Martin Phillips <[email protected]> wrote: >Now, consider the effect of solubility of air. Assume that the plain >accumulator is in a position where its connection is at the bottom. On >first connection to water, it's air-filled, and water goes up and down >in it. Every time some fresh water goes in, some of the air will >dissolve. Every time a tap is run, that water with the dissolved air >will leave. Over time, the air volume in the accumulator will decrease. >Unless a cunning way is present of adding air (e.g. by draining the >system in the winter or running the tank dry), the buffering effect of >the accumulator will gradually diminish.
Not quite. The pipe to the accumulator from the (my) pressurised system is a cul-de-sac. As the system pressure rises , yes some water goes into the accumulator. However, it is effectively *the same* water each time, i.e. some from the cul-de-sac pipe, as there is nothing that will cause that water to be replaced by "fresh" water from the rest of the system. That same water exits the accumulator into the cul-de-sac when the pressure falls. The water in the cul-de-sac will become saturated with air from inside the accumulator being dissolved in it, and then no more air will be taken from the accumulator. The result is that the amount of air in the accumulator stabilises. As substantiation that this happens, I've been using the same (no-diaphragm) accumulator for nearly twenty years without draining water from it, and it is still working fine. Adrian . Adrian Stott 07956-299966
