Our pool is nearing completion, but a problem has surfaced. When the pump (a 1hp Superflo two-speed) is operating on low speed, it's hit or miss as to whether or not the IC20 will function. Sometimes it works, but often the Easytouch panel (as well as the red light on the cell) will indicate a flow error. If I switch to high speed, it works fine, but when I go back to low speed, it will usually give the flow error within a few minutes (though sometimes it works on low speed for as long as an hour or two).
Backwashing the filter (sand) helps, but after a day or so (and maybe only a tiny increase in PSI) it's back to being unreliable.
I suspected the problem is related to how the cell is installed:
This pic was taken before the cell was installed... it's positioned in place of that horizontal section of PVC right after the filter. It just barely fits there, so there's an elbow immediately before and after the cell. I noticed in the manual that they suggest "for best flow sensing, provide at least 12"-18" of straight pipe in front of the cell inlet", which I clearly don't have. Presumably turbulence from the elbow is throwing off the flow sensor. I talked to the builder about replumbing it, which he sounded receptive to, but he spoke with his Pentair rep, who indicated that he didn't think it would help, as the pump on low speed wasn't going to provide enough flow regardless.
The suggested solution was to simply run the pump on high speed most of the time, which I am not happy at all with... the whole point of a two speed pump is to save energy by running it on low speed! But perhaps the rep is right... maybe this pump can't provide enough flow to consistently keep the cell happy. I just would have thought that I'd see more people complaining about this problem if that were the case, so I'm not convinced that turbulence from the 90 isn't to blame... if flow is otherwise just barely sufficient, the non-smooth flow coming off that elbow could be causing the flow sensor to not be closed all the time.
As you can see in the photo, there's no easy replumbing solution... adding several more elbows (to get to the space needed for the 12 - 18 inches of straight pipe) seems unavoidable. I think the person who originally plumbed it didn't realize that a SWG was going to be installed (that equipment had not yet arrived).
Another solution that I proposed was to swap out the pump for a variable speed (which is more expensive, of course)... that way, rather than run the two-speed pump on high, I could just increase the speed slightly until the SWG is kept happy.
Anyway, the short version... should a 1hp two-speed pump on low provide enough flow for a SWG, and how important is it to have that straight section of pipe before the cell?