Satamax, I appreciate your help! Sorry for the lag here, but had a death in the family. Now it is time to return to living... Besides, it is going to be in freezing temps end of the week, and I don't want to kill all the tomato plants..
Can you tell me which would be better: a barrel "bell" system after the manifold, or three 7' lengths of 6" pipe? Would I use a pair of fullsize 55gal drums, or the smaller 30gal sized barrels?
Would a 6" pipe going from the manifold into the bell barrel work good or does it need to be bigger? I'm assuming that I should use a pair of whole barrels instead of cutting them in half (how would i seal the "floor" then)? Would i cut the entire ends out between the two barrels, or make a bottom exit from one to the other?
Then the 6" pipe exiting the end of the bell barrels should be located low on the end to force the hot air to expand inside the bells, right? Is there any magic distance for inlet or outlet?
Finally, why couldn't I just mix up quikrete to form the mass around the barrels?
Thanks for your help!!