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Making a shroud question??

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Feb 4, 2002
I'm gonna be making a shroud for my heatercore. I have 2 92mm panaflo's that fit perfectly on my heatercore vertically.
I'm gonna center them left to right and make a shroud to hold them about 1" from the surface of the radiator.

the questions are these 2


which is the better shroud design. the fan would of course be centered, it's just a quick sketch cause I'm lazy.

2) with both of these designs, do I want my fans sucking or blowing??

Use the one on the left if you're sucking air through it. Use the one on the right if you're pushing air through it. Pushing air is better. I'm getting my info from what I see at work, Residential HVAC.
The shroud directs the air to the radiator. Fans have a dead spot directly in the center of the fan. By placing the fan say 1" from the radiator will improve the flow. If you mount the fan flat against the radiator you will restrict the air passing through the fan. The shroud on the photo above is the brass metal work that the fans are mounted to.
wow, nice heatercore. for real!
and design #2 would be better, it makes the air pull through the core better and more evenly, but put it in the middle, not off to the side. and i have to disagree, if u only have 1 fan, pulling is more efficient. I'm sure someone can explain why in more detail if u like, im to tired.
If you're pulling the air, you do not have to direct it. It will direct itself as long as your shroud is air tight. Therefore it wouldn't matter which one you used.

If you're pushing the air, you do have to direct it. If you don't, you will get a twirling affect with the air causing back pressure. Therefore it would be better to use the one that isn't the box. The one on the right of your picture.

It is better to push the air (if you are concerned with efficiency) because it causes more of a friction, helping the heat absorbtion.
The most common method I've read here is push and pull with 2 120mm fans with the 7volt mod. To tell ya the truth, that's what I would do due to the fact that is probably the best effeciency vs. noise.

You may be right on pulling being the best though. I'm just going on my little amount of common sense and laughable understanding of physics. I would really like to know, if pull is better, why.

You know all heat pump air conditioners (that I've seen.. and I've seen a bunch) pull the air over the evap coil, so you may have something there.

Then again, most gas furnace with ac applications have the air push over the coil.

You know, I betchya it doesn't make a differance either way. I mean.. you have the same volume of air going at the same speed. Why would it matter?

And as for the push pull method.. I wouldn't do it without a volt mod. By doing a push pull, your fans will still move the same amount of air but the rpms will be much faster. Could cause the fans to overheat or die prematurely.
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