Hello Packard bill and Freddy,
What an ingenious idea! You both are saying pretty much the same thing, let me repeat in my words so that i'm sure i got it.
My circulators are on the supply side of the loop. The house heating loops are 3/4" pipe, and the DHW is 1" pipe ( right, a lot more flow). the Dhw does not have a tempering valve, it is controled by its own Aquastat. I keep the DHW water at 130*, which means it will call for heat at a 120*. I try to maintain Boiler water between 170 to 180 degrees. So if i put in a bypass in the supply line between the circ. and the tank and run it to the boiler return line with a ball valve i can adjust the valve to control the water temp back to the boiler. That is so simply i can believe i didn,t think of that ( being a simply minded person that i am). What this probably will do is take a longer time for the DHW to come up to temp, but who cares when it would drop the water temp to a 140* it would run a long time anyway.
Thank you very much
PS: Freddy, i read alot of your post. You should have your own show, you are one funny guy. I was rolling on the floor this morning after reading your answer to the stud finder question.