Increasing Airflow through Condenser.
The new DC only compressor fridge I will soon have in my possession has a 92 mm computer muffin fan pulling air through only a portion(~85%) of the ~120mm tall condenser. It then blows this warmed a...
Forum Discussion
Update.
The 120 mm fan which came on my Vitrifrigo c51is was starting to bother me with it's whirring pitch.
My duty cycle was averaging below 33% for sub 38f temps since I got more insulation on the fridge, even in 80f ambient. This was with the 270 ohm resistor removed and 1 5/16" to 1.5 inches of insulation added to the exterior except top and bottom which got only 3/4" extra.
I found a 120 mm fan which used ~1/5 the amperage (0.05a)of the fan which came with the Vitrifrigo. It moves 2/3rds the air but with nearly the same static pressure rating and a few db quieter.
I first mounted the new fan on the condenser sucking air through it in the same orientation as it came, and found the quieter fan was barely quieter. Then I removed the fan and mounted it so it would push the air through the condenser and it was much, much quieter.
I have been closely monitoring duty cycle since installing the New fan in this orientation.
While the compressor was initially running about 30 seconds longer than I was used to seeing ~ 5 minutes ON, the OFF cycle went from 12:35 max in low 60's ambients to 14:55 OFF average in low 70's ambients. The box temps have kept dropping, and I keep dialing back the thermostat in small increments.
The new fan is rated 18 cfm slower, and while the slightly increased run time was not hoped for, yet kind of expected, the time off between compressor on's has dramatically increased, and my duty cycle has been at or below 25% since the fan install.
The new fan is not as quiet as I hoped, but the noise is more of a whoooosh than a high pitched 'whirrrrr'.
Latest cycles were:
4:40 ON followed by 19:50 OFF
4:50 ON followed by 18:20 Off
2:45 ON followed by 19:47 OFF
, but ambient temperature is now dropping to 62.5f, and I am now at 2 of 7 on the dial for 36f degree box temps where 3 to 3.5 has been the norm.
These results were not expected. I did not expect an improvement with a slower fan, I was hoping for no change in duty cycle. It's much less amp draw is an additional benefit.
I have bent the my old Fridge's stainless steel door panel in to 90 degree angle and mount it over the compressor to funnel the air across the compressor and controller, as well as protect the copper tubing from installation/ removal stress. Perhaps this, with the new fan pushing air through the condenser and the stainless tunnel is the reason for reduced duty cycle. I would expect if this was the case, then the on cycle would have shortened and the off cycle would have remained the same, So I really have no Idea.
The New fan has some minor restriction behind it within the cabinet which I will reduce tomorrow. It also came with a resistor cable to lower noise and CFM more, down to ~ 43 CFM and 5 less Db. The fan, a Noctua NF-F12 PWM is not cheap at 20$, but I am impressed with the engineering, customer service, website, and the performance can't be argued with.
The 120 mm fan which came on my Vitrifrigo c51is was starting to bother me with it's whirring pitch.
My duty cycle was averaging below 33% for sub 38f temps since I got more insulation on the fridge, even in 80f ambient. This was with the 270 ohm resistor removed and 1 5/16" to 1.5 inches of insulation added to the exterior except top and bottom which got only 3/4" extra.
I found a 120 mm fan which used ~1/5 the amperage (0.05a)of the fan which came with the Vitrifrigo. It moves 2/3rds the air but with nearly the same static pressure rating and a few db quieter.
I first mounted the new fan on the condenser sucking air through it in the same orientation as it came, and found the quieter fan was barely quieter. Then I removed the fan and mounted it so it would push the air through the condenser and it was much, much quieter.
I have been closely monitoring duty cycle since installing the New fan in this orientation.
While the compressor was initially running about 30 seconds longer than I was used to seeing ~ 5 minutes ON, the OFF cycle went from 12:35 max in low 60's ambients to 14:55 OFF average in low 70's ambients. The box temps have kept dropping, and I keep dialing back the thermostat in small increments.
The new fan is rated 18 cfm slower, and while the slightly increased run time was not hoped for, yet kind of expected, the time off between compressor on's has dramatically increased, and my duty cycle has been at or below 25% since the fan install.
The new fan is not as quiet as I hoped, but the noise is more of a whoooosh than a high pitched 'whirrrrr'.
Latest cycles were:
4:40 ON followed by 19:50 OFF
4:50 ON followed by 18:20 Off
2:45 ON followed by 19:47 OFF
, but ambient temperature is now dropping to 62.5f, and I am now at 2 of 7 on the dial for 36f degree box temps where 3 to 3.5 has been the norm.
These results were not expected. I did not expect an improvement with a slower fan, I was hoping for no change in duty cycle. It's much less amp draw is an additional benefit.
I have bent the my old Fridge's stainless steel door panel in to 90 degree angle and mount it over the compressor to funnel the air across the compressor and controller, as well as protect the copper tubing from installation/ removal stress. Perhaps this, with the new fan pushing air through the condenser and the stainless tunnel is the reason for reduced duty cycle. I would expect if this was the case, then the on cycle would have shortened and the off cycle would have remained the same, So I really have no Idea.
The New fan has some minor restriction behind it within the cabinet which I will reduce tomorrow. It also came with a resistor cable to lower noise and CFM more, down to ~ 43 CFM and 5 less Db. The fan, a Noctua NF-F12 PWM is not cheap at 20$, but I am impressed with the engineering, customer service, website, and the performance can't be argued with.
