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
bdosborn wrote:
The relay is probably overkill but the controller is way expensive to replace so I didn't want to take any chances. Plus I had the relay sitting around from another project. It's pretty surprising how much heat comes out when the axillary fan is running.
Bruce
P.S. I used a variable speed fan so I can raise or lower the fan speed. Slow=quiet, fast=noisy but moving a lot of air. I think I set it somewhere in the middle and I haven't changed it since.
When it comes to electronic controls care MUST be taken when adding in a highly INDUCTIVE device such as a relay coil. It is common practice to add in a snubbing diode or resistor across the relay coil. Doing some will reduce or completely stop the back EMF spike from damaging the control board.
Most relays do not include a snubber.
Now about this time you are thinking why doesn't the fan motor have the same issue?
Simple, any brushless type DC fan motor like you find in computers use a electronic control board built in the fan. This control board acts like a high frequency chopper and drives the motor coils in a three phase configuration. These fans do not present any back EMF spikes.
