[Gooserider]

My experience with those bladder tanks on a well pump system is that they act both as pressure stabilizers AND as water storage units - I believe they typically hold 10-20 Gallons of water below the bladder, and about the same amount of air above it. (Think of a 30-50 gallon air compressor tank, w/ a bladder in the center)

The pump runs until the tank is mostly full, and the bladder is under its highest pressure. Then the pump shuts off. The bladder and tank supply the house plumbing, and the pump kicks on and refills the tank when it gets close to empty. There IS pressure variation at the faucet, but the bladder pressure change isn't that great compared to it's minimal pressure. In some setups there is a flow regulator on the feed line to the house to reduce the pressure variations caused by the bladder.

In addition to pressure regulation, this setup means that the pump doesn't need to cycle every time someone gets a drink. (remember that a well pump consumes the most energy and generates the most heat at startup. It is far more efficient to have the pump run for extended periods filling a storage tank and shut off than to have it constantly cycling on and off for short spurts)

My interpretation was that arcsylver wanted to replace the pump w/ a bladder tank, and have the water come out of the tank, circulate through the system, and return to the tank w/o further pump energy input. This wouldn't work because it's a variant on the perpetual motion machine.

What one COULD in theory do, though I don't see any significant advantage to it, is to have one of those tanks, a powerful pump, and a resevoir that had capacity like that of the tank. With some sort of regulator or valve, allow the coolant to flow from the pressure tank through the system and into the non pressured resevoir. Set the pump up on a switch so that when the pressure tank got low it would turn on and pump the coolant from the res back to the pressure tank, then shut off.

It might be a way to get rid of the pump noise most of the time (but when the pump kicked in it would be loud) It might also make sense if doing a big outdoor tank setup ala Bladerunner. I don't think it would be good for a standard system like most of us have.

Gooserider