Hoot chute in terms of CFM

[johnyew]

I've emailed Hoot before asking about his article and he refered to me to this forum. After reading the thread, it seems that the AC model is the one to get. However, I'm in Hong Kong and have to use the 230V model.
The question is this, does the 140cfm model running at 50% equal to the 60cfm model running at 100%? Will the 140cfm@50% last longer than than the 60cfm@100%? Finally, will there be a significant noise difference between the two?
As you can see from Grainger, the 140cfm model is about US$20 more than the 60cfm model.
Thanks.

[PDL]

Originally posted by johnyew
I've emailed Hoot before asking about his article and he refered to me to this forum. After reading the thread, it seems that the AC model is the one to get. However, I'm in Hong Kong and have to use the 230V model.
The question is this, does the 140cfm model running at 50% equal to the 60cfm model running at 100%? Will the 140cfm@50% last longer than than the 60cfm@100%? Finally, will there be a significant noise difference between the two?
As you can see from Grainger, the 140cfm model is about US$20 more than the 60cfm model.
Thanks.

Well, I would think there would be no difference in performance between 115 and 230 volt. The CFM ratings are the same and for all intent and purposes the 140 at half speed would be 70 CFM.
Anyway, I use a 60 CFM and the speed is at about 75% so the 140 CFM would only need to be run at something less than 50%.

[johnyew]

if it's a linear reduction, then I would be getting the 60cfm model.
Has anybody looked into the life expectancy when comparing 140cfm@50% with 60cfm@100%?
Thanks for the reply.

[Hoot]

Johnny, what is the grainger part number of the 230VAC blower you are considering? There are more factors influencing what to get than just cfm. Form factor is important also. Blowers come in all shapes and sizes, not to mention, how they mount to the case. Were you considering the 2C915? A big factor to consider is the size of the blower wheel. Larger wheels will deliver more cfm at lower RPMs. Lower RPMs equates to lower noise. Blowers with larger wheels are larger blowers. Some people have told me that they shy'd away from the Hoot Chute because of the appearance of a large blower mounted on the case cover. I have found that with my MC-462A, the cooling capacity of it tops out before my 2C647 reaches full speed. That may be due in part to the use of aluminum for the pin, the use of pins instead of fins, the fact that there is a small air pocket under the base of every pin where it is staked into the copper base, or a combination of all the above. If I had to get a 230VAC blower, I would always opt to get one with more CFM capacity than I needed and then slow it down with an AC fan speed control. Simply lowering the AC voltage will not properly regulate the speed of an AC blower. you need to use a fan speed control that varies the duty cycle of the AC waveform, while not lowering the peak AC voltage. I have not seen a 230VAC fan speed control, but I imagine they exist for countries that do not have 115VAC service. Don't skimp on the fan speed control either. The cheap ones produce horrendous EMI and make the blower hum and whine. Good ones have EMI suppression components in them.

Hoot

[johnyew]

Hong Kong uses 230Vac only. The models from the 'small centrifugal fan' section has these 230V model; 2C914, 2C915 and the 2C916.
Personally, I have less stringent demands when it comes to noise levels and I've already bought cut off wheels for the project.
I'm planning on replacing the Super Orb with an aluminium T-6061 heatsink that I had a machinist friend make for me thats similar to the MC462A. Later on if I manage to find a block of C101 copper, I may replace the aluminium HS with it.
Do you know exactly at which CFM does your hs reaches saturation? If it exceeds 60cfm, I'll get the 140cfm model then.
Thanks.

John Yew.

[Hoot]

Keep in mind that the "Hoot Chute" is a multi-purpose cooling solution. It not only cools the CPU, but provides the through-case ventilation as well. It has been a while since I did my CFM/Saturation experiments and I don't recall the exact figures now. Suffice it to say, that if you go with a blower that has a greater CFM than you need, you can slow it down, with a speed control, to suit your computing needs. When I am browsing the Internet, doing emails, or generally just fooling around, I turn down the speed as the heat generated by the CPPU and system is not too extreme. When I am running a stressing program, doing 3D gaming, doing Engineering modelling, etc, I turn it up. Of the three models you mentioned, I would recommend the 2C915. The 2C914, at 60 cfm will be running at maximum most of the time, so I don't recommend it and the 2C916 does not have a mounting flange at the output port, so mounting it would represent a greater mechanical challenge.

Hoot

[johnyew]

Hoot,
Thanks for the reply. I'll be ordering the 140cfm model.

Over the weekend, I modded my case for use with my diy aluminium hs with a Sunnon 230V 120mm fan with cardboard ducting blowing directly onto the hs. MBM5 showed a temp improvement of about 3C. However, case temps shot up by about 6C. I guess I'll have to do some more duct work to direct away the waste heat.
I also modded my Inno2 Ultra with a new CoolerMaster HSF using AS Adhesive. I have oc'ed to 315/515 but this is not the max oc.