Electric heater efficiency

Well, if the energy doesn't come out of them as heat, where does it go?

That's what I thought. But you know when people are so convinced it gets you doubting...

Climate change is based on that principle.

It's the old convection, conduction, radiation thing, isn't it? All the energy escapes from the device but how much is convected into warming up the air, how much is directly radiated towards objects and how much conducted elsewhere makes some types of heater more suitable in certain sorts of circumstances. Remember, before central heating was popular, the heat/light units in bathrooms? Oh: that's only me then....

Nick

Depends on what you mean by efficiency. If the technical term, most are anything but s**te - as near 100% as makes no difference. Far better than any gas fire or whatever. Except that electricity costs more.

But as regards how well they heat the person rather than room, a radiant type might be better under some circumstances.

NT

On Thursday, January 5, 2017 at 12:22:15 AM UTC, Nick Odell wrote: . Remember, before central heating was popular,

Horrible, weren't they - you could feel your scalp roasting while your toes (other appendages, too, if you were unlucky!) were being frozen off... There are still a few places that use these - mainly I suspect in places where heating is only occasionally required.

Well, on the grounds you get most of the energy out in the form you want (heat) then that makes them pretty efficient from a numbers POV. How good any particular design is at heating a particular space is another matter.

Generally, yup.

It all depends what he was really getting at. For keeping *you* warm in a cold workshop then any convection heating might not be considered as good as a radiant or fan heater for putting the heat when it can be best used (eg, at / on you).

If you want safe and silent (electric) heating in say a bedroom then a oil filled radiator might be the best thing. Because panel heaters often have an open element that gets quite hot then you tend to get more expansion clicks and clonks than say an oil filled rad.

That said, I recently bought a small (450W) oil filled rad for some background heating and I'm not sure if it's working properly (as in the ideal design solution). It seems, even at 450W, it can't liberate it's heat fast enough (even with the adjustable thermostat at the lower settings) and so sits there cycling on the overtemp stat which is too noisy (and frequent) for a bedroom, till it gets up to the temperature for the main stat. ;-(

I'm working on an external solution with an Arduino, a solid state relay and a couple of digital thermal probes. One probe will be clipped to the rad to ensure it doesn't get to the switching point of the overtemp stat and another to be the room stat that can be remote from the rad itself.

Cheers, T i m

All electric heaters are 100% efficient. Heat is the only output. Exce= pt for heat pumps (air conditioning run backwards). You can get 400% th= ere, as you suck heat from outside.

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Does the Little Mermaid wear an algebra?

Fact: all electric heaters of the household type (ie heater is sitting insider the house) are 100% efficient.

However, cheap convector heaters lack the surface area to run at full power all the time and end up cycling on the thermostat. A good oil filled radiator (eg deLonghi Vento that I have) can run for a 100% duty cycle.

A cheap B&Q one I had could manager about 50%

That is not efficiency, but maybe it's what he meant?

IIRC there was also an issue with lamp bulbs only intended for use in dry locations being fitted, and shattering as a consequence.

Chris

At one level that is true. Unless you use a heat pump.

But there is a big difference in how that heat gets distributed and how it makes the room feel. Convector heaters do a great job of creating a thin layer of very hot air against the ceiling for the benefit of any bats roosting up there. You will only feel a benefit when the hot air eventually fills the room down to the height where you are sitting.

You need something with a fan in it to stir the air up a bit and warm the air in the room up quickly. The difference is substantial in terms of comfort level since the air in a room doesn't take all that much energy to heat it up and mainly determines how it feels to you.

The walls and ceiling will remain cold for longer but how often do you touch them?

Of course if your mate has just spent thousands of pounds on magic German c lay-filled heaters he must believe they are better than a £10 Argos he ater.

Owain

It travels along the mounting screws and gets lost in the wall?

Maybe the word is efficacy?

Isn't that equally true of conventional water-flow radiators?

I have an expensive Dimplex fan heater with a similar problem, the thermostat senses the heater output airstream not the room temperature.

Owain

In workshops and other large industrial spaces it is not uncommon to mount radiant heaters 8 to 10 feet up, directed at the working region. In terms of watts per cubic metre, these are very good at improving the comfort level, particularly for people who are moving around a bit, even if the air temperature is not raised to "domestic" comfort levels.

At home, though, you can't beat a thermostatically controlled fan heater at floor level. You also need to control cold draughts (for comfort).