stupid question : I read carefully the 1st post and after some days I realized that obviously you should do a sandwich thing right??

sandwich: 2x devices made by martin :
1) to cope with the hot side
2) to get the cold that they deliver and to be able to get it into the loop.

In case of making it very long ( martin s device) : shouldn't it work in a bad way as the last tecs would be having water that had been already heated by the tecs before them?