Adding fan behind refrigerator...worthwhile??

ernie1 wrote:
Am I to understand that the cycling temps of the cooling fans are 95degF on and 130degF off?

No.

I'm not sure what the best on/off temps are, but I'll share my findings and thoughts...Over the coming year I'll test out a few different strategies with these fans to see what works best.

Assumption for my situation: I am ONLY trying to make it so that my fridge temps stay under 10F in the freezer and 40F and below in the fridge section. I am not trying to reduce propane use (although that could happen a bit) and I'm not worried about battery usage (I've got more than enough solar and the fans are low power).

First off, When the ambient temps outside are 60-70F it seems the behind the fridge fans are not even needed. Inside temps of the freezer and fridge are fine (cool enough). The cooling fans are really only NEEDED when the outside ambient temps are probably 80-85F or higher.

Data point: Without the fans running, and with outside ambient temperature of 90F, I notice WHERE I HAVE MY THERMOSTAT PROBE POSITIONED, the probe reads a max of 120F (after the boiler has been on for its cycle). Note: This will be HIGHLY dependent on where you put your thermostat probe. So I would suggest that if you add cooling fans like this, you must first determine what the NORMAL (non-fan cooled) temps are behind your fridge on a hot day with the fridge boiler on and your probe placement. For me and my placement, that temp is 120F max (in 90F ambient temps). So it gets 30F higher than ambient outside temps.

With my 120F high temp data point in mind, I have currently set my cooling fans to go on at 98F and turn off at 96F. How did I pick those temps? Let me explain... I only really want the fans to be on and running when the temps BEHIND the fridge are above 98F. So on a warmish day and the boiler on, it will heat up in the space behind the fridge and I want the cooling fans to turn on and move some of this hot air out. What I have found is that when the boiler is on (which lasts for many minutes) the cooling fans don't cool the behind the fridge cavity as much as you might think. It might cool it 5-10F compared to what it would be without cooling fans. But moving this hot air out helps the fridge to cool better and lower internal freezer/fridge temps. That is the goal afterall.

I have the cooling fans set to turn OFF at 96F. The reason for this is because I don't want to hear the fans in the morning or in the evening and the temps where I live/camp will be down to the 60-80F range when the sun isn't at its warmest/highest (mid-day).

Another data point: Overnight, with night time temps of ~60F and nobody going in/out of the fridge/freezer, (and I assume no cooling fans going on based on my 98F setting), my freezer in the morning was at 5F and my fridge was at 33F.

Hope that helps.
Chris