Questions:

Answers:

What is the  price per m2?

The price depends on the size of the room, available floor space and system type (whether the system is to be used as the only heating source or as a warm floor).
E.g.: 5 m² bathroom with shower would normally require a 4 m² devimat™ and devireg™ thermostat. Dimensioning of a total heating requires contact to your DEVI™ partner in your area.
Electrical floor heating normally costs less in purchasing and installing costs than any other conventional heating system. General rule is: the bigger the installation area is, the lower is the system price per square metre.

How much energy does it consume?

This depends on the purpose of the installation and is directly related to the heat loss from the building/room. To ensure the optimal comfort and minimal energy consumption we propose to use thermostat devireg 550.
E.g. for total heating in a normally insulated room (typical climatic region in Denmark) the energy consumption will be less than 50 kWh/m² per heating season.

Doesn’t it cost a small fortune to heat with electricity?

We do not have influence on electricity prices , but we make sure, with help of design and products like devireg 550, that DEVI intelligent floor heating systems spend only the energy needed to create the comfort people are demanding.
As example: for supplementary heating (warm floor only) the consumption/cost is app. half the cost of total heating, additionally you save equal proportion on energy costs from other heating source.
For total heating, yearly energy consumption for heating purposes (see above example from Denmark) needs to be timed by the kWh price in your country.

How is electrical floor warming system in comparison with other heating options? 

When comparing different heating systems, you must compare the full costs of of the systems (not just the price for one kWh of consumption), viz.:
- the complete investment, i.e. the purchase costs for the systems
- the complete installation costs
- the lifetime of the system
- the maintenance costs per year
- the running costs (converted to kWh or GJ)
- the depreciation on the investment

With the above parameters taken into consideration, we are sure you come up with a conclusion in favour of electrical floor-warming system.

Is it safe?

It is safe and approved by the local approval institutes for use in houses, apartments, and other facilities. Safety is ensured by the high quality, reliable construction of the cables and installation in accordance to building standards.

The heating conductor is insulated first by a layer of insulation, and then surrounded by a screen that is earthed, and finally protected by an outer layer of insulation.  The earthing is in most countries obligatory to connect to a 30mA faulty current relay (RCD) .
There exist international standards in regard to construction of electrical heating cables, and DEVI™ products are designed in accordance to those.
Electrical installation is conducted and formed in accordance with the building and electrical standards in the respective country, making the electrical floor heating a safe heating system for heating of houses and outdoor areas.

The system has been widely used in north-western European countries for more than 30 years.

Can it be used in wet rooms?

Yes! DEVI cables and mats are watertight and high-voltage tested during production. As separate test, the cables/mats are placed in a water basin, for several hours.
DEVI™ cables are fitted with sheath connected to earth for electrical protection.
For additional safety a faulty-current relay (RCD relay) is in most countries obligatory and required by electrical regulations for household electrical installation.

Are tiles the only surface I can use DEVI™ floor heating system under?

You can use any type of flooring on top of DEVI™ floor heating system. Linoleum and wood is often used.  The maximum heat resistance value of the floor covering material is 0,125 m² ºC/W which equals approx. 30mm hardwood. Please remember to contact your local wooden floor or carpet dealer regarding details.

Does it need special building materials, like special cement or concrete?

Home improvement (new floor on top of old one):
A common way is to make the setting coat very thin, on existing floor surface, by using special thin-floor mastics, allowing it to cover the cables/mat completely. These mastics are just high quality cement with some plastificators added for elasticity.  Ask in your local building material shop, or ask our closest dealer.

New construction:
No extra expenses are necessary, only installation of heating cables/mats in any type of concrete.  Our dealer will support with a heat loss calculation to determine the needed output per m².

How much total power should be installed?

The theoretically calculated heat loss must be compensated as with any heating system.  Owing to the inertia of a floor-warming system, we recommend to install 30% more than the theoretical demand. Owing to the thermostat regulation, it will not consume more energy, just act quicker in raising the temperature. 
For supplementary/comfort heating 60W/m² is usually sufficient to keep floors warm to walk on. However, the output to install must be sufficient to ensure the uniform floor temperature and avoid to feel cold and warm areas. Our home improvement thin mats ensure this and with our cables embedded in concrete the max. distance between cable loops is upto 20 cm in 5 cm depth.

Can it be a main source of heat?

Yes, as long as calculated heat loss does not exceed ~120 W/m².  If this is the case we recommend to increase insulation value of building materials used to bring down the heat loss,  or to have supplementary heat source along with the floor warming systems.  Your DEVI™ partner in the area will guide you.

