Step-by-Step Guide

Wiring Options for PFS-200 Flow Sensors on Conventional Wire Controllers

When installing a PFS-200 (plastic flow sensor, two-inch) with a conventional wire controller, you need to understand the wiring requirements and limitations. The PFS-200, like all baseline flow sensors, is a two-wire device designed to connect to a two-wire path through a flow encoder.

Can You Use Existing Number 14 Wire?

The short answer is no — do not use existing number 14 gauge wire to connect to the flow sensor, even if it's already in the ground and runs the path you need.

Number 14 wire and other conventional direct burial wire consists of a copper conductor with an outer jacket of either PVC or high-density polyethylene. This type of wire is a power cable, not a data cable.

Two-wire cable, by contrast, contains copper jacketed wire inside two conductors, but also includes an outer jacket of high-density polyethylene. This construction makes it a data cable, which is what's required for proper flow sensor communication.

While you might be able to make number 14 wire work in the short term, using conventional wire for a two-wire path will cause problems over time. The cable is not designed for the data transmission requirements of the flow sensor system.

Running Two-Wire on a Conventional Wire Controller

Even though the PFS-200 requires a two-wire connection and you have a conventional wire controller, you can still make this work without replacing your entire system.

Conventional wire controllers include both conventional wire terminal strips and dedicated two-wire terminals. You'll find a red terminal and a black terminal specifically for connecting two-wire paths.

1. Run a dedicated two-wire path from the controller's two-wire terminals (red and black) out to the flow sensor location.

2. Ensure the two-wire cable meets baseline specifications for proper performance.

3. Continue using conventional wire for all other station connections on the controller.

This hybrid approach allows you to add flow sensing capability to a conventional wire system without rewiring your entire irrigation setup.

Understanding the "Flow Contacts Triggered" Error Message

The error message "Flow contacts triggered, all watering has stopped, value equals open" indicates that the controller recognized a flow condition (whether it actually existed or not) and stopped all watering as a safety measure. This message appears as a bright orange error on the controller screen.

This specific error message indicates you're running a two-wire system, not a conventional wire system.

Locating the Source of Flow Contact Errors

The problem originates at the controller's two-wire path connection point, specifically with the jumper wires that connect various contact terminals.

Behind the jumper wires, you'll find labeled terminals for:

• Pause
• Rain
• Flow
• Common

Under normal operation, the pause terminal connects to common, the rain terminal connects to common, and the flow terminal connects to common through jumper wires.

Resolving Loose Flow Contact Jumpers

1. Loosen the screw terminals holding the jumper wires and remove the jumpers to access the labeled terminals behind them.

2. Identify the Flow terminal and the Common terminal.

3. Check that the wire is making full contact at both the flow screw terminal and the common terminal.

4. Use a screwdriver to tighten both screw terminals, ensuring they're snug and secure.

5. Reinstall the jumper wires and tighten them securely.

A loose connection at either the flow terminal or the common terminal will trigger the error message and stop all watering.

Rain Contact Switch Errors

Similar errors can occur with the rain contact switch. If you don't have a rain switch installed, the rain jumper terminal must remain in place and properly secured.

Rain jumper terminals are present on both two-wire controllers and conventional wire controllers. If the rain jumper becomes loosened, you'll receive a similar error message to the flow contact error.

Follow the same troubleshooting procedure: locate the rain jumper terminal, ensure the wire is making full contact, and tighten the screw terminal securely.

Importance of Jumper Wires

Flow contact jumpers and rain contact jumpers aren't used very often in modern installations, but they serve a critical function. These jumpers must remain in place and properly tightened at all times.

Problems typically occur when someone disconnects or