Flo vs. Phyn: Comparing Smart Water Shut Offs


Smart Water Shut Off Valves are an excellent way to protect your house, especially when you are away from home. Two of the most popular products available are Flo by Moen Smart Water Shutoff and Phyn Plus Smart Water Assistant and Shutoff. Here, we will compare the two devices, and discuss the benefits and shortcomings of each.

Buying Guide

Both Flo by Moen and Phyn Plus provide leak detection and water usage monitoring. The main selling point for these products is that they can turn off water to the entire house in the event of a burst pipe or water leak. So, although they retail for $500+, the product will pay for itself immediately if the automatic shutoff is able to prevent a single water emergency.

Flo by Moen has an app and subscription service (FloProtect) that costs $5/month indefinitely. Phyn Plus has an app that is entirely free.

Both devices integrate with a water sensor (Flo by Moen Smart Water Detector and Phyn Smart Water Sensor) that detects leaks and sounds an alarm.

Flo by Moen vs. Phyn Plus

Product Overview

Both Flo by Moen Smart Water Shutoff and Phyn Plus Smart Water Assistant and Shutoff are water shutoffs that are installed in-line at your house’s main water supply line, and can shut off the whole house’s water via an app or automatically in response to irregular usage. Flo uses a turbine, while Phyn has ultrasonic monitoring which doesn’t have any moving parts. Theoretically, this means Phyn is less susceptible to wear and buildup.

Flo by Moen has three sensors, which monitor water flow, pressure, and temperature. Indications of a leak, burst pipe, or frozen pipe will trigger an alert. Depending on your device’s settings, this alert can also automatically shut down the flow of water to your house. You also have the ability to turn off water via the app or a web browser.

Phyn monitors flow, pressure, and temperature, and also has the ability to shut off all water automatically. The system operates in much the same fashion as Flo. 

Subscription & Warranty

One big disadvantage to Flo by Moen is that many of the app’s features are locked behind a paywall. So, expect to pay $5/month indefinitely. This subscription provides more data and also upgrades the warranty from 1 year to 5 years. Additionally, Moen will pay up to a $5,000 deductible for subscribers that have water damage to their home while using Flo by Moen with FloProtect. (In preparing this article, we were unable to find testimonials of anyone who has used the $5,000 insurance deductible coverage, so we really can’t speak to the terms/conditions that apply to this guarantee).

Phyn Plus has an app that is entirely free, and provides more data than the Flo app. So you save $5/month on the pesky subscription fee by choosing Phyn rather than Flo. Phyn Plus comes standard with a 2 year warranty, but can be extended to 3 years if the device is installed by an “authorized” (Uponor Pro Squad) installer. Phyn also provides a $3,000 insurance deductible guarantee if the product is installed by a member of the Uponor Pro Squad. (As with the Flo, we really can’t speak to the terms and conditions that apply to this $3,000 deductible guarantee).

So the standard warranty (2 years w/ Phyn vs. 1 year w/ Flo) is better with Phyn, but the upgraded warranty (3 years w/ Phyn vs. 5 years w/ Flo) is better with Flo by Moen. This upgraded warranty will cost you either way, either with a $5/month subscription (Flo) or an “authorized” installer (Phyn).

Connection & add-ons

As mentioned above, Flo by Moen Smart Water Shutoff is compatible with a (sold separately) Flo by Moen Smart Water Detector. Phyn Plus is also compatible with a (sold separately) Phyn Smart Water Sensor. Unlike Flo and Phyn, which monitor the entire home, these sensors are placed in leak-prone areas (near sump pumps, underneath sinks, behind toilets, etc.) and emit an audible beep (plus an app alert) if exposed to water. Flo can also be purchased with a battery backup, which allows the device to function for more than 3 days without electricity.

With both Flo and Phyn, a WiFi connection is needed in order to communicate with the app, but the auto-shutoff function still works without WiFi. When the app is connected, you can also turn off water remotely. Because your house’s water main line is likely to be far away from your router, a WiFi extender may be required. Be sure to verify that you have a reliable WiFi signal at your water main before installing. 

