2 ON"]
    Q["ZONE 3 ON"] --> R["ZONE 6 RX3 ONLY"]

Simple line drawing of a hand pointing at a warning symbol with an exclamation mark (no text or labels)

RUN režimas

Diagram showing a hand inserting a cable into a device casing, with no visible text or symbols.

Two technical line drawings of a device rear panel with cable and terminal connections (no text or symbols)

Simple line drawing of a hand pointing at a circular object with an arrow indicating direction (no text or symbols)

Modalità RUN

www.danfoss.com/BusinessAreas/Heating

This product complies with the following EC Directives:

Electro-Magnetic Compatibility Directive.

(EMC) (89\336\EEC), (92\31\EEC)

Low Voltage Directive.

(LVD) (73\23\EEC), (93\68\EEC)

CE