Hi everyone! This is my first post on TFP. I'm hoping there are some brilliant minds out there that can help sort out some issues I'm having with my IntelliFlo VF...
My IntelliFlo cannot seem to run any flowrate below 30gpm, and this is only possible with the APC connected - without the APC the minimum flow jumps up to 40gpm! Having done several meterings on my pool circulation system, it seems that this issue has more to do with either rpm's or dynamic head than with flow: for example the above flowrates both happen at around 1420rpm and usually about 8ft of head - anything less and the pump continues to ramp down speed until it either reaches 895rpm, or indicates "system block" at around the same rpm. The pump also begins to shake below these parameters.
The clean filter status also always remains at 0%, despite doing a proper backwash cycle (on the IntelliFlo - cartridge is cleaned by hosing down) ; the pressure gauge on the filter does indicate an increase, as do rpm's/wattage over time. I only mention this because I think this issue may be related. My PB was convinced that the drive is at fault and had it replaced. The flowrates/rpm and pressure readings (TDH) are all the same with a clean filter, and the clean filter status still remains 0% at all times.
I have experimented by removing the cartridge filter element, the APC, the return line attachments (1x aimflow and a PoolSkim), even temporarily replacing the suction line/return line with cheap 2" pipe straight to the pool to try and isolate a plumbing problem. It was also suggested that I check the impeller for blockage - I dismantled the volute assembly, and did not find any blockage or anything else that would indicate an issue.
The pump was installed long after the pool was built (i.e a retrofit). The plumbing was terrible, and I set about designing an efficient layout and upgrading it. Initially I replaced the 2" suction line with 2.5" (2x 45* elbows) - eliminating 8 hard 90* elbows. At the same time I replaced a section of 2" return pipe from the pad to the pool edge with 2.5", including the Tee where the line branches to the 2 eyball returns in the pool. The next upgrade was replacing the old 3-bag sand filter with a 70ft^2 cartridge filter. I could not properly plan my layout without removing the sand filter 1st, so I ended up redoing the entire pad layout. Each time I "improved" my plumbing I got better flowrates at the same wattage, but each time I also lost lower flowrates. Initially I could run as slow as 22gpm, then 26gpm, and now 31gpm is the slowest possible flow. Again these flows correlate with about 1400-1450rpm.
The improvement allows me to complete my required turnover sooner @ the same wattage per hour, thereby supposedly saving me $$. The problem is that I cannot reduce my circulation time (8hrs per day at the moment) without having water chemistry and algae problems - also the filter would work better if I could maintain slower flowrates. Ideally I would run @ 15-20gpm for filtration, and bump up to 30-35gpm for skimming and the APC. On my 8500gal pool (x1.5 turnovers) that would be 1hrx2 for skimming/APC, and 9-11hrs for filtration = 11-13hours total. At the moment the best I can do is 30gpm for 8hours with the APC connected and running full steam all day every day.
Anyone else have similar problems? Any ideas what to do to correct/improve the situation?