How to Choose an Electric Convector: Power, Control and Other Criteria
How to choose an electric convector heater: output, control and other criteria
An electric convector heater is one of the simplest heating solutions available – you buy it, plug it into a socket or connect a fixed supply, and the room warms up. No plumbing company, no boiler, no piping. Despite this apparent simplicity, in practice we see dozens of cases where people chose a convector with unsuitable output, poor control, or the wrong design – resulting either in an oversized unit that unnecessarily overheated a small room and wasted energy, or an undersized one that only struggled to reach temperature and wasn't enough even in winter. This article will guide you through all the important selection criteria so that you make a decision that will work well for years to come.
What is an electric convector heater and how does it work
An electric convector heater is a heating body that warms air by passing it through a glowing resistive element. Air enters through a grille at the bottom of the unit, passes around the heating element, warms up, and rises upward through natural convection (warm air rising), where it leaves the unit. Some models also have a small fan that boosts this airflow and speeds up heating – these are known as fan convectors, although a standard convector has no fan and operates purely on the principle of natural convection.
Understanding this mechanism is important because it directly affects where a convector is suitable and where it is not. Natural convection heats the air in the room evenly, doesn't stir up dust (unlike fans and hot-air units), and works quietly. It's ideal for living rooms, bedrooms, children's rooms, and offices. It's less suitable for very high spaces (warm air rises to the ceiling), where you would need an additional circulation solution.
First step: determining the required output
Output is undoubtedly the most important parameter when choosing a convector heater. Too low an output means the unit will run at full power the entire time, will not reach the desired temperature, and will shorten its service life. Too high an output is less dangerous, but unnecessarily expensive to buy and operate, since the control will keep switching the unit between full power and off.
The basic rule of thumb we use in practice: 50–80 W per square metre of floor area for a well-insulated room in a typical family house or apartment in a residential building. For older, poorly insulated spaces, corner rooms, spaces with large windows, or attics, allow 80–120 W/m². For an excellent new low-energy building, 40–50 W/m² may be sufficient.
Specific examples from practice: a 5 m² bathroom in a panel building apartment – 500 W is enough. A 20 m² living room in a family house from the 1980s without heat recovery ventilation – you need 1500 to 2000 W. An 8 m² hallway in a new building – 500 W will suffice. A 12 m² children's room with one external wall and a plastic window – optimally 1000 W.
A more detailed calculation procedure, including ceiling height, number of windows, orientation to the compass points, and heat loss coefficients, can be found in the article What output electric convector heater do I need for my room in our Knowledge Centre. Here we only present the basic figures so we can move on to the other criteria.
Overview of available output classes and their use
Electric convector heaters are typically manufactured in several output classes, and for common living spaces these models cover almost all situations:
- 500 W – bathrooms, toilets, small hallways, minor storage rooms, supplementary heating for a smaller room. Example: the Protherm 500 is a compact unit ideal for exactly these purposes.
- 1000 W – children's rooms, bedrooms, small offices, larger bathrooms, or medium-sized hallways. The Protherm 1000 covers most standard bedrooms in a panel-building apartment.
- 1500 W – rooms of 15–20 m² in well-insulated houses, living rooms, more open spaces. The Protherm 1500 is the most popular output level for the living room of a smaller family house.
- 2000 W – large living rooms, offices with multiple windows, corner rooms, poorly insulated spaces. The Protherm 2000 is the maximum output that can still be plugged into a standard 230 V socket without special modifications to the electrical wiring.
An important note regarding the electrical installation: 2000 W at 230 V draws 8.7 A. A standard 10 A or 16 A circuit breaker handles this without any problem. However, when combining several convectors on one circuit, watch the total draw – if you have 3× 2000 W convectors in an apartment, that's 26 A just for heating. In such a case, consulting an electrician and possibly setting up separate circuits is essential.
Control: the heart of every convector heater
Many buyers decide based only on output and price, but control is the parameter that determines everyday comfort as well as the size of the electricity bill. Poor control is in practice the source of most complaints – the unit either fails to hold temperature, switches at every little change, or cannot be set with sufficient precision.
