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10 100 watt bulb verses 1000 watt heater?

14 years ago

Will 10 100 watt bulbs put out the same amount of heat as a 1000 watt space heater?

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Comments (12)

classicdave
14 years ago
ohms law
watts are watts and the electric company charges by kilowatts
so that 1000 watts by lightbulbs or a 1000 watt heater probably costs 13 cents an hour depending how much your utility company charges per kilowatt plus tax.
baymee
14 years ago
Added benefit: You make light while heating the house.
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I think you can use any type of light that you like, but there are provisos! Fluorescents (modern triphosphor tubes on a high frequency electronic ballast) and metal halide lights are more or less equal in efficiency today. HPS is still more efficient and you might want to choose that if you are just supplementing good natural light. Metal halide bulbs are a simple way to get 400W-1000W of light, but need to be replaced after a year or so of continuous use and can have problems with burning plants that get too close. The described fluorescents should last for about five years, you will need a lot of tubes to provide high light levels, and it can be difficult to fit in enough tubes to provide very high light intensity. For the plants you are describing, you will probably need something like 40W of light for every square foot you wish to illuminate, maybe a little less if you are still getting good light from a window. It can be a challenge to fit enough fluorescent tubes in, you would probably need to use thin T5 tubes. Imagine maybe 10 or 15 of those and it will work just as well as a metal halide, probably better. If you decide to use fluorescents to achieve high intensity light, you may want to consider placing some of the tubes behind and at the side of the plants, not just above. Whichever way you choose, make serious efforts to get all your light onto your plants. Use good reflectors or enclose the whole area with something bright white or reflective. When you are considering maybe 400W of light running half of every day, it is far more cost-effective to capture all the light than to lose half of it and have to run a 1000W bulb instead!
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Kevin, For a very small area like 2'x1', even 150W is really too much. A quick rule of thumb is that 20W per square foot is enough for most growing needs. Often you can use less than that, maybe a bit more for real high light situations. So for that small area, what you really need is a compact 40W light source and a reflector to make sure that you are only lighting that area and not the whole room. Metal halides are too powerful and fluorescents are too long, although you could use some 24" fluorescents if you don't mind the cost and low efficiency. I would recommend a compact fluorescent bulb and a reflector, you can get 42W bulbs quite easily, or maybe a bit more if you want high light. I'm not a herb grower, can't tell you exactly how much you need. On spectrum, the bulk of the light for any type of growing should be red, in the 600nm-700nm range. These photons take the least watts to produce and they are used efficiently by the plant. Blue photons can also be used but it takes more energy to produce each one. In practive you need about 10% of the photons to be blue because they cause the plant cells and leaves to orient properly towards the light and power some internal processes. This is equivalent to about 25% of the energy going into blue light. The physiological balances between plant elongation, branching, and flowering are controlled far more by the relative amounts of red and far red light than by the proportion of blue light. So it simply isn't true to say that blue light causes growth and red light causes flowering, this is a vast approximation that kind of defines the effects of HPS and metal halide lights. By an odd coincidence (or simply because somebody found out it works), the old cool white and warm white fluorescent combo puts about 75% of the energy into red light and 25% into blue light (ignoring the green bits!) and so do the pinky-purple grow light fluorescents in one tube. Metal halides produce more blue and HPS produces more red. HPS simply produces more photons per watt than other light sources and usually wins out, but the colour distribution can cause plants to elongate rather than grow compact and strong. The light distribution may also encourage plants to flower rather than continuing to grow, but if this can be avoided they will grow just as efficiently as metal halides. Commercial growers of most crops use HPS with blue supplemental lighting (or some natural lighting which includes blue photons) rather than taking the efficiency hit of going to metal halides. Take the hint from these guys because they have to provide quality, but it is their own money at stake. Metal halide bulbs (and HPS and, to a lesser extent, fluorescents) decrease in brightness over their lifetime. The decrease is not readily apparent to the naked eye unless you compare a new and old bulb side by side but it might be as much as 40% less photons at the rated lifetime. In addition, metal halide lamps have a habit of failing catastrophically if you run them right to failure. There are protective envelopes to minimise damage but failed bulbs can emit dangerous UV and be a fire hazard. Newer bulbs are less likely to explode, but metal halides are typically swapped out on a timetable rather than when they fail. Growers often swap them out at 6,000-8,000 hours to maintain maximum light intensity and efficiency. This might seem excessive and costly, but remember than the bulk of the cost of running any light source is the electricity. It is worth considering that even though you might get a freebie lamp from your friend, it will actually cost you more after a few months if it is more powerful than you need or if it is simply an older less efficient bulb. 150W metal halides, for example, are less efficient than the best fluorescents even with a brand new electronic ballast which your fried's lamp probably doesn't have. Metal halide efficiency peaks in the 400W-1,000W range, with 400W increasingly preferred because they are available with electronic ballasts which improve efficiency by 5%-10%. So, get yourself a 42W compact fluorescent, or a couple of 25W or 30W ones if you feel you need that much light, and rig up reflectors or white baffles to make sure that most of the light ends up on your small growing area. You can grow under the standard domestic 3000K/2700K warm white colour, but if you have trouble with stretching or bolting then look for a 4100K or 6500K bulb, either as one of the two bulbs or as the only bulb.
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srercrcr
14 years ago
No no. You're paying for 1000 watts energy consumption but you get less heat from lightbulbs because alot of the energy is used to produce light (not heat). Don't confuse energy used with heat produced. Good discussion though.
bus_driver
14 years ago
Not much of the energy used by incandescent lamps makes light. 94% to 96% of the energy consumed by such lamps is heat. So 4% to 6 % is light. Lamp life is short due to the heat.
baymee
14 years ago
What about the Guinness book of records where a closet light has been burning since the teens? :)

They don't last long because the filaments are so thin. Plus, they'd never sell any new ones. :)
jake2007
14 years ago
To answer the original question:

Yes.

