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Testing Smart Automatic Water Shut Off Valves

Ask This Old House plumbing and heating expert Richard Trethewey tests two different styles of smart automatic water shutoff valves.

Steps for testing smart automatic water shutoff valves:

1. Kevin and Richard recap that any smart automatic water shutoff valve can both help prevent catastrophic bursts and minimize flood damage.

2. Right now, these devices generally fall under two schools of design:
a. Point Sensor Activated: Sensors are placed in “high risk areas,” like around a washing machine, under a water tank, etc. Sensors then connect remotely to a valve that’s installed near the main shutoff. When the sensors detect water, they communicate with the valve and tell it to shut off.
i. Pros: Fast response time once it detects a leak, and it can talk to a large number of sensors.
ii. Cons: If there are plumbing failures where there isn’t a sensor, it won’t work.
b. Valve Body Activated: The valve has components on the inside that allow it to measure the overall health and activity of the waterpipes, which varies from valve to valve. Most of these types of valves measure the flow rate of water, which helps them determine what fixtures are being used in the house. If the valve detects an excessive flow of water, it will shut the valve off.
i. Pros: All the smarts are in the shutoff valve itself, making it easier to keep track of than the system of components for point sensor valves, the information the valve collects can help it differentiate and improve water usage in the house, meaning it’s useful even when it’s not detecting plumbing failures, and the valve is not dependent on sensors “finding” the leaks. If there’s a plumbing failure anywhere in the system, it will close the valve.
ii. Cons: There’s a slightly slower response time than point sensor valves (because it’s so smart, it needs to “think” about whether this water is being used for something else or if it’s actually a plumbing failure, and it can trigger “false alarms” if a large amount of water is being used and the valve worries that it’s a flood.


Richard explained that most modern automatic water shutoff valves fall under two categories of design: sensor-activated and valve body activated.

The sensor-activated valves are usually more economical and have a faster response time, since their primary function is to detect leaks and other plumbing failures. The sensor-activated valve Richard demonstrated was a Floodmaster App-Based Wireless Plumbing Leak Detection & Automatic Water Shut-Off System, which is manufactured by Reliance Detection Technologies. The kit comes with two sensors and additional ones can be purchased and paired.

The valve body activated valves have more features to them, including usage reports and running health tests to try and catch plumbing failures ahead of time. The all-in-one smart valve Richard demonstrated was the Phyn Plus Smart Water Assistant + Shutoff, which is manufactured by Phyn.

Expert assistance with this segment was provided by the Walter F. Morris Company.

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