Mechanical control (bimetallic thermostat)
An older and cheaper technology. A bimetallic strip bends when heated and interrupts the circuit. Disadvantages: inaccuracy of up to ±2–3 °C, hysteresis, mechanical wear, no possibility of programming. Suitable only for less demanding applications – occasional supplementary heating where precise temperature isn't critical. In practice we have seen bimetallic thermostats that drifted out of calibration over time, causing the unit to either not regulate at all or to switch on and off at a frequency that shortened the life of the heating element.
Electronic control (electronic thermostat)
The modern standard. An electronic sensor continuously measures temperature, with control accurate to ±0.5 °C or even better. The unit operates more smoothly, switches on and off less often, is quieter, and more economical. Most current mid- and higher-class convectors have an electronic thermostat with a temperature display and adjustable programme.
Programmable control and weekly schedules
The most comfortable form. You can set 22 °C on working days from 6:30 to 8:00, only 16 °C from 8:00 to 16:00 (setback while you're away), and 22 °C again from 16:00 to 22:00. A different programme for weekends. According to various measurements, such control can reduce consumption by 20–30% compared to a unit set to a constant temperature. If you're planning to use the convector as your primary heat source, investing in a programmable model pays off quickly.
WiFi and smart control
The most modern models offer control via smartphone, integration with assistants (Alexa, Google Home), and advanced consumption analysis. For ordinary use it's not essential, but if you're tech-savvy and want the comfort of remote control – for example, switching on the convector an hour before you get home – it's a nice bonus.
A detailed comparison of electronic and mechanical control can be found in the article Convector heater with electronic vs. mechanical control: which is better in our Knowledge Centre.
Other technical selection criteria
Heating element type: resistive wire vs. PTC
Classic convectors use a nichrome resistive wire wound on a ceramic core. PTC (Positive Temperature Coefficient) heaters are a newer technology – ceramic elements with a positive temperature coefficient of resistance, meaning that as temperature rises, their resistance increases and automatically limits output. PTC heaters are safer (lower risk of overheating), more durable, and generally more compact for the same output. Wire heaters still dominate the cheaper segment, while PTC is mostly found in premium models.
Dimensions and installation location
An electric convector heater is typically a low, long unit mounted below a window – the longer and lower the body, the better it covers the area in front of the window and prevents cold draughts that would otherwise flow down from the window across the floor. Typical dimensions: height 15–25 cm, length 40–100 cm, depth 8–15 cm. When choosing, always check whether the unit fits under your window, taking into account the window sill and any radiator shelf.
Some models are intended solely for wall mounting, while others can stand on the floor using a stand with castors. The Castor set for Tesy is an example of such an accessory – it allows the convector to be moved as needed. When a convector is wall-mounted and you later want to move it, for example to another room, castors are a practical solution without the need to drill again. The article Castors for an electric convector heater: when they're worth it and what to know discusses when it makes sense to use castors and what to know before buying.
IP rating and damp spaces
For bathrooms and other damp rooms, it is essential that the convector has appropriate protection against moisture – at least IP24 (protection against splashing water). Standard convectors without IP protection are intended only for dry spaces, and installing them in a bathroom is not only dangerous but also contrary to the ČSN/STN 33 2000-7-701 standard. In practice we have seen cases where a standard convector without IP protection ended up in a bathroom – the result was a short-circuited unit after a year of use and a costly repair. Only use models rated IP24 or higher in bathrooms.
Energy efficiency class
Since 2013, the European ecodesign directive has applied to electric heating appliances, and convectors must carry an energy label. Classes range from A+++ to G. Modern convectors with an electronic thermostat and programmable control achieve class A or A+. Pay attention to this label when buying – higher-class units cost more, but with long-term use they save enough on the electricity bill to make the higher purchase cost worthwhile.
Safety features
Every reputable manufacturer includes at least the following safety features in a convector:
- Thermal fuse – if airflow is blocked or another fault occurs, the unit switches off before it overheats.
- Tip-over protection – an important feature for models on castors: if the convector tips over, it switches off automatically.
- Control panel lock – useful when installed in a children's room, so children cannot change the settings.
- Open-window detection – some premium models detect a rapid drop in temperature (a sign of an open window) and automatically reduce output so as not to heat the outdoors.
