I recently moved into a rental property with under-floor heating. There was no user manual and no indication what make/model the heating system was.

After substantial investigation, I found the device pictured was a Devireg 710 made by "Devi".

The user manual for the 710 was not online, so I spoke to a technician who emailed me the documents; I have attached them here in the hope they will help someone else.

Read on to the following steps to see some tips about how to configure such a system.

Step 1: Understanding the System

The Devireg 710 is VERY un-intuitive to use! Here is a brief description of the general way the system functions - once you understand this, you will be better able to understand the best knob settings for your setup.

There is a temperature sensor both inside and outside your house
The Devireg works to keep the inside temperature at some nominal value (e.g. 20degC) when the outside temperature is at some baseline temperature.
This function is limited only be a configurable maximum under-floor temperature.
The outside baseline temperature should probably not be altered. It is set at the time of installation of the system and is a function of the installation materials and geographic location. E.g. around 4degC is a 'normal' setting for southern UK.
The nominal indoor temperature can be offset depending on your personal preferences and can have separate settings for the morning and evening.

See the next step for information about each specific knob.

Step 2: Understanding the Knobs

There are 4 knobs on a Devireg 710 and 2 LEDs. (See attached documents for official explanation)

DAY
- This knob determines the offset from the nominal indoor temperature that you would like for the period in the afternoon/evening. Whether of not this setting changes anything for you will have more to do with your individual energy metering - if you have an off-peak only connection to your Devireg then this setting is irrelevant.
- Remember that "0" isn't 0 degrees, it is simply saying that you are happy with the default temperature. If you want it it a bit cooler (by trial and error) then bump it down to -1 or -2 and see if you like it that way during the next 24hr period.
- The "Const" setting is technically a test mode. It can be used when first switching your floors on for the winter. It keeps the heat constantly on for the period where the floors are first warming up. Use it for the first day or two after initialisation, then switch back to "0" and see how you like it.
NIGHT
- Same as "DAY", but without the "Const" setting. This controls the offset to the default temperature that you will experience when first waking up in the morning. Bump it up or down from zero on a trial-and-error basis.
Limit
- Sets the maximum temperature setting the floors can experience. This means that even if it is very cold outside and you have set DAY or NIGHT to a relatively high setting (or Const) the floor may switch off due to the floor itself being too hot, even though it hasn't heated the room to your desired setting yet.
- This can be handy if you have a more thermally conductive floor surface (such as tiles compared to carpet) which can become too hot to comfortably stand on at higher temperatures.
E1
- The most confusing of all settings, this is not intended to be altered by the end-user (hence the recessed knob).
- This is set depending on the materials involved during the floor installation and the temperature ranges in your geographic location.
- Generally, when the outdoor temperature reaches this value, the indoor temperature should reach the nominal indoor temperature (or offset thereof).
LED (near Limit)
- This LED is green when the system is powered but not actively heating.
- The LED will change to red when the floor is actively heating
- If the LED switches off completely, the system is being forced off by the Limit knob setting (or you have lost power to your property)
LED (near NIGHT)
- This LED flashes with a duty cycle in proportion to the power being output to the heating system (fully on would mean it is putting out 100% power, equal time off and on would mean 50% power etc.)

Step 3: Operation Tips

General guide for setup and general operation

Set DAY to "Const" until heat has penetrated floors (may take over one day)
Set DAY and NIGHT back to "0" to see if the nominal temperature is acceptable.
- Bump up or down on a trial-and-error basis to get perfect value. Do not adjust more often than once every 24hrs, or you won't really know.
Set limit to around 50deg. If this leads to floor surfaces being too hot or cold even though the air temperature is pleasant, bump it up or down by 5deg.
Don't adjust E1 unless you feel it was certainly set incorrectly when installed. This could happen if the installer was following a rule of thumb which has proved to be incorrect if the outdoor sensor is installed in a location on your house which leads to the sensor not experiencing environmental conditions representative of the actual outdoor temperature.