Cooling fan install on a hood (96 powerquad or other)

Cooling fan install on a hood (96 powerquad or other)

I own a Corlife 96W powerquad PC light. It has 2 small coolign fans in it that I removed to clean tonight. They were dirty as anyhting. Well I clened them up and went to re-install and I forgot which way the aifrlow is supposed to go..

Both fans are on the left side of the light and on the right side there are two opening that are the same exact size but they have no fan in them....

Should I have the air flow goign from outside to inside or should I have the fans setup to blow air from inside the light to the outside??

 

I'm pretty sure the fans are supposed to blow air from outside to inside. Thats like 99% sure.

 

i have the same light and have never replaced the fans and both blow outwards.

 

That doesn't seem logical. I would figure that air is supposed to travel into the light therefore moving heat out of the exhaust vents on the other side. That's how all fans work.

 

ive never taken it apart and thats the way it came from the factory.

 

The hood acts as a plenium and the air should be pulled from the inside to blow towards the outside ..The Fans have a little arrow.

 

I am v ery confused.....

I sort of want to beleive tsouth because when I turn the fan aroudn inside its housing so that it blows air out of the housing the airflow is very low. However when it faces the other way to blow air into the housing it has more force.....

The idea is to get air out of the housing that is hot so that could be done eitehr way. however I think that forcign cool air into the space is probably more effective than blowing hot air out.

 

Will after all the yrs of desiging and installing HVAC mechanical systems I wounder why all A/C nuits are desigend to pull air over the coils and blow out into to the room or like the condensr fans always blow out on a central outdoors A/C unit or chillers ???? You do it anyways you want.. Its your's I could try to explain it to you But when I was finished a few Hrs later you'd still not know what i said. Or you could spend several yrs in a trade school and a few hundred on the school books and hrs in a class room for 3 or 4 yrs. This type of work is not a hobby

 

Same light here, never "dis-assembled" both blow out. ;D

OUCH!

 

Excuse me - Actually I am a mechanical engineer who works on environmental control systems for a living. So I have a very good background in what you are talking about.... Probably one that is better than yours.

HVAC systems are designed to pull air thru cold heat exchangers because you get a better flow path thru the heat exchanger and you get more effective heat transfer. However the cool air is what is then pushed into the room to do the cooling....

On top of that hotter air has a lower density and the less dense the air is the harder the fan has to work. You can see this by looking at the equation:

Mass Flow (lb/min) = Volumetric Flow (ft3/min) X Density (lb/ft3)

As density decreases the volumetric flow has to increase in order to maintain the same mass flow. Let me give you an example related to this situation so you can follow:

Let’s assume we are at sea level, the temperature of the air inside the light is 95F and we want to pull air from inside the lamp and force it out into the room. At these conditions the density of the air is 0.0711 lb/ft3 . Let’s assume that in order to keep the light cool we need a mass flow of 0.5lb/min. Therefore the volumetric flowrate that is required is (0.5/0.0711) or 7.03 CFM.

Now let’s assume we are at sea level, the temperature of the air inside the room is 70F and we want to pull air from room and force it inside the light. At these conditions the density of the air is 0.0745 lb/ft3 . Let’s assume that in order to keep the light cool we need a mass flow of 0.5lb/min. Therefore the volumetric flowrate that is required is (0.5/0.0745) or 6.71 CFM.

The difference is small because we are dealing with a very small fan but you can see that blowing air from the room into the fixture actually requires less volumetric flow to get the same amount of mass flow….

In this case with such a small fan it probably does not matter which way they go. The reason I asked the question and set it up the way I did was because the fan appeared to operate more effectively when it was facing inward due to the way the fan housing was designed..... I wanted to see what other people thought and if they had the fixture how theirs was operating…. They could be setup for a blow-out design but maybe not…

Hope I don’t hurt your brain with all the math and theory……