Primary vs. supplementary heat source
You can use electric convector heaters in two basic ways: as the primary heat source for the entire apartment/house, or as a supplementary source to an existing system (central heating, heat pump, etc.). This decision fundamentally affects what output and control you need.
If the convector is the primary source, it must cover 100% of the room's heat load even during extreme frosts. Output must be sized for the worst conditions, not average ones. Control must be reliable and, if possible, programmable, since you're fully relying on it. In this case, expect electric heating costs to be higher than with a heat pump or gas – but zero installation and service requirements can be decisive in many situations (cottages, apartments without a gas connection).
If the convector is only a supplementary source – for example, heating a bathroom where the central system isn't enough, or tempering a room during the transitional season – the output doesn't need to be maximal, and a cheaper model with simpler control will fully suffice. A more detailed analysis of both scenarios can be found in the article Electric convector heater as a primary vs. supplementary heat source.
Protherm vs. Tesy: the two main brands on the market
The Slovak market for electric convector heaters is dominated by two brands – Protherm (a French-Slovak manufacturer) and Tesy (a Bulgarian manufacturer). Both have a solid reputation, but they differ in philosophy, construction, and price positioning. In short: Protherm appeals to customers who want simplicity, reliability, and pleasant design; Tesy offers a wider range, including premium models with WiFi control, and is more popular among customers looking for more technological features at a reasonable price.
A detailed comparison of both brands – differences in heater construction, type of control, available outputs, warranty terms – can be found in the article Electric convector heaters Protherm vs. Tesy: what's the difference and which to choose.
Installation: wall, floor, or a combination
You can install an electric convector heater fixed to the wall, where it hangs like a radiator, or place it on the floor on castors and move it as needed. Both approaches have their place.
Wall mounting is better in terms of aesthetics and function. The convector is stably positioned under the window, air circulates optimally, and the unit isn't overloaded. The electrical cable can be routed under the plaster or in a cable trunking. The disadvantage is that once mounted, it's hard to move. The step-by-step installation procedure – including distances from the floor, wall, and window sill – is described in the article Mounting an electric convector heater on the wall: step-by-step procedure.
Mobile installation on castors is suitable for rented apartments, cottages, seasonal spaces, or anywhere you don't want to drill. Just plug the unit into a socket. However, remember that in mobile use, the cable and plug must not be covered by a carpet or furniture – this is why proper cable placement is important.
Noise level and comfort of use
Another parameter that customers ask about less, but deal with more after purchase. A convector without a fan should be practically silent in operation – at best you'll hear only a faint crackling as the metal casing expands or contracts thermally when switching on and off. This crackling is physically unavoidable and is not a sign of a fault. However, if the convector makes loud humming, buzzing, or crackling sounds, it indicates a problem with the heating element, a loose cover, or loose mounting – in that case, read the article Common faults in electric convector heaters and how to fix them.
For use in a bedroom, we always recommend a model with an electronic thermostat – bimetallic thermostats have a characteristic click when switching that could wake a light sleeper in a quiet bedroom at 3 a.m.
Price, service life, and operating costs
Electric convector heaters are among the cheapest heating appliances in terms of purchase cost. A simple model with a mechanical thermostat costs from €40–60, a mid-range model with electronic control ranges from €80 to €150, and premium models with WiFi and advanced control cost €150–250. Installation costs are minimal – if no new electrical wiring is needed, you can do it yourself for the price of the mounting material.
With proper maintenance, a quality convector has a service life of 10–15 years. The main wearing parts are the heating element and thermostat. How to extend its lifespan and what to watch for when cleaning is described in the article Maintenance and cleaning of an electric convector heater: how to extend its service life.
Operating costs are directly proportional to electricity consumption. At rates of around €0.20–0.25/kWh and a 1500 W convector running 8 hours a day, that comes to €2.40–3.00 per day. Over a month (October–April is 7 months), that's €500–630 just for one convector as the primary source. This is why an energy-efficient system with programmable control and setback is key – a daily setback of 6 °C for 8 hours can realistically reduce consumption by 15–25%.
