A little help wanted. I've been playing with heat exchangers and have settled on a tube in shell variation. Essentilaly, its a 3/4" convoluted surface tube inside a 1" shell. all components are copper. I use it in a counter flow configuration with the solar collector loop traversing the inside tube and the storage tank loop circulationg between the tube and shell. Its 48" in total length with two pumps; an elsid for the collector loop and an .33 hp Grundfus for the tank loop.
OK, here's my question....
What should I expect for temp difference between the collector loop input and the tank loop output? My collector loop routinly reaches 140 + F. The tank loop almost always reaches between 8 and 10 degrees F less than this. Its plently of hot water for our household needs. I just don't know what to expect here.
More info - single collector with 18 sq ft area, tank is converted Sears 65 us gal electric (just can't beat that price!). all collector loop piping is 1/2" with a loop total (both ways) of 156'.
Pix available if it will help you help me.
imt