Room Heating Guide

It is imperative to get the right size radiator for the room or area you are trying to heat. If you fit a radiator that is too small, it will be working too hard and be on all the time. This will directly affect your running costs. If in any doubt, please choose the next radiator up in size. It is never a bad decision to over-specify in order to get optimum performance.


What Size Do I Need?

To find out what size radiators you require simply visit the product pages on our online shop and select a size from the dropdown. You will then see details of the size room the radiator can accomodate along with the dimensions and weight. Alternatively, please contact us and we will be happy to assist

The guide is based on length x width of the room, with a ‘normal’ height ceiling (2.4m) and based on one outside (external) wall.  

Factors to Consider:

  • Level of insulation – Modern Insulation, Poor Insulation, Loft Insulation, Cavity Wall Insulation.
  • Age of the house.
  • Geographic location – If you live in the Scottish Highlands you will need more power than if you live on the south coast of England.
  • Number of outside (external) walls.
  • Ceiling Heights.
  • Aspect of the room (e.g. North/South facing).
  • Concrete floors.

Modern Insulation

Modern insulation is when you have cavity wall which is well insulated, double glazing and insulated loft to the latest standards. Nearly all property built after 1996 are likely to be well insulated. As a guide we use a wattage calculation which is based on 85 watts per sq/m. If you do not meet these requirements use the poor insulation calculation. 

Poor Insulation

Poor insulation is mainly confined to older properties which have no cavity wall or insulation and lots of single glazed windows which allows more heat loss. Because of the larger scope for heat loss as a guide you need to allow higher wattage calculation which is based on 100 watts per sq/m. 

If you miss an area, have the door open to other areas or have an open staircase please take this into account.

REMEMBER – It is NEVER a bad decision to over-specify. You don’t want a cold room, you want to get the best performance from your electric radiator in order to generate the best energy efficiency and comfort. 


What If My Room Is Between Two Sizes?

Always go for the higher wattage when the size of the room falls between two radiators sizes. As mentioned before it is never a bad decision to over-specify. A larger radiator will heat the room faster and switch off quicker, working well within itself. A smaller radiator may be working too hard all the time to achieve the desired temperature.


Larger Rooms

If your room size is too large for one radiator, simply add another radiator to get to the required wattage. e.g. If your room is 5m x 5m = 25 sq/m, you can use 2 x 1250w or 1 x 1500w + 1 x 1000w.


Do I Need A Smaller Radiator For My Bedroom?

No. The room size always dictates the size required. REMEMBER, you are in control of the temperature. Sleeping can be uncomfortable if the temperature is too high. You can set the temperature to whatever you like, lower during the night and higher for when you are getting out of bed. Also our window open detection sensor will stop energy being wasted when detecting a sudden drop of temperature.


Ceiling Height

Our room size guide is in m2 and assumes a ‘normal’ ceiling height of 2.4m. A ceiling height of over 3 meters will need extra wattage.


Conservatories and Orangeries 

Conservatories and similar rooms will require higher wattage as there is greater heat loss. Please contact us for advice.



Our radiators are IPX4 rated and should be professionally installed in bathrooms zones 3 via a fused spur.  Please check with an approved electrician for which radiator is most appropriate for your property before purchasing as you need to comply with current regulations.


How to position a radiator

Always try to install the radiator onto an external wall under a window.  Never fit in a ventilated area or in direct sunlight to prevent the thermostat from functioning ineffectively. The minimum distances between the radiator and the ground or wall is 150mm. 

Avoid placing the radiators behind furniture which would lead to the blocking of radiated heat from our solid aluminium body and not allowing for convected air to circulate.  Do not cover the radiator as this would prevent it from heating properly.   

We recommend leaving the radiator on all the time, running a programme between two temperatures.  A comfort temperature for when you are using the room (perhaps mornings and evenings) and an economy (set back) temperature for when you are not using the room (for example at night or when you are out at work). The economy temperature should be 3 or 4 degrees lower than the comfort temperature.  Generally, a comfort temperature should be between 18 and 21 degrees. Example: If the comfort is 19 degrees, the economy temperature should be 15 degrees. Switching on and off and heating a room from cold will use more power than if used as above.

With iVista models of Curvo+ and Prisma+ the iVista mobile technology and management allows you to control the temperature from anywhere using the easy to use app allowing for greater saving in energy usage.

The temperature control is in your hands, the higher you have the thermostat the more it will cost to run, if you turn it down you spend less. Turning the heating down 1 degree will save between 7 – 10%.

Also if you have not already done so, please shop around for the cheapest energy supplier, we actively help customers find the best tariff.  

Talk to us today on 01845 595945.