Most common selection mistakes – from our project experience
Over the years of practice, we have repeatedly seen these mistakes:
- Buying too weak a convector for corner rooms. A corner room may have up to two external walls and two windows – heat loss is significantly higher. A customer bought a 1000 W unit for a 15 m² corner space and was disappointed that it didn't reach 20 °C in January. 1500–2000 W would have been correct.
- Ignoring ceiling height. If your ceiling is 3 m instead of the standard 2.5 m, the room volume is 20% larger. The per-m² calculation needs to be adjusted.
- Installing a standard convector without IP protection in a bathroom. Safety risk, regulatory issue, shortened unit lifespan.
- Buying a convector on castors without professionally assessing the socket. Extension cords under carpets, weak sockets, or a shared circuit with other appliances – these are all potential sources of problems.
- Underestimating control. A customer saved €30 by buying a model with a mechanical thermostat and, after a year, dealt with either an overheated room or insufficient heating, because the bimetal was imprecise.
Frequently Asked Questions (FAQ)
How many square metres will a 1000 W convector heat?
It depends on the room's insulation. In a well-insulated apartment or new building, a 1000 W convector will cover an area of approximately 15–20 m². In an older, poorly insulated house with simple walls, only about 8–12 m². For corner rooms with multiple external walls, expect a lower value. It's safer to use a per-m² calculation than just rough tables.
Can I leave the convector on all night?
Yes, electric convector heaters are designed for continuous operation. They have thermal fuses and a thermostat that switches them off once the set temperature is reached. Letting them run in a night setback (set to 16–18 °C instead of 22 °C) is not only safe but also energy-efficient – the room doesn't cool down completely, and reheating in the morning is quicker and cheaper than if you turned the unit off entirely.
Do I need to connect an electric convector heater via a special socket or circuit breaker?
Models up to 2000 W can be plugged into a standard 230 V socket (a 10 A or 16 A circuit breaker is sufficient). For a fixed connection (without a plug), installation by an electrician is required. If you're installing several convectors in one room or house, consult an electrician to assess the total load on the electrical wiring – in apartments with original wiring from the 1980s, total capacity may be a limiting factor.
Which is better: a convector heater or an oil-filled radiator?
For continuous room heating, a convector is better – it heats the air faster, responds better to control, and is safer (the surface doesn't get as hot as with an oil-filled radiator). An oil-filled radiator is advantageous only in situations where you need heat inertia – the warm oil radiates heat for some time after switching off. For typical use in a living room or bedroom, an electronically controlled convector is more efficient and more comfortable.
Can I place the convector behind a curtain or furniture?
No. Covering the convector with a curtain, sofa, or other furniture blocks airflow, the unit overheats, the safety fuse activates, and the unit switches off. Repeated occurrences like this shorten the heater's service life. The convector needs at least 30 cm of free space above the outlet grille, and nothing should block the inlet grille at the bottom that would prevent air from entering. A curtain above the convector is acceptable only if it is short enough and doesn't cover either the inlet or outlet grille.
Is it worth buying a convector with WiFi if we'll only use it in the living room?
It depends on your lifestyle. If you come home irregularly and would like to switch on the heating on your way, WiFi control is worthwhile. If you have a fixed daily routine and a weekly programme set directly on the unit is enough for you, the WiFi function is a nice but unnecessary extra. Consider that WiFi convectors cost €40–80 more than a model without WiFi with the same output – this amount may not be recovered through energy savings, but it will save you time and minor inconveniences.
Conclusion: so how do you choose a convector heater?
Choosing an electric convector heater isn't complicated if you proceed step by step. First, determine the required output – calculate it from the room's area and insulation, not by guesswork. Then decide what kind of control suits you – for primary heating, invest in electronic and programmable control; for supplementary use, a simpler one will do. Check the IP rating (bathroom = IP24+), verify the dimensions and installation location, and don't forget the safety features. Finally, compare specific models – the range of electric convector heaters at atria.sk covers the entire output range from 500 W to 2000 W, with various types of control and design, so you'll find the right model for your situation here.
If you're not sure which model to choose, read more articles in our Knowledge Centre – especially Frequently asked questions about electric convector heaters, where you'll find answers to situations we haven't had space to cover in depth here.
Do you have a question on this topic?
Can't decide, or dealing with a specific situation in your household? Write to us - we'll be happy to help.