150 vs. 250 watt heat issue

[prof]

Anyone have any experience with 150 vs. 250 watt metal halides? Specifically in regards to heat. 150 watt bulbs would be sufficient for my application but the cost of going to 250 watt is minimal.

Are 250 watt bulbs that much hotter?

[erick]

Not that I have had any experience with 150w MH, but I do have 3-250w MH lights that I run. My perspective is the radiant energy produce by the lamp. As you increase wattage, you also increase the par rating which realates to more light penetration. Having said that, the "brighter" the light (i.e. more par), the more energy that it puts off, which in some sense of the matter means more heat. How much more I cannot answer, but I would summize that it is a proportional relationship between wattage and centegrade/fahrenhiet. Along this line of thinking, a guess would be at least 50% hotter if not more. Now dont forget there is a difference between single and double ended bulbs. Single (mogul) bulbs are encased in an outer glass covering, double ended are not, which I am sure has some part in this little heat game also. If it is a heat issue, raise the 250w higher than the planned 150w and this should alleviate any heat issues between the two. Hope this helps....Erick

[Bill S]

An increase from 150w to 250w will pretty much produce 67% more heat to get rid of.

[erikharrison]

I had a 150 and now have a 250. 150s don't really expell much heat.... only if you brush up againts the pendant!!! Mine had fans that didn't work, but they really were pointless as that light was low heat IMO.

[txstateunivreefer]

ok i recently went from pcs to halides yes they do get hot put fans on em and your temp wont move at all look at the pics in gen reef disc of my new tank and i havent had a prob but remember by solving probs you usually make another one and it does evaporation! so get a ATO

[matt]

An increase from 150w to 250w will pretty much produce 67% more heat to get rid of.

Just curious, where did you get that figure? Has someone measured heat output of these fixtures or are you just assuming that 2/3 higher wattage means 2/3 more heat?

I would not assume that the relationship between watts and heat is that simple. It might be, but I knd of doubt it.

[hobogato]

had to run this by the physics teacher next door to check my thinking on this, but watts are joules per second, so the output of two bulbs with the same efficiency should be proportional. so, as bill said, the heat and light toghether should compare directly and the 250 watt bulb should produce more heat directly proportional to the 150 watt bulb.

[brewercm]

Are we talking same Kelvin rating bulb also. If you went from a 10K 150 watt to a 20K 250 watt there may not be the same proportional difference.
Just had to throw out the curve ball there.

[hobogato]

you are right cliff - i was asuming EVERYTHING about the two bulbs was the same except wattage. ie: color temp, brand, SE/DE, reflector type, ballast, age....