How much insulation do I put in the floor?

Insulation (roof, walls, etc.) is a very important issue for all heating systems to save on the energy bill, and for floor-warming systems the floor insulation is of special importance.  The local building norms must be followed in this respect and they are improved in all countries runningly.
To illustrate the importance:  With no floor insulation you loose approx. 30% of your installed output downwards.  With the Danish prescribed building standards today of 150mm polystyrene (0,04 W/mºC), the percent downwards will be about only 4%.

What happens if the cable stops working and I cannot pull it out, is my money then wasted?

Once DEVI™ product (heating cable or mat) is installed as prescribed, failures are very rare. If a fault occurs, it would be, as a rule, caused by mechanical damage, like a nail or drilling. In this case the fault is easy to locate. Concrete immediately above the fault is removed to get access to it, then the broken part is cut out and the cable ends are securely connected together and insulated by means of a special repair set. This is a simple and quick operation securing a well working heating system.
If the fault is due to a production error, is it nice to know that DEVI™ offers 10 years manufacture guarantee on devimat™ and deviflex™ heating cable and 2 years on the devireg™ fully-electronic thermostats.
In some complicated cases, a fault can be located with the help of a devitector™ device (fault finding device for electrical heating cables).
Under all circumstances, in accordance with our complaint handling procedure, an authorised DEVI™ partner must be contacted, and they will help to secure a re-establishment of normally working system.

Are there harmful electro-magnetic fields?

All electrical equipment and installations have electro-magnetic fields (EMF). Measurements of EMF from floor-warming system show values far below the hygienic limit values established. As example, it is ten times less from a floor with heating cables than from the monitor of a PC.
Furthermore, DEVI™  systems for room heating are delivered standard as twin-conductor heating cables where the conductors are ‘neutralising’ the EMF down to a further 10% of the already very low value.
You may always ask our partner for information on EMF measurements.

What is the temperature:
1. In the room?

2. On the floor?

3. On the cable?

1. As you desire, normally, around 20°C, but can also be both higher and lower.

2. As you wish, normally around 22-27°C, and most people prefer higher temperature in bathrooms. Some European countries have maximum allowed floor tempetures included in building regulations which we support for the human perception of comfort, which is 28°C on tiles and max. 27°C on wood.

3. Around 30-45°C normally.  (Max. 65ºC operation temperature according to approval norms.)

Do I get thick legs from walking on the floor?

No, this is a thing of the past when the floor-warming systems, mostly water heating systems, could not be well controlled to ensure a uniform and low temperature heating system.   You could then feel where the pipes were placed – this is not the case with a well-designed and well-regulated floor-warming system.   Today, with improved building standards (see other question on insulation) the difference between temperatures at floor and head level should be reduced to 7-8 degrees maximum.

Who will install it?

We can recommend authorised installers. Please contact your local DEVI™ company and we will be glade to recommend installers close to your home.

Can I install it myself?

You can lay the devimat™ yourself following our installation instruction closely. An authorised electrician must always make the main electrical connection.
A professional should install deviflex™ heating cables. (Observe this point in accordance with national regulations).

What is the lifetime?

DEVI™ has been producing heating cables for around 40 years and there have been no cases, to the best of our knowledge, of a system malfunction due to ageing.
The lab simulations suggest a lifetime of at least 50 years.
Basically, we can say that the heating cables embedded in concrete will last at least as long as the normal hidden electrical wiring in an apartment.

Is it healthy with a floor-warming system?

Yes, the floor-warming systems are clean and healthy because the heat flows up from the floor instead of air being circulated in standard radiator system.
It is good for allergies and recommended by the Asthma Foundation in several countries. 

Can I switch it on and off manually?

Yes. If you are going for long summer holidays, you may choose to switch the system off by a manual switch. But when switched back on, a thermostat must control the system.

What about the environment?

DEVI™ floor heating system uses energy in a more efficient manner than traditional radiator heating, due to the thermal comfort and optimal heat distribution,  and the now developed intelligent devireg™ thermostats with timer enhances the energy efficiency further so that DEVI™ floor heating system will use approx. 10-15% less energy to achieve thermal comfort surpassing that of water based radiator system and does it with an equally reduced strain on the environment.
Electricity is a clean and ecological heating source, which can be produced in different ways depending on the geographical conditions, including windmills, hydropower, solar cells, etc.