Electricity price - do dimmers save money?

[msmx5s]

Hi all,

Hope you can help.... Sorry if it's been asked before... I'm new.

I have an uplighter with an R7S 300W halogen bulb. In these times of rediculous prices for electricity, does the dimmer on it save money or not?

I've been living in relative darkness for months!

Cheers in anticipation.

 

[jason1958]

Heh heh

Halogen/Incandescent are a peculiar animal.
- 300W input = 100% illumination output
- 200W input = 30% illumination output, rest is still lots of heat

Can not recall the exact figures, but it is a horribly logarithmic relationship.
- Drop the voltage a little, and you lose a lot of illumination
- So dimming halogen/incandescent will simply not achieve much

Basically lumens will fall faster than thermal dissipation

The "solution" is fluorescent lighting.
- You can get 35W or bigger BC/ES bulbs
- Colour temperature from "green" to "daylight"

Daylight are sold under "SAD" re winter light susceptibility on Ebay cheaply, however the light is very different from yellow incandescent or normal fluorescent, some people like it and some people dislike it.

You probably want "soft-tone", which will mean several bulbs.
You can get reasonable light output from 3-4x 16W Philips soft-tone fluorescent which give a good approximation (yellow) of incandescent. Then supplement with a 20-25-35W bulb as necessary.

You will save 0.22kW * hrs-a-day * days * £0.11 on electricity per year.
- For an average of 5hrs a day that is £44/yr
- Same as a PC or fridge

 

[Richard C]

The answer is not that you'd notice it much; might as well run it at full whack & enjoy.

 

[msmx5s]

Thanks Guys.

I do like to be able to dim my light though for effect rather than money saving. Am I right in thinking that you cannot dim fluorescent bulbs?

 

[johnnykc]

You CAN dim CFL's ..........Varilight have developed a dimmable CFL in either ES or BC and unlike other 'dimmable' CFL offerings it dims like an incandescent lamp i.e. large dimming range and subtle change of colour (temperature) ....each one of those will save you over £100 in energy over the lifetime of the lamp .....you can get them at TLC

 

[sparktacus]

If you are that worried about your electricity costs you should bin this lap and get yourself a few cheapo lamps from Ikea using different sized low energy flourescent lightbulbs. That way you can have different levels of light and save on your bills at the same time, without having to muck about with dimmer switches.

 

[ban-all-sheds]

Several lights in place of a fewer number means adding new cabling and switches.

This needs to be done safely, so testing is involved.

How is this going to be cheaper than fitting dimmer switches?

Particularly if the new cabling and switches becomes notifiable....

 

[breezer]

you could always have one of these and one of these

That way you do not have to worry about part P, and you can have differnt levels of light

 

[gman76]

Okay, I'm probably being thick here, but I have one of these 300w dimmable uplighters.

When it is run at maximum setting there is a tremendous amount of heat & light emanating from the lamp.

However, when it is run at, say, 30%, there is substantially less heat & light emanating from the lamp, also the dimmer runs merely warm.

Where does the other energy go?!

Apologies for overlooking the obvious, but it must use a bit less no?

 

[msmx5s]

Thanks everyone. I think I'll just buy a new uplighter so I can install a fluorescent energy saver bulb. I don't need so much light. I'd be able to see the misses across the room. Don't want that...

I just thought it was a bit excessive having a 300W bulb burning away, and thought I was saving energy turning it down. Guess I was wrong. I also think I'm going to win the lottery every week, but I'm always wrong there too.

breezer - I wondered WTF you was on about when I saw that shelving unit. I've only just got it after reading it for the 5th time. lol

 

[gman76]

Ok, I've got a question for RF Lighting;

On a similar subject to this thread - I've seen a couple of post replies (one of which to mine), which intrigue me slightly.

You suggest that, putting a dimmer or similar on a heated towel rail or tube heater, will only delay the time the item would normally reach it's maximum temperature.

How is this possible, if a simple lamp will never reach maximum working temperature if used on a dimmer set at a lower level than maximum?

Maybe I'm just an idiot (as my GF keeps telling me) or I'm missing something?

 

[sm1thson]

Okay, I'm probably being thick here, but I have one of these 300w dimmable uplighters.

When it is run at maximum setting there is a tremendous amount of heat & light emanating from the lamp.

However, when it is run at, say, 30%, there is substantially less heat & light emanating from the lamp, also the dimmer runs merely warm.

Where does the other energy go?!

Apologies for overlooking the obvious, but it must use a bit less no?

It will use less, but not proportionally. Incandescent lights are more efficient the more current they have, this is most noticeable when they are run at/near/over their maximum. So if you reduce the current a bit you loose a lot of light. So for example (made up numbers) if you give the light 80% max current and in return you get 30% max light you can see it is a false economy using the dimmer one or two lower rated incandescent would give more light for less power. Naturally used CFL’s is the way to get the efficiency as the op has seen.

 

[ban-all-sheds]

Where does the other energy go?!

It doesn't "go" anywhere - basically the dimmer is a rapid-fire switch, it turns the lamp on and off 100 times a second, the shorter the "on" the dimmer the lamp - it's not soaking up what the lamp doesn't get.

 

[breezer]

breezer - I wondered WTF you was on about when I saw that shelving unit. I've only just got it after reading it for the 5th time. lol

I expect the others will cotton on to it in a while, some times my humour is a bit ................

(or then again, perhaps you are the only other one who understood the joke)

Where does the other energy go?!

Origiinal stage lighting dimmers did used to have giant coils, they had a "wiper" depending on where the wiper is depends how bright / dim the light is.

if the wiper was at the bright end the coil would be room temp. if it was at the dim end the coil would offer a lot of resistance and the coill would actually heat up (thats what they were meant to do) so the lecy the lamp wasnt using was dissipated as heat

this "principal" is still used today, its called a toaster.

look inside a toaster, you will see a wire running back and forth, forth and back.

this wire gets red hot, which is how it heats the bread to make your toast.