# How could I make a 1kW fan heater consume less electricity? [closed]

My fan heater has only two settings, 1kW and 2kW. But what if I wanted it to consume only 200W per hour ? Could I find a device to put in between to supply less electricity, how would I do that?

## closed as off-topic by Voltage Spike, Daniel Grillo, Autistic, Scott Seidman, brhansOct 26 '16 at 20:59

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• You buy a 200W heater. – Marko Buršič Oct 19 '16 at 7:47
• There is no such thing as "200 W per hour". You want 200 W. If you use a dimmer which can handle the motor load of your fan inside it and dim it to 20% or 200 W, you might end up in a situation where the fan stops running but your heating element still gives off heat, although much less than before. – winny Oct 19 '16 at 7:47
• Switch it on for 1/5th of the time. Possibly with a timer (contact making clock). – polwel Oct 19 '16 at 7:48
• Run it at 2000W for 1 minute, then turn it off for 10 minutes. The average power will be 200W. – JRE Oct 19 '16 at 7:49
• "200 W per hour" means nothing, you mean you want it to consume 200 W instead of 1 kW or 2 kW so that it consumes not 1 kWHr or 2 kWHr but 200 WattHour. What you do is duty cycle it on 1 kW setting: 1 minute on, 4 minutes off giving 1/5 of average power = 1 kW /5 = 200 W. – Bimpelrekkie Oct 19 '16 at 7:50

As has been covered in the other answers, you have your units confused. If you want to reduce the heat output from your heater to an average of 200 W, you need to pulse-width modulate the standard 1000 W output setting. To do this, you need a time-switch. On for 20 minutes, off for 80 - repeat. Finding a time-switch that allows you to set enough on-off times at the right precision might be hard - a temperature based approach might be simpler.

This will not reduce the peak power draw, or how hot the heater might get (to a first approximation). Switching like this will increase the chance that the heater fails sooner, maybe not by very much.

There is an error in what you said: the fan heater power is either 1 kW or 2 kW, but when you say that you want it to consume only 200 W per hour you're talking about energy, which is just $power \times time$. Thus, your fan heater consumes either 1 kWh or 2 kWh, depending on the setting, (as pointed out by user FakeMoustache in the comments) and you would like it to have a 200 W power (thus reducing its energy consumption and the heat it gives you).

Then, anyway, the answer to your question is no, you can't put anything in between, if by "in between" you mean between the mains plug and your device. What you would have to do is to open your fan heater and modify its internal circuitry, those modifications depending on the fan heater you have.

Yes, you go to hardware store, electrical department, and buy a 1200W dimmer.

REWORK SUGGESTION: you will need to open up the AC cord, identify hot wire, and install (wire-up) the dimmer in accord with dimmer instructions. Then wrap the whole thing up by duct tape, in best DIY traditions. Do not use 2kW configuration.

• this will run the fan slow as well, which may be too slow, as in stalled. – Neil_UK Oct 19 '16 at 8:06
• Also, it's a 2000W heater, so the 1200W dimmer will fail. – Steve G Oct 19 '16 at 9:41
• Non-issue, folks. The device has a 1kW configuration, I assume it is not by active dimmer. To drop 1000W to 200W, the voltage needs to be only at about half level, so the fan will likely be fine. If not, connect the fan directly to AC, and use the dimmer on heater only. – Ale..chenski Oct 19 '16 at 16:03