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Peakflows 2021 4c


  • Scale inhibitor
  • Chemical-free and environment-friendly
  • Increases flow rates
  • For up to 6 gpm
  • Residential and light commercial
Navien PeakFlow® S scale prevention system
PeakFlow® S certifications
  • Scale inhibitor
  • Chemical-free and environment-friendly
  • Increases flow rates
  • For up to 6 gpm
  • Residential and light commercial
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Navien PeakFlow®S... the complete package


Heavy-duty painted metal mounting bracket and fasteners


Durable dual rubber O-rings for better leak prevention


Easy to install filter cartridge with longer PP filter and PeakFlow scale crystallization media


Full circle molded plastic filter housing wrench

PeakFlow® series video

This highly recommended environmentally friendly system treats hard water issues to address the water quality going into your Navien units, other water-related products and your water supply lines. A “must buy” in areas of hard water. Scale build-up from hard water is the biggest single reason for unit failures.

PeakFlow S prevents scale by converting dissolved hardness minerals into powerless particles that will not attach themselves onto any of the components in the system. PeakFlow S, when sized correctly for the installation, will help to ensure the longevity of your system, and help eliminate hard water quality problems.

Maximum pressure
90 psi/6.2 bar
Maximum temperature
Minimum temperature
Inlet/outlet connections
3/4" FNPT
Service flow rate
up to 6 gpm (23 lpm)
Continuous flow rate
Up to 4 gpm (15 lpm)
Media cartridge does not have a grain removal capacity. However, other contaminants present in the water will gradually degrade the effectiveness of this cartridge (see Operation and Maintenance below)
Unit weight
15 lbs/6.8 kg
Unit size
7" x 13-1/2"
Media replacement period
2 years
6.5 to 8.5
Hardness (maximum)
75 grains (1282 ppm CaCO3)
Water Pressure
15 psi to 90 psi (1.03 bar to 6.2 bar)​
40°F to 100°F (5°C to 38°C)
<2 ppm
Iron (maximum)
0.3 mg/l
Manganese (maximum)
0.05 mg/l
Oil & H2S
Must be removed before PeakFlow™S
Must be removed before PeakFlow™S
Silica (maximum)
20 ppm* - PeakFlow media does not reduce silica scaling. While silica tends to have a less significant effect on scale formation than other minerals, it can act as a binder that makes water spots and scale residue outside the plumbing system difficult to remove.
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