Expert: cleggsan - 1/1/2007

Question
Thanks for the answer.Thanks to you, I now know for sure that electrical heaters use up more electricity than other electrical appliances such as video players,lights,etc. However, I am still in the dark as to whether,for example, a fan heater uses up more electricity than a convector one or a halogen one uses up more than a convector one.
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Thank you for the answer.I think I understand most of what it contained. However,concerning the area of which type of heater consumes the most electricity, I would like more explanation. First I will share some observations. The place  I live in has a money-fed electricity meter. I have noticed that the coins I put in require topping-up more regularly when I use a fan heater as opposed to in the summer when I use only lights,tv,hi fi,toaster,etc.This would suggest that  the fan heater uses up more electricity than other appliances. I was rather hoping that another type of electrical heater would use up less electricity thereby saving me some money on electricity expenditure,but it seems from your explanation,this is not the case.
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I would like to know in just a little detail what the differences are between fan,convector and halogen heaters. I would also like to know which of these 3 types of heaters consume the least electricity.
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Well, last question first:  Heat is heat and power is power.  Electrical power is in watts. It is determined totally by the voltage and the current passing through the resistive elements.  Watts = Voltage X Current.  When a heater is rated at 1500 watts, for example, it means the resistive heating elements will produce 1500 watts of heat.  The method of getting the heat out from the heating elements into the air is the other factor.  A fan, for example, will push the air out more quickly, perhaps, and spread it round more evenly into the room, but the amount of heat is still 1500 watts and the fan will not increase the amount into the  room; it will only distribute the heat more efficiently, perhaps.  Convection merely means the heat will travel due to the "heat rises" concept and will heat the spot near the heater quickly and the room less quickly, but in the long run it will still be the exact same amount of heat.

Halogen heaters are just another way of heating the air; the amount of heat is still the same, the heating element may be a different material and it may have different radiating qualities, but the amount of heat for a 1500 watt device will still be 1500 watts.  Actually, the wirewound heating elements that glow when turned on, whether there is a fan or not, are the most durable and will outlast all the other types.  The oilfilled radiator types are heated with a resistive wire and have long life, also; they distribute the heat  with rising air circulating around the radiator, but as the others, in the long run, it is still a 1500 watt heater.  Whatever the heater wattage rating is; that is how much electric power they consume - period.  (Note: Lots of market hype in this area wanting you to believe that certain materials or configurations will magically produce more heat or thermal energy for a given input, but they can't and don't).

cleggsan

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Electric heaters DO use more power (watts) than most appliances because they are steadily consuming when the heater element is ON.  And, many of them are designed to run the current right up to the level where most homes have the breakers set to dump out.  So, it is going to be expensive no matter what you do.  If the fan type heater uses more electricity it is probably because the element is staying on longer due to the fan blowing out the heat more quickly and distributing the heat away from the heater unit and keeping the thermostat just a little cooler on average - but the room may be just a little warmer due to the heater staying on a little longer than when compared with the non-fan style heater......  There are many variables.

Cleggsan  

Answer
It depends on the ratings and the thermostatic sensitivity and the size of the room.

IF:  Any two heaters are left ON 100% of the time and have the exact same power rating they will, by definition, consume the exact same amount of electric power and will, by definition, put out the same amount of BTU heating.

HOWEVER:  In a typical situation the distribution of the hot air around the heater will warm up the thermostat and cut the heating element off for a period of time until the air temperature drops to the point the thermostat of the heater kicks it ON again.  The size of the room, the design of the thermostat and the convection of the air are the main factors that will effect the air temperature changes around the thermostat.

THEREFORE:  One type of heater may be kicking off and on in a different cycle than another heater due to these air circulation differences.  Also, the design of the thermostat in the heater and its position for sensing the changing temperature will effect its ON/OFF cycling.

CONCLUSION:  The difference in power consumption will be due to the ON/OFF cycle or duty cycle imposed by the external factors controlling the air flow and the thermostat design - and of course the temperature setting the user decides for comfort.  But, while the unit is ON all heaters of the same rating will consume the same electric power from the mains.

Cleggsan
PS: Beware of marketing hype claims; however, there are some heaters that rely more on radiated heat transfer than on convection heat into the air; this is more a personal choice, but the BTU heating is the same; just injected into the room in a different method.