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With no steering system, the central heating of this house is now equipped with wireless regulation. The goal: to save money without major work.

install programmable heads on radiators

Necessary material

  • Flat and / or thumb keys
  • Electrician's screwdriver
  • Wire stripper
  • Drill
  • screwdriver
  • PH tester
  • Bucket
  • 4 thermostatic bodies
  • 4 HR92 programmable heads
  • Evohome touch controller
  • Control module (boiler)

Difficulty: 2/4
Cost: Pack communicating from 384 €. Kit from 96 € for a programmable head or 327 € for 4 programmable heads
Time: 1/2 day

Heating is one of the most important things you can do to save money. Here, the chosen solution consists of equipping the existing central heating system (a De Dietrich gas boiler over 10 years old) with a zone-by-zone control system. Most manufacturers of regulation offers this type of wireless solutions (Danfoss, Comap, Siemens, Giacomini...).

Adaptation to the existing

The kit chosen here prevents owners from making any holes. It includes three programmable thermostatic heads with digital display, a multi-zone programmable touch screen thermostat (Honeywell's Evohome) and a relay (connected to the boiler). The elements communicate with each other by radio transmission.
Main advantage: the system independently manages the temperature of parts considered as distinct areas. The installation of this device requires the connection of a relay to the boiler and the replacement of the thermostatic heads of each radiator if they are already equipped with a thermostatic body. In the opposite case, the simple body must be removed to install a thermostatic body.
The intervention requires turning off the boiler and partially emptying the circuit (half of the radiators for example). This operation is an opportunity to check the condition of the water in the circuit). Owners, the owners here have chosen a scalable kit: they can add up to twelve thermostatic heads to equip other parts remaining to develop.

An evolutionary system

operation of programmable heads

The heads operate either independently (they are equipped with a thermostat) or coupled to the Evohome thermostat which then takes control, although it is always possible to intervene on each of them. The system also makes it possible to integrate an Internet gateway to pilot the installation remotely via a smartphone or a tablet (with the application of the manufacturer).

Changing the radiator valves

open the drain cock

  • After switching off the boiler, open the drain cock previously connected to a hose (eg watering hose) with the other end in a bucket.

Info for DIYers

pH check

The draining of the heating circuit makes it possible to diagnose the state of the network.
Check the pH which should be around 7 (neutral).
Below, the water is acidic and can cause corrosion; above, it is basic, so there can be creation of sludge.
Depending on the case, it is necessary to carry out preventive or curative maintenance.

dismantle stopcocks

  • Once the volume of water has drained (visible on the pressure gauge), remove the shut-off valves with two flat wrenches, first releasing the radiator-side nut.

application of sealing tape

  • Apply sealing tape to the threads (teflon or tow: minimum 3 turns in the thread direction).
  • Fit the new body ending with the radiator side nut.

preparation of the thermostatic valve

  • Prepare the thermostatic valve by inserting the two batteries supplied LR6 type AA.
  • Then turn it on to check that it is working properly.

install the radiator heads

  • Place the head on the thermostatic body and secure it by pushing the lock button located behind the screen.
  • Equipping all radiators in the same way.

Connection of the relay on the boiler

remove the protective cover

  • Remove the protective cover from the electrical circuit of the boiler.
  • Here, it contains the markings of the terminals; so we put it on sight and on the spot.

wire connection

  • Connect the brown (line) and blue (neutral) wires to the boiler power terminals.
  • The black wire is connected to a terminal dedicated to the room thermostat (TAM).

install the case

  • To attach the relay to the wall, remove the housing, place the base on the wall and locate the holes.
  • Drill, put ankles and screw the base.

Turning the system on

check of purge valves

  • Make sure all radiator bleed valves are properly closed.
  • Start filling the network by opening the dedicated valves.

System Tip D

check the circulator

To make sure the circulator is working properly, check if the body emits (small) vibrations. For this, simply put a screwdriver and listen if the pump makes a noise.

check the manometer

  • During filling, check the manometer.
  • Refer to the recommendations of the boiler manufacturer for the exact value to be met.

purge the radiators

  • It is now necessary to purge the radiators to eliminate the air contained in the circuit.
  • Slowly unscrew the bleed valve with a screwdriver and let the air escape.

configure the thermostat

  • Switch to multizone thermostat configuration by combining all programmable faucets with the touch terminal according to the manufacturer's instructions.


Video Instruction: How to change a radiator valve for a thermostatic one. Save money on heating bills.