Installation sequence -- AQ-4100NSF
The Aquasana AQ-4100NSF is a two-piece system: the filter housing (which connects to the shower arm) and the showerhead (which connects to the filter housing outlet). Install in this order: (1) Apply Teflon tape to the shower arm threads. (2) Thread the filter housing onto the arm clockwise -- hand-tighten plus a quarter-turn with wrench. (3) Apply Teflon tape to the filter housing outlet threads. (4) Thread the included showerhead onto the filter housing outlet clockwise -- hand-tighten plus a quarter-turn. (5) Turn on the water and perform the first-use flush.
AQ-4105 installation -- with massaging head
The AQ-4105 installs identically to the AQ-4100NSF with the same in-line filter housing. The difference is the showerhead head connected to the filter housing outlet -- the AQ-4105 head has a spray mode selector for the 7 spray functions. After installation, test all 7 modes. The filter housing sits between the arm and the head -- total assembled length is approximately 5-7 inches from the arm connection to the spray face, which is accommodated by any standard arm installation.
First-use flush
Run the shower at full flow for 3-5 minutes before first use. The first 1-2 minutes may show black or grey flecks from the activated carbon stage -- this is normal and clears within 3 minutes. Do not drink or use the shower water for personal rinsing until the flush is complete and water runs clear. The filtration begins working immediately after the flush period.
Filter cartridge replacement -- AQ-4100NSF-R
The filter cartridge seats inside the filter housing. To replace: (1) Unscrew the filter housing cap (counterclockwise) with a filter wrench (if required -- some installations allow hand removal). (2) Pull out the spent cartridge. (3) Insert the new AQ-4100NSF-R cartridge. (4) Replace and tighten the housing cap (hand-tighten plus a quarter-turn -- do not over-tighten or the cap will crack). (5) Run a 3-minute first-use flush. The housing cap O-ring must be inspected and reseated at each cartridge change -- a displaced O-ring allows bypass water around the cartridge.