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How to set a Danfoss thermostat

Updated: October 2026

The head is already on the radiator, or the wall stat is already on the plate, and the number in front of you looks as if it ought to mean one temperature in every Danfoss booklet. It does not. This guide on how to set a Danfoss thermostat uses the card for your model, then the place a wall stat should sit, then the limits of the Eco app. It is not a buying ranking. If the head will not click on, go to [Danfoss RA or M30](/hub/thermostats/danfoss-thermostat/sub/danfoss-thermostat-ra-or-m30). The products themselves are on the [Danfoss thermostat comparison](/hub/thermostats/danfoss-thermostat). We did not measure your room. A purchase through our links can earn a commission at no extra cost to you.

The head is already on the radiator, or the wall stat is already on the plate, and the number in front of you looks as if it ought to mean one temperature in every Danfoss booklet. It does not.

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Danfoss Danfoss Redia RA click

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Danfoss Danfoss Redia RA click
9.6/10about £16.99
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Danfoss Danfoss RAS-C2

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Danfoss Danfoss RAS-C2
9.4/10about £30.18
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Danfoss Danfoss Eco 014G1115

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Danfoss Danfoss Eco 014G1115
7.6/10about £33.95
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On this page
  1. 1.The number on a liquid head
  2. 2.What the dial does not do
  3. 3.Where a wall stat sits
  4. 4.The Eco schedule

The number on a liquid head

Danfoss prints more than one scale. One householder card, BC297345792743en-GB, shows positions 1 to 5 near 8, 12, 16, 20 and 24 °C. Another leaflet, AN000086404883, prints position 3 at about 20 °C. They are not the same card, so number 3 is not one Celsius figure for every Redia or RAS-C2. Use the card that came with the head. If it is missing, start from a mid number and judge the room after a normal evening, not after ten minutes. On a click head, UK reviews of the Redia describe setting the dial to 5, pushing the head on, then turning it back. That sequence is about mounting, not about asking the boiler for more heat. Frost protection is the low end of the scale. The householder card’s position 1 sits near 8 °C, and manufacturer data for the Redia and the RAS-C2 quotes about 8 °C to 28 °C. That span is a product range, not a promise the bedroom will hold 20 °C. Set the lowest comfortable number and leave it. The Redia listing claims an 18-minute response. The room will not leap to the new setting in the time it takes to turn the dial.

What the dial does not do

A higher number does not heat the room faster. Position 5 asks that radiator to stay open until the sensor is satisfied at a higher temperature. The speed still comes from the boiler, the pump and the size of the radiator. If the wall thermostat is already satisfied, turning a bedroom head from 3 to 5 will not restart a boiler that has switched off. The head only limits the radiator it sits on. It does not prove a 30% or 40% cut in the bill. Those percentages are listing claims on the Eco and the RAS-C2. If the radiator stays cold at a mid setting while other rooms heat, the pin may not be moving, or the lockshield may be shut. Give a changed setting an evening before you move it again.
Danfoss Danfoss Redia RA click

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Danfoss Danfoss Redia RA click
9.6/10about £16.99
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Where a wall stat sits

BEAMA’s siting note puts a room thermostat at about 1.5 m, in free air, not above a radiator, and not in a room that already has thermostatic radiator valves. Above a radiator, in a draught, behind a curtain or in a cupboard, it will satisfy too early or too late. The room that contains the wall stat should not also contain a TRV that can close and fool the sensor. That split is the point of the room thermostat or TRV page. TP5000Si reviews in this set describe a swap onto the existing backplate. A holiday setting on that model is adjustable, against a fixed 5 degree setback that reviewers mention on an older TP5. If you do not know the conductors, stop and use a competent electrician. This page does not give 230 V terminal steps. The RET2001 listing does not state a voltage.

The Eco schedule

The Eco, code 014G1115, at £33.95, is the programmable head in this set. The Danfoss data sheet allows up to three setback periods a day. One UK review says the app only offered two temperatures, so trust the screen in front of you. Danfoss support says that if you want adaptive start to cope, keep the gap between away and home to about 4 °C. The bullets say Bluetooth at about 10 m. UK reviews say the link is slow unless you are close, or you press the button or turn the ring. The ring still works by hand. Before the head goes on, the valve pin must push in and spring back. If it stays down, or the valve is weeping, do not force the head on. It will not change the heating from work. If you are still choosing between a liquid head and this app, the buying guide is the decision. The rest of the house still follows the wall stat.

Common questions

What temperature is number 3?
It depends on the card. One Danfoss leaflet prints position 3 at about 20 °C. A householder card prints positions 1 to 5 near 8, 12, 16, 20 and 24 °C, so the same numeral can sit next to a different figure. Use the insert for your model. If you do not have it, start at a mid number and judge the room after a normal heating period.
Will a higher number heat the room faster?
No. A higher number keeps that radiator’s valve open until a higher temperature at the sensor. The boiler, the pump and the size of the radiator set the speed. If the wall thermostat has already turned the heating off, a head on 5 cannot override it.
Where does the frost mark sit?
At the low end of the scale on your card. The householder card’s position 1 is printed near 8 °C, and Danfoss data for the Redia and RAS-C2 quotes about 8 °C to 28 °C with frost protection. Another leaflet does not use that same row, so follow the mark on the head you own rather than a single remembered number.
Where should the wall thermostat go?
About 1.5 m from the floor, in free air, not above a radiator, not in a draught, and not in a room that already has TRVs. That is the BEAMA siting note. If the existing TP5000 plate is already in a sensible room, a like-for-like swap can stay there. Unknown wires are an electrician’s job.
How many periods can the Eco app set?
The Danfoss Eco data sheet says up to three setback periods a day. A UK review of this listing says only two temperatures could be set. Trust the screen in front of you. Danfoss also suggests keeping the away and home temperatures about 4 °C apart if you want adaptive start to cope.
What do I check on the valve pin before the new head goes on?
Press the pin. It should push in and spring back. A UK Eco review flags that check before fitting. If the pin stays stuck, or water appears at the valve, stop. Forcing a click head or an Eco adaptor onto a seized pin will not repair it, and draining the system is a job for a heating engineer.

Related pages

Frost protection and holiday mode

Danfoss thermostat

Best Danfoss radiator thermostat for a spare RA head

Danfoss thermostat buying guide: head, Eco or wall

Danfoss RA or M30: which radiator head will mount

Room thermostat or TRV and the England boiler pattern

Sources

Public UK sources for Approved Document L, BS EN 215, Danfoss product data, and Part P. Listings are the amazon.co.uk captures for these seven ASINs, not a live reload on 17 October 2026. Prices on amazon.co.uk move.

  1. BEAMA Part L 2022 heating controls (retrieved 17 October 2026)
  2. Danfoss GB, Part L (retrieved 17 October 2026)
  3. BSI, BS EN 215:2019 (retrieved 17 October 2026)
  4. Danfoss Eco data sheet (retrieved 17 October 2026)
  5. Danfoss Eco support (retrieved 17 October 2026)
  6. Danfoss RAS-C2 013G6040 (retrieved 17 October 2026)
  7. Danfoss Redia 015G5120 (retrieved 17 October 2026)
  8. IET Part P FAQ (retrieved 17 October 2026)