Hi mike, Sorry. I had a death in the family and totally forgot about my ac problems. I still have a problem. My system never registers filter use past 10%. I have been changing it every 6-9 months. I use a 4 in filter that should last close to 9-12 months. I have a 3T furnace in my attic. My ac indicates coil temp 65, static pressure 0 lvoltgae 236v Also I just notice that it says I had 33-limit fault 2 events. Don't know what this means. It states 2/6/2010 12:16am.. Also, on system maintenance, it indicates owner maintenance every 6 months and %used 26%. Shouldn't this be close to 75%? I certainly don't want a reminder at 26% use - even though it never gets above 10%. When the technician came, he reset it...went to 10%, then 20% and now almost 2 months later the usage is 10%. My system is 4 years old so I'm still under warranty. They are coming today to discuss adding a new return on the hallway about 15 ft away from the other 20x20 return. Would this make any difference?

"The filter was rated "Up to 12 months", Hee hee,don't count on it,the key is UP TO. Rely on routine inspections and your pressure monitor to decide when it's time to change. If a filter is dirty after only 1 month of use it's time to replace it. If a filter go's 6 months and still isn't dirty, it's wastful to change at the time. As usual,there can be exceptions,like in 6 months without becoming restricted by dirt ,prudent to make certain air isn't bypassing filter.

mas985...thanks and understand the pump affinity laws but want to find out more about the performance differences of pumps from one manufacturer to another... Out of curiousityÂI just pulled some of the pump curves for Intelliflo and my Jandy 2 speedÂ.itÂs raining here in Louisiana due to the Hurricane so nothing better to do! I think I answered my own question related to head pressure and flowÂhead does affect flow. So, when mark1969 changes to the larger return fittings with 1" openings, there will indeed be more flow and as a result, a lower pump speed can be used to deliver the same flow. Related to speed and flow using my filter gauge pressure at high speed and low speed and looking at the theoretical flow at those speeds and pressures from the Jandy curves, IÂm getting 150 gpm at high speed and 50 gpm at low speedÂa 3:1 ratio when speed is cut in half. Same with the Intelliflo curve and using the pressures reported from mark1969Â31 psi at 3,450 rpm equals 110 gpm while 11 psi at 2150 rpm equals 70 gpmÂa nearly 2:1 ratio when extrapolating to half speed. Theoretically, from the curves, it appears manufacturerÂs tune the impellers to provide different volumes ratios with speed. I donÂt have your spreadsheet handy right now which is based on real world dataÂ.does it show a 2:1 ratio consistently across pump manufacturerÂs. Also, mark1969Âfrom the Intelliflo pump curves, you should be getting higher than 39 gpm at 2150 rpm and 11 psiÂIÂm beginning to wonder if you donÂt also have a suction starvation problem that is causing the lower flow and also the air in the system. My system does not have any air regardless of high speed or low speed operation. Hope this helps.

just-a-pb: Appreciate all your expertise and advice. It is most helpful. Reason for my concern: Had a local pool shop (Pinch-a Penny) come out to clean some scale off my tile at the waterline in the pool. Used something that created tremendous foaming and sudsing. They used anti-foam and whatever to neutralize the foam,with no success and decided to break down the filter. Guy did not know what he was doing obviously and blew the pressure release valve and guage off the top of the Hayward filter. Replaced the entire top of the filter with a new guage etc. With the new guage, I am paying closer attention to what it is reading. Thank you for your very clear explanation. Still have foam, but am trying to resolve issue on my own. Pool store says they want to help me get rid of the foam, but have no confidence in their staff. They put so much other chemical in the pool, it caused the filter to gum up the DE material. Had to have the filter cleaned again within a couple of weeks. Any suggestions for getting rid of foam in pool caused by tile cleaning agent?? Any additional help would be greatly appreciated. I am done with this particular Pinch-a-Penny store. Thanks !!