All of the energy, including the small amount that becomes light, turns into heat.
echo2400
Original Author
14 years ago
I have a new energy star ranch with zoned heating to the finished but unused basement. And I have ceiling fans running in the rooms that I spend the most time in. And I would enjoy having extra lights on in the house. I'm going to use the celing fans with the 10' ceilings any time i'm in the room, so here comes the questions.
Solar Comfort and Edenpure use bulbs to heat. That's what got me started on this. The Solar Comfort use the same heat bulbs as farmers use for the animals so they are cheep and easy accessible. And the Edenpure uses bulbs.
If I am running a space heater with a ceiling fan running in the room 24-7, how does the heater fan figure in? wouldn't I get the same heat out put without the heater fan? And running that fan would actually waste electricity?
What good does a copper heat exchanger accomplish in space heaters?
What about the oil filled heater? They may be safer and hold heat longer but it takes longer to heat up so no real heat gain right? Other than what is gained by using no fan.
What about halogen Bulbs compared to incandescent?
What about Quartz tubes?
I have a finished basement with 36 can lights with 60 watts incandescent flood bulbs. When not using the basement and needing very little heat down there. If I used the can lights to add some heat in basement, with most of the heat radiating to the upstairs and help keep the hardwood floors warmer.
I used to use cf's in the summer and incandescent in winter. I have been using LED bulbs were I can get by without high wattage bulbs. I'm getting about 40 watts for 1.5 watts used. ($5-$10 at Walmart and Costco.) I'm now thanking of using led's in the can lights year around because incandescent heat at ceiling would loose more heat. Then use Incandescent in the winter in lamps and chandeliers and be liberal about leaving them on when needing heat. What do you think?
baymee
14 years ago
Only a simple observation. Fluorescent and LED lights put out wattage, but I'm not sure if that is pure heat.

Incandescent, oil filled heaters, and any device that uses resistance wire produce 100% heat. No chimney flue losses are involved. Heat is heat. It produces so much per Kilowatt hour.

Electric, with no chimney, is 100% efficient.

When you get into the meaning of 100 watts of electric heat and 100 watts of light, I defer to others.
jakethewonderdog
14 years ago
There are a lot of confusing questions... let me try to clarify some things:

1. All energy becomes heat. All of it.
So, the electrical energy going into a light, a fan, a stereo, etc. all becomes heat. Any electrical device is 100% efficient (close enough) at producing heat. As the previous post said, a device that has a flue will not be 100% efficient at producing heat that goes in your house... because some of it goes out the flue.

2. The electrical energy that is actually consumed by an electrical device, measured in watt hours, is the amount of heat it produces. period. The only exception to this is a heat pump. So, a 1500 watt Edenpure heater produces exactly as much heat as a 1500 watt hair dryer or 1500 watt vacuum cleaner or 15 100 watt light bulbs. The EdenPure and Solar Comfort heaters have a higher coefficient of BS and are made of special wallet lightening materials... but other than that, they produce the same number of BTU's per watt hour of electricity as my Kitchen Aid mixer.

3. Believe it or not, visual light output isn't measured in Watts as we commonly think of it (it is a measure of radiant flux). We use the amount of light an incandescent bulb produces as a common reference point, but it's a really poor reference.
So, for example, we say that a 26 watt florescent bulb produces the same light output as a 100 watt bulb... but the amount of light a 100 watt incandescent bulb produces varies a great deal. One of the factors is the voltage applied to the bulb and the voltage at which the wattage rating was given.

On the other hand, a 26 watt fluorescent bulb produces 26 watt hours of heat while a 100 watt bulb produces 100 watt hours of heat. If it's light that you are after and not heat, you want the thing that produces the most light for the least amount of electricity. A kilowatt hour (1000 watts for an hour) is equal to 3413 btu's.

BTW: large office buildings often don't need heat in the core of the building because of all the heat from the lights, computers, etc.

The actual measurement of light is very complicated - there are parts of the light spectrum that we can't see (infrared and ultraviolet, for example) The common measure you will likely see in comparing light output is lumens. That is a more apples-to-apples measure of light output for average people if you don't use the inexact "incandescent equivalent".

Given that information, can I help you narrow down your questions a little?
garyg
14 years ago
Light bulbs do not produce watts, they consume watts.

The wattage can be converted to btu's, which is a measure of heat.

The light emitted by a light bulb is measured in lumens.
baymee
14 years ago
That is true, but electric baseboard units are specked by watts. So, a 1000 watt baseboard unit is the same as a 1000 watt bulb in BTU value.
weedmeister
14 years ago
The difference is how efficient that baseboard heater is in converting the heat energy into warm air versus a bare light bulb.

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