Both devices install on your main water line, watch for unusual flow and can shut the water off automatically or from your phone. The differences are in how they sense leaks and how they fit your plumbing. Choose Flo by Moen if you want a choice of 3/4-inch and 1-inch bodies and readings of flow, pressure and temperature. Choose Phyn Plus if you want its ultrasonic flow sensing and pressure-wave analysis. Either one should be installed by a plumber after checking your pipe size, power and Wi-Fi.

Specs side by side

Item Flo Smart Water Monitor and Shutoff (Moen) Phyn Plus Smart Water Assistant + Shutoff (2nd Gen)
Models 900-001 (3/4 in.) and 900-006 (1 in.) One body with 1-inch NPSM male threaded ends; 3/4- and 1-inch adapters sold separately
Pipe limit Main cold line of 1.25 in. or smaller Main line of 1 1/4 in. or smaller
Placement After the meter, main shutoff and any pressure-reducing valve Single-family home or business with its own water meter
Sensing Flow, pressure and temperature; manual “Health Tests” in the app Ultrasonic flow sensor (built by Badger Meter) plus high-definition pressure-wave analysis
Power 100-240VAC outlet with continuous power within 6 ft (3/4 in.) or 10 ft (1 in.) Outlet within reach of an 11-ft cord; GFCI recommended
Wi-Fi 2.4 GHz Dedicated 2.4 GHz network, WPA2-Personal or better
Operating limits Ambient 32 to 140°F; up to 175 psi Check the installer guide for the exact unit
Smart home Alexa, Google Assistant, Alarm.com, Ring Alexa, Google Assistant, IFTTT
Add-on sensors Moen Smart Leak Detector (920-004), which can trigger the Flo shutoff Phyn Smart Water Sensors, from under $50 on phyn.com
Warranty 1 year; extended coverage through the FloProtect plan Not stated on the product page; check before buying

Sources: Moen’s specification sheets for the 3/4-inch and 1-inch Flo, and Phyn’s product page , setup requirements and product list . On October 3, 2026, phyn.com listed the Phyn Plus 2nd Gen at $550 to $600. Prices change, so check both makers’ current prices.

Fit checks before you buy

  • Pipe size and space. Measure the main line and confirm there’s straight pipe and room for the unit, unions and service.
  • Power. Both need an outlet with continuous power near the valve. Plan for a power outage, too.
  • Wi-Fi. Both need 2.4 GHz coverage where the valve sits, which is often a basement or garage.
  • Wells. Moen says to install Flo downstream of the well pump, pressure tank and any treatment equipment. If that isn’t possible, put a wye strainer with a 100-mesh or finer screen ahead of it.
  • Temperature. Moen’s Flo and its power supply can’t be installed where it drops below 32°F or rises above 140°F.

What neither one can do

Both monitor only the plumbing downstream of the valve. They won’t catch a leak in the service line before it, or a roof, drain, sump or groundwater problem. Keep the manual main shutoff working and labeled, and make sure everyone at home knows how to reopen the water if the valve closes. Test alerts and the remote shutoff after installation, with the plumber present if possible.

Sources

This comparison is based on the makers’ published documentation. Neither device was tested for this page.