Convector heater running cost

To work out the cost of running your convector heater, you first need to find out the following information

1) The electricity consumption of your Convector Heater
2) Your current Electricity cost for each unit of Electricity you use

Convector heaters often have labels or metal stamped plates attached to them, which show their Electricity Consumption, usually these can be found on the back or underside of the Convector Heater. When you read the label, you will often see something which looks like

Volts:- 230v, 50hz, Watts:- 2000

The information which you need to be able to work out the cost of running your convector heater is shown by the number of Watts. Sometimes this may also be printed on the label as a single ‘W’ – i.e 2000W or expressed in Kilowatts (KW). Basically a ‘KW’ (Kilo-watt) equals 1000 watts of Electricity, and so 2000 Watts would be 2KW and 3000 Watts would be 3kw and so on.

Next you need to find out how much you pay for each unit of Electricity that you use. As of Oct 2023 Electricity prices in the UK are at record levels and are generally in the region of 30p per kw/h. This varies slightly from Electricity provider and region, and may be lower if you are on a legacy fixed tariff so the easiest way to find out what you pay for a unit of Electricity would be to check an old electricity bill, the cost will be shown as kwh – for example 30p / Kwh – this means that you pay 30 pence for each unit of Electricity consumption that your meter records.

The example above uses UK Sterling for the Electricity cost, but this can easily be substituted with other currencies, such as U.S Cents as the calculation method is exactly the same.

One unit of Electricity is consumed for every 1000 watts of consumption recorded by the Electricity meter  over a period of 1 hour. So to run a 1000 watt heater continuously for 1 hour would use exactly 1 unit of electricity, and at a cost of 30p per unit (KWH), a 1000 watt convector heater would cost 30p per hour to run.

So a 2000 Watt Convector heater would use 2 units of Electricity for every hour that it is run, and at 30p per Electricity unit it would cost 2x 30p = 60p per hour to run

A 3000 Watt Convector heater would use 3 units of Electricity for every hour it is running, and so would cost 3x 30p = £0.90p per hour to run.

Remember that 1000 watts can also be expressed as 1kw and 2000 watts = 2kw and 3000 watts = 3kw. Fractions of this can also be represented by using a decimal place, and so a 2500 watt convector heater may also be referred to as using 2.5kw, a 2400 watt heater as 2.4kw etc.

You can also work out the cost of running a convector heater by using the KW rating directly and a simple maths equation.

So we already know that a 2000 watt heater can also be expressed as 2kw

so we use the following basic maths equation to work out the running cost of an appliance for any period of time

Running cost = Consumption of Heater in watts X number of hours run X Electricity Unit Cost

So lets work out how much it will cost to run a 2000 watt (2kw) convector heater for a period of 5 hours where each unit of electricity costs us 30 pence

2 (kw) x  5 (hours)  x 30  (pence) =  300 pence or £3.00

So to run a 2kw convector for 5 hours would cost you £3.00 in energy based on an Electricity unit cost of 30 pence

Lets do the formula again, but this time using the rating of a 2500 watt convector heater, and an Electricity unit cost of 30p  in the example.

2.5 (kw) x 5 (hours) x 30 (pence) =  375  Pence or £3.75

So in our second example, to run a 2.5kw convector heater for a period of 5 hours at an electricity cost of 30 pence per unit would cost just over £3.75 in Electricity.

Remember that these are worst case  figures that are based on the Convector Heater drawing Electricity continuously for the entire running period. However  if you have a convector heater which has a built in thermostat (recommended), this will switch off the convector heater automatically, when the room has heated to the temperature selected on the Thermostat. Once this happens the heater will turn off again, until the room cools down by a couple of degrees, at which point it will switch on again to replace the heat lost, and will continuously do so, until it is either switched off, or the thermostat is adjusted.

This cycling of the heater, means that once the room has warmed up to the desired temperature, the heater stops consuming Electricity and so saves money. How often the heater switches off, depends on a number of factors such as the outside temperature, the size of the room, how well insulated the room / building is and of course how high the thermostat is set. The more heat that is lost through the fabric of the building the more heat the convector heater will have to produce to replace it and the ‘on’ periods will be far longer, and the running costs, much higher.

In a well insulated room, and using a convector heater with a built in thermostat, you could reasonably deduct  15% – 20% from any cost figures that you have worked out in the maths formula above to allow diversity for the heater switching on and off. However in a poorly insulated building this saving may only be 5%, assuming it reaches the desired temperature on the thermostat at all.

As you can see Convector Heaters, Electric Fires and Fan Heaters can be extremely costly to run and as of 2023 Electricity is the most expensive form of heating, more so if the room or property you are heating is poorly insulated. If you are intending to stay in the property for a long time, then consider installing Storage Heaters which use cheaper off peak Electricity for your room heating.

You may also want to consider using  Halogen Heaters instead, as they are designed to heat people rather than attempt to heat the entire airspace of the actual room. So its possible to feel comfortably warm from using a lower wattage of heater. The only drawback of this is that the heaters have to be pointed at you to feel warm, but that is a small price to pay for what might be a 50% or greater saving in daily running cost (1.2kw halogen heater vs 2400 w convector)

It is also very important that you work out just how much heat is required to warm the size of room to a comfortable temperature. For example, if a room requires 4kw of heat input to warm it to 21c, then you are unlikely to be able to heat it adequately by using a single 2kw or 3kw convector heater. To produce the 4kw required to heat the room comfortably, you would be advised to use (2x) 2kw convector heaters which would work out very expensive. (This calculation doesn’t apply to Halogen Heaters as they are not warming the entire room).

You can easily work out how much heat is required to warm a room of a given size, by using a room size heat calculator. Simply enter in the room dimensions, and the heat calculator will tell you the minimum amount of heat required to do it.

It is false economy to try and save money by using a smaller heater than the room size calculator advises. By trying to heat a room whose size requires 4kw of heat by using a 2kw convector will result in the room constantly feeling cold, taking many hours to reach a comfortable temperature and mean that the room probably never gets warm enough to switch off the thermostat, so the heater uses power continuously. In this situation you would be much better off using Halogen Heaters for personal comfort.

Another option to Electric Heating, which you may also like to consider are Japanese Inverter Heaters and these typically cost upto 70% less to run than an equivalent sized Electric Convector Heater.