GBComp,

I do really hope this is your last posting because you are really not adding any value. All anyone is asking for is verifiable data, not invective. Data that will help us make the best choice.

And for your information, I am not affiliated with any company (neither Renewability, GFX Technology, Watercycles, Eco-GFX, or Eco-Innovations). I don't know Dana1 either, though I appreciate his positive contributions to this thread and admire his patience and self-control. I am simply a homeowner who is doing his homework on a very interesting technology. I would love to have independently verified data on Thermodrain in order to help make the best buying decision. Unfortunately that does not appear to be available right now. Shouting that they are great and the others are frauds, and attacking members on this thread who contributing positively does not advance your cause nor the cause of Eco-Innovations. Amen.

Great topic, hate to settle the heart rates in this forum but does anyone know why these drain heat recovery units have to be installed on a vertical pipe? Let me qualify that by saying my septic system is quite shallow and the height difference between my shower drain and the pipe that goes to my septic system is less than a foot and a half over about 8 feet. Pipe is much closer to horizontal than vertical, which I assume means the water flows through it at a slower rate and should make it better for exchanging the heat. Many of the web sites for these products say explicitly to install them on vertical pipes. I have none. Am I SOL??

The vertical pipe requirement is to maximize the surface area contact on the drainwater side of the heat exchanger.  More than a few degrees out of plumb the surface tension of the (slightly soapy and therefore low-surface-tension) drainwater isn't enough to get it to film-over much of the drain-pipe surface.  The more vertical it is, the better it spreads, clinging to the surface of the pipe. When the surface area is maximized, the boundary layer of that thin film of water isn't insulating the rest of the water much and the heat exchange efficiency is maximized.  Horizontally the surface area contact area is reduced by 80% or more, and most of the water flows over the fairly low turbulence boundary layer that IS in contact with the copper, for  avery low efficiency heat exchange indeed.

Also, by being vertical it won't gunk up and develop an insulating layer of crud on the drainwater side quickely the way a horizontal unit would.
 
There is one vendor of a plate-type horizontal drainwater heat recovery unit in N. America:  Ecodrain ( http://www.ecodrain.ca/ )  don't know what to expect for actual performance numbers, but they claim to have mitigated the potential clog issues withe some sort of magic-mousemilk slippery coating. (How well THAT works in practice is also TBD.)