In the UK (and I guess US and EU) there are numerous adverts now claiming super efficient electric heaters that can warm up a room in minutes and costs pennies to run have been developed by some engineer or student. due to cost of heating.  I notice in UK most of these devices are around 800 watts.

I am no electrician but 800 watts cannot heat anything efficiently, 1kW struggles, 2kW may be minimum required to create much heat so I do not believe any of these adverts.

I know in US as your voltage is half of UK your normal devices that plug in to the wall are half of the usual wattages of UK devices so, in some of the colder States, wonder what portable type electric heaters are used.

Geffers

Web Diva said:

I talked to an expert, let's see if I can recall the information correctly.  If a 800 watt heater is using a 120 volt outlet, it would make about 2000 BTU's.  You can compare that to a 36000 BTU air conditioning unit at 3 tons.  I may have some of this a bit wrong, but, to your question about can these heaters heat up a room than by the above conversions, that confirms your suspicions on adverts, that those heaters can't heat up a room.

Also to consider the error of using square foot per room rather then cubic square feet in advertising a product.  Cubic square feet is a better measurement and a lot of these products advertise with square foot.

Indeed, cubic measurement better than square, some rooms do have high ceilings. 

Geffers

Ok, I am no expert on BTU's, however, let's talk about voltage first! It doesn't matter what voltage we are talking about whether it be 240v (UK), 120v (US) or even 12v as the equation "volts x amps = watts", it's the wattage that is important as this is the final output power of an electrical device, whether it be a heater, motor, oven or indeed a microwave oven (I think we are all familiar with our microwave oven wattage?). 😃

Secondly, yes @Web Diva, you are completely right about the cubic measurement! My lounge is 12' x 12' x 8' high, that's 1152 cubic feet. If they are advertising 800 watt heaters for a given floor area in square feet, maybe that's an advertising cop out for them as 800 watts will hardly do anything in my lounge especially with the cold hard frosts we have recently had, it might if we were all midgets and only had a ceiling height of about 1 or 2 foot! The lady I do the gardening for actually has an 800 watt heater in her greenhouse, but that is purely to protect it from frost, it certainly won't heat the greenhouse up! 😑

I have gas central heating but I do have a 3kw convector heater as a back up in case the heating goes down, but even that in my lounge hardly makes a difference!

So in my opinion I will certainly not be investing in one of those advertised heaters! 😎

Mark Ransome said: or indeed a microwave oven (I think we are all familiar with our microwave oven wattage?).

I have gas central heating but I do have a 3kw convector heater as a back up in case the heating goes down, but even that in my lounge hardly makes a difference!

So in my opinion I will certainly not be investing in one of those advertised heaters! 😎

Microwaves, in UK the wattage are quite odd, 700 or 800 watts although mine is 1kw but also has power levels.

Am surprised your 3kw doesn't heat up your lounge,  my central heating is gas and heat via water filled radiators, takes time to heat up, I generally use electric blow heaters to initially warm or give a boost.  Blow heaters very simple, 1kw or 2kw, find the lower setting fine for assisting the radiators.

Guessing your 3kw uses a double feed otherwise at 110v amperage too high.

Geffers

My 3kw heater is only a convector heater (No fan) so is slow to take effect, and my voltage here (UK) is 240v. 😄

Mark Ransome said:

My 3kw heater is only a convector heater (No fan) so is slow to take effect, and my voltage here (UK) is 240v. 😄 

Ah, OK, I mistakenly thought you were US.

I've often wondered about fan assisted, they can of course direct heat better but thinking they cannot overall be more efficient, if 3kw comes out of element that is all that can actually be used.

You've no doubt seen the adverts too suggesting a couple of tea light candles in a flowerpot can heat your home 😂 😎

Geffers

Fan heaters can have a faster effect but I don't want the noise they make, as for the candles, no I have not seen that one lol! 😂

Mark Ransome said:

Fan heaters can have a faster effect but I don't want the noise they make, as for the candles, no I have not seen that one lol! 😂

Here is a quite elaborate version but have seen one with just one candle.

 https://youtu.be/GV23gAO7F8E?si=kfzyxv4ZJUPbknQw

Geffers