Testing different solar heaters part 3
Channel: Melb Green Ideas
Date: 2015-01-16

We tested two different Solar Heater designs and compared the results. We found the most important feature was high air flow through the cans. 

It was bright warm day in Melbourne (33c, no cloud) and I testing both by Solar Heaters. They both have identical glazing area under the same box dimensions and use the same fan (Cool Master 115mm, 12volt, 95cfm). The key difference is the way the air hits the cans. 

The heater design on left forces air to travel through cans that have a small hole in the top and bottom (tube design). The heater design on the right uses two separate layers of cans and the air travels between the layers of cans (layer design). 

We found that under the same conditions that the tube design produced 7c more temperature rise for the same air flow. On face value it seems like the tube design is the winner. 

But...Less air was getting into the layer design so if the layer design had a similar air intake to the tube design it might of increased its performance. 

Also I found later that the input temperature going into the tube design was a few degrees warmer than I thought as it was sitting on hot concrete. So the two designs really neck and neck. 

Conclusion both designs work well. Better controlled testing required in future.  

Building implications

Tube Design uses less cans but requires more work to build

Layer Design uses more cans but requires less work to build