A disadvantage with the Flo by Moen auto-shutoff feature is that many users report a significant time lag between the leak occurring and the auto-shutoff feature triggering. In the event of a pipe burst, a few minute delay can cause a lot of damage. The standard sensitivity will result in frequent false alarms, but the leak detection sensitivity can be adjusted. With Phyn, there are still reports of false alarms, but the monitoring system is “smarter” and performs more reliably.

App Comparison

The Moen app is well designed and functions properly. Our only real gripe here is the $5/month subscription cost. Moen has been unwilling to open-source the program, so you are dependent on Moen for app updates and software support. The Phyn app is free, but you are still dependent on Phyn for updates and support. Because the cost of the product plus installation approaches $1,000, you hope that this system lasts more than a decade. And there is no guarantee that either the Moen or Phyn app will continue to receive updates and support a decade from now.

Both apps are well designed and provide a lot of info. We love that the Flo app supports multiple phones/users, and can be set to send alerts to more than one device. We have tested smart home devices that only allow one login, and it makes no sense to design an app this way. Phyn scores points for allowing multiple houses/systems on the same app login, which makes it an ideal device for landlords or owners of vacation properties. 

Overall, the Phyn app provides more data, and provides it in real-time with minimal delay. If you want to take a deep dive into water use analytics, Phyn is your best bet. For routine monitoring and normal use, either Flo or Phyn will do.

Installation process

Installation of both devices is straightforward, but depends on the homeowner’s level of savvy. Both Moen and Phyn recommend installation by a professional plumber. Because the warranties are dependent on “proper installation,” the company always has the ability to blame DIY installation for system failure, and void the warranty. But a handy homeowner should be able to install either system, as long as they are comfortable cutting into the house’s main water line.

As mentioned above, Phyn tries to entice you to hire a professional installer by extending the warranty and offering insurance deductible coverage if the device is installed by an Uponor Pro Squad plumber.

Monitoring & Function 

Daily leak testing is performed by Flo at a time when no water use is occurring. Realistically, this daily check doesn’t provide any more data than the real-time testing being done by the Phyn system. Because the Phyn ultrasonic system takes constant data points, there is more real-time information available, and a more reliable system overall. Alerts arrive more quickly with Phyn, and the auto-shutoff has less lag.

Both devices have a “learning period” while they collect data on your home’s typical water usage patterns. After this learning period, the devices should know your water use patterns and be able to filter out false alarms. In testing, this feature never worked perfectly. With any whole-home monitoring system, false alarms will occur, and Flo and Phyn are no exception. Even as the machine learns your tendencies, there are always exceptions (like irrigation systems, filling a pool, or running a sprinkler) that will trick the AI. 

With whole-home monitoring, you really just need to accept that any ready-made, commercially available system will have blind spots. Unless you are capable of programming a system that is custom for your usage and your home, you have to take the good with the bad.

Perhaps the most underrated part of Flo and Phyn is the water conservation information provided. Using these products, you may notice that someone in your house is taking long showers, leaving the sink running, or leaving a hose turned on. Having all this information available can empower you to change habits and conserve water. Some users have mentioned that the app data has allowed them to make a “game” out of saving water. In fact, Flo by Moen even provides water usage goals.

Final Thoughts

Both Flo by Moen and Phyn Plus are well designed yet imperfect smart water monitors and shutoff valves. At their current level of sophistication, both provide a great deal of value, but neither is a “set it and forget it” device that can totally ensure your house sustains no water damage.

These devices have the capability to alert you to a leak that could be costing you tens (or hundreds) of dollars per month on your water bill. And both Flo by Moen and Phyn Plus have allowed many homeowners to avert severe water damage. 

Because these smart water shutoffs can save you money, and help prevent disasters, we wholeheartedly recommend installing either Flo or Phyn in your home. However, you should understand that these are not 100% assurance that your house will be spared from water damage.