# How much heat?

Discussion in 'Lighting' started by Noam Chongsky, Jan 3, 2013.

1. #1
Last edited by a moderator: Jan 7, 2013
Approximately - how many watts of heat will a 300wCFL produce?

It apparently converts about 60% of its energy into PAR watts, so does that mean the other 40% is heat?

Or will all the energy minus the small amount taken by the plants, be converted to heat.

With a lamp that produces the light by producing heat directly it seems simple to work out but i'm very confused so please help.

2. Physics isn't my strong point - anyone got and ideas?

3. I'm not sure what your asking but light and heat will be pretty much the only energy it produces, or at least in significant amounts. same goes for hps.

if you had an hps and a CFL that uses the same amount of watts I'm sure the hps would give off more heat. logic then dictates the CFL must give off more light. not many people would agree with that, however non seem to be able to explain this phenomenon

4. I'm not sure how a % could be put on it. how do you measure light against heat? it's like comparing sound with colours. how can someone say a lamp gives more light than heat? more heat than another lamp yes but more light than heat? I just don't know how they can be compared

5. that applies to lamps which produce light by producing heat directly - CFLs and LEDs dont work on this principal -

Its very difficult to compare a HID to a CFL because of this

The mechanism in which the Electrical Potential is converted into light is completely different however the light truning back into heat should be the same - if you follow me.

I agree that a CFL SHOULD be more efficient at producing lumens than a HID but i'm not sure if they actually are - also i'm not sure how those lumens would translate into LUX/PAR rating either.

Do you understand why i've been getting so confused?

Where's a nerd when you need one??

6. I don't see how the way it converts energy makes any difference. the second law of thermodynamics dictates that energy is never lost but just converted. one system may be more efficient at converting the energy in to light but that would be because less is lost as heat. a big problem when comparing wattage is that a 125watt CFL uses about 90watts and a 150hps using about 200watts. so the watt rating gives very much the wrong impression

7. This is my concern also jetski -

Why are three 300w CFLs producing less heat than a 600w hps? Perhaps my HPS is terrible or the CFLs are massively underpowered?

The sales pitch on the website; where i bought the CFLs - goes on and on about how their units burn what they're rated as - and others don't.

They're made by plug and grow - as a UK resident grower - you must be familiar with this brand

The HPS I used to compare is a new Corona magnetic ballast 600w - with a brand new Omega - red spectrum bulb

8. some cfls are designs for plants specifically. so although I agree household cfls are designed to emit the light that is useful to the human eye the plant specific cfls should be designed to emit light that is useful to plants

hids were never designed for plants so who knows how much of their light is seen by the plants. we do know from using them that they work very well

9. I agree, this is a big problem when comparing cfls with hids. I think you need a power meter, plug it in and measure how much power its using. also worth getting a lux meter and measuring how much light the plants are receiving. initial lumens is a pointless figure when you can't have you plants right up to the bulb.

have had similar questions rattling around in my head recently. I have ordered a lux meter and a watt meter. they haven't been delivered yet though

10. Jetski your logic is flawless - I've seen a plug in Watt metre at B&Q for under Â£10 so i think i'l go and get one on monday -

How much should i look to spend on a Lux metre?

11. the one I bought was Â£12 off eBay I believe. not exactly a professional outfit but seeing as all the lamps I will be testing will be tested with the same meter it should be a fair comparison

12. i'm no physicist but energy is never destroyed, that's a basic principle.

any electricity that is not converted to light by the light bulb is converted to heat energy and motion energy. perhaps there are even other kinds that i don't know about.

whatever the original input energy is, minus the amount converted into light, minus the amount converted to motion (and any other possible outlets) is the amount of heat dispersed.

so with the introduction of *at least* a third energy outlet, you won't get an exact 60/40 ratio.

13. I just tested 2 outta the three units and the 2700k bulb was using 309watts and the 6700k uses 299w

All i can assume is that they are much more efficient than HID or that the HID bulbs use far more watts than they say on the box.

I ran one for nearly an hour to make sure i had an accurate reading and i could still hold the bulb comfortably - in contrast - my hair lightly touched a 600 HPS bulb a few days ago (afro/bush i need it cut seriously) - and my hair was smoking!

I don't disagree with the science i just needed some reassurance when the science didn't seem to be making sense.

In theory - as the HIDs are required to be run on comparably low voltages - CFLs are more likely to be adversely affected by magnetic induction from near by current carrying conductors. - However the large stepdown transformers, required for HIDs, tend to be very lossy in regards to heat and loss through magnetic induction.

14. I used my Electricity Metre, my watch and a calculator

i realised that my metre would display the number of kilowatts used over a set period of time so i just took my measurements from there. I allowed half an hour ish for the lamp to warm up then i recorded the reading on the metre. After waiting for exactly half an hour with the lamp illuminated - i took a reading again - and did the appropriate calculations.

Will these results be valid?

My fridge and freezer were off for a few hours but i dont think anything should spoil.

15. Also i'm quite confident that the reduction in heat will mean i'l be able to get the plant withiin such a close proximity to the light source - i think the CFLs lack will be compensated for -

IMO (which is primarily based on what i've read on GC) 90% of people who use CFLs wont be supplementing in the same ways i will be -

The big grow is fine for heat as it is in a cellar so i just use HIDs

however my CFLs have been bought for a propagator tent i intend on using to flower one indica plant (northern lights x uk cheese) which is currently being veged under MH and being topped regularly to discourage height - it is currently about 20" tall and just as wide.

I have lots of 90w UFO panels (in various colours)

a 250hps spare - but no bulb ATM

I also have 2x180w LED units as well.

Considered setting up a cool tube for the 250wHPS which would be intended to be used in the 60x60x90cm tent

I have a 6 inch vortex fan but no tubing.

Nobody seems to appreciate the effects of combining different like sources - for instance

Ever tried combining a 400wMH with a 90w pure red LED panel or something similar?

The effect was better than a 600w of HPS yet the usage is considerably below 600.

16. cfls are not shit compared to hids, your just comparing them incorrectly. if you compared a hid and a cfl that use the same amount of power, one will give off more heat, so the other must give off more light, its basic physics. however most people say hids give off more light and more heat but this is impossible unless the two lamps compared are different wattage. to compare systems you have to iron out most of the variables, all but one ideally although this isnt always possible

keep in mind a 250watt hid will use way over 300watts and a 250watt cfl will use less than 200watts so cannot be compared. you may as well compare a 70w hid with a 300w cfl, you know which will come out on top

17. The heat from a HID is tremendous - we must pay for that in electricity

I heard somewhere that the Aluminium oxide ceramic that houses the gas inside a HPS bulb can reach temperatures close to the surface of the sun. Not sure how true this is TBH lol

You can run a 300w CFL on your face and it wont burn you in the slightest - i wouldn't even consider letting a 70w HID near my face - you'd be horribly scarred for life no doubt.

My initial worry was that the CFLS would produce too much heat! - they have arrived and i was quickly able to establish that they definitely wouldn't

The light they put out is incredibly bright -

I then became slightly anxious about they're actual electrical usage - but i've now established that they do use what it says on the box ~0.3kwh

they cost me 40 quid each and have a projected life span of 9000 hours

All in all - i'm pretty impressed with plug and grows 300w CFLs so far -

Totally stoked for Monday morning - when the miniature tent arrives!

18. Apart from pink apparently - how strange...

P.S. I corrected the way you spelt colour - i'm personal friends with the queen and she says she'd like you too start putting a U in it again - thankyou

19. how do you make yellow?
yellow and blue make green

20. I think he meant to say - red, blue and yellow - the primary colours.