Pszemol wrote:

So how would it prevent pump cycling on/off ?

There's not very much volume in the RO-DI unit and tubes. Just a little
bit of leakage would drop the pressure enough to trigger the pump.

These pressure switches are rated at 40psi, but they probably turn off
at 40 and back on at 38.

Adding a reservoir allows more leakage without dropping the pressure
significantly.


I see... so you did not realize yet that it will not work this way :-)

Fair enough. But the pressure switch is after the RO/DI (not before).
It turns off the pump when there is a back pressure at 40psi which shuts
down the RO/DI unit.

I see what you're saying, and that would work if both the reservoir and
a 80psi pressure switch is located at the front. I don't think it's
done that way, because you wouldn't have a reservoir of processed water
ready to dispense at a tap.

That's my understanding, but it's subject to change. (Hopefully, this
weekend.)

--Kurt