Push Or Pull Muffin Fans (?)
Lesson time for Mex. Is there a difference? Some more suitable for case exhausting than others? Push air in? Pull air out? I take advantage of natural convection effect but if some fans are more ef...
Forum Discussion
My compressor fridge came with a 120mm condenser, and a cheesy airflow 120mm fan attached to it, pulling air through the condenser, which looks like a car radiator.
This cheapo sleeve bearing airflow fan was louder than the compressor, and it drew 0.12 amps.
I removed this fan, and replaced it with a Noctua NF-F12 fan. 0.05 amps, and mounted it to push air into condenser instead, but a quick test revealed it did not like to bemounted in a pulling orientation, as it was loud and did not seem to move much air.
Pushing and installed in the cabinet enclosure designed for fridge, the Fan could no longer be heard.
Compressor duty cycle was reduced also, from ~5:30 on to ~4:45 on, a reduction in compresor run time of about 45 seconds each time it cycled on, which is a significant improvement.
5 years after tis modification to the compressor fridge's ventilation, the NF-F12 got relocated to exhaust the fridge and electrical cabinets together, running 24/7, and the new Noctua A12x15 installed on condenser, effectively a push pull scenario. I did not time duty cycles after this change, but the fridge peformance has always been impressive.
My one 92MM Delta fan used as an interior directional air circulation fan has a filter on it, but instead of one layer of material close to the fan, I made a filter sock extending 6 inches behind the fan with 4 inch deck screws keeping it from getting sucked inward into impeller. When filter gets loaded it can suck the sides of the filter inward, but airflow does not seem to be impacted all that much.
Noctua's latst fan, the A12x25 is designed for both good static pressure rating and good airflow. The tips of fan blade are 0.5MM from the case. I eagerly await the arrival of the 3000 rpm industrial model, which I have no idea if it is actually in the works.
If I were seeking to cool a hard working powersupply and noise and amp draw was not a factor, A Delta 120MM fan 252 cfm fan on the lid pushing in would be the call.
I consider my RSP-500-15 to be working pretty hard, and Noise is a primary consideration. I added a Noctua 60Mm fan pushing in, and a Noctua 80Mm fan sucking out, in addition to the very high rpm 40MM provided fan suckin out.
I have a thermistor on an internal heatsink.
I tried reversing the flow of the 60 and 80Mm fans, and then both pushing and then both pulling. The one internal heatsink read coolest with the 60mm pushing and the 80mm pulling, but the heatsink was also directly under the 60mm pusher.
The loud 40Mm meanwell fan only comes on aver 32 amps output, and the 80Mm exhaust puller fan next to it seems to have its airflow reduced by 2/3 when it does come on.
My run times above 32 amps are limited. Without the Noctua fans added to case lid, the 40Mm fan would cycle on and off at just 6 amps of load, and was loud enough to be intolerable.
I could likely improve results further, but see no need as there is little doubt the power supply runs much cooler than required to remain happy, and I have also vastly increased the heatsinking on the casing opposite the transistors. These certainly get warm at max output, and I 'could' attach 60MM fans to them. But max output rarely lasts more than 30 minutes and the internal heatsink's thermocouple has yet to exceed 125f.
Any test results of a push pull sceanrio on a power supply will depend on the fans themselves, and where they are located. If I were to only add one fan to a powersupply, it would be a static pressure fan pushing in on the opposite side of the internal fans that suck out, and I would not go batcrap crazy with the rpms of chosen fan.
Its great to have a powerful high rpm fan, provided one can throttle it back when max airflow/pressure is not required.
Throttling can be done with a pwm on the power leads, or on the blue wire of a 4 wire PWM fan, or by voltage on the power leads.
I've used all three methods and the 4 wire PWM fan with the blue wire fed a pwm signal is my favorite method, using Noctua industrial fans and their speed controller.
But the high rpm Delta fans are powerful monsters and it is occassionally good to let Godzilla loose, but instead of shootng fire he shoots ice which likely makes 'him' a 'her'.
This cheapo sleeve bearing airflow fan was louder than the compressor, and it drew 0.12 amps.
I removed this fan, and replaced it with a Noctua NF-F12 fan. 0.05 amps, and mounted it to push air into condenser instead, but a quick test revealed it did not like to bemounted in a pulling orientation, as it was loud and did not seem to move much air.
Pushing and installed in the cabinet enclosure designed for fridge, the Fan could no longer be heard.
Compressor duty cycle was reduced also, from ~5:30 on to ~4:45 on, a reduction in compresor run time of about 45 seconds each time it cycled on, which is a significant improvement.
5 years after tis modification to the compressor fridge's ventilation, the NF-F12 got relocated to exhaust the fridge and electrical cabinets together, running 24/7, and the new Noctua A12x15 installed on condenser, effectively a push pull scenario. I did not time duty cycles after this change, but the fridge peformance has always been impressive.
My one 92MM Delta fan used as an interior directional air circulation fan has a filter on it, but instead of one layer of material close to the fan, I made a filter sock extending 6 inches behind the fan with 4 inch deck screws keeping it from getting sucked inward into impeller. When filter gets loaded it can suck the sides of the filter inward, but airflow does not seem to be impacted all that much.
Noctua's latst fan, the A12x25 is designed for both good static pressure rating and good airflow. The tips of fan blade are 0.5MM from the case. I eagerly await the arrival of the 3000 rpm industrial model, which I have no idea if it is actually in the works.
If I were seeking to cool a hard working powersupply and noise and amp draw was not a factor, A Delta 120MM fan 252 cfm fan on the lid pushing in would be the call.
I consider my RSP-500-15 to be working pretty hard, and Noise is a primary consideration. I added a Noctua 60Mm fan pushing in, and a Noctua 80Mm fan sucking out, in addition to the very high rpm 40MM provided fan suckin out.
I have a thermistor on an internal heatsink.
I tried reversing the flow of the 60 and 80Mm fans, and then both pushing and then both pulling. The one internal heatsink read coolest with the 60mm pushing and the 80mm pulling, but the heatsink was also directly under the 60mm pusher.
The loud 40Mm meanwell fan only comes on aver 32 amps output, and the 80Mm exhaust puller fan next to it seems to have its airflow reduced by 2/3 when it does come on.
My run times above 32 amps are limited. Without the Noctua fans added to case lid, the 40Mm fan would cycle on and off at just 6 amps of load, and was loud enough to be intolerable.
I could likely improve results further, but see no need as there is little doubt the power supply runs much cooler than required to remain happy, and I have also vastly increased the heatsinking on the casing opposite the transistors. These certainly get warm at max output, and I 'could' attach 60MM fans to them. But max output rarely lasts more than 30 minutes and the internal heatsink's thermocouple has yet to exceed 125f.
Any test results of a push pull sceanrio on a power supply will depend on the fans themselves, and where they are located. If I were to only add one fan to a powersupply, it would be a static pressure fan pushing in on the opposite side of the internal fans that suck out, and I would not go batcrap crazy with the rpms of chosen fan.
Its great to have a powerful high rpm fan, provided one can throttle it back when max airflow/pressure is not required.
Throttling can be done with a pwm on the power leads, or on the blue wire of a 4 wire PWM fan, or by voltage on the power leads.
I've used all three methods and the 4 wire PWM fan with the blue wire fed a pwm signal is my favorite method, using Noctua industrial fans and their speed controller.
But the high rpm Delta fans are powerful monsters and it is occassionally good to let Godzilla loose, but instead of shootng fire he shoots ice which likely makes 'him' a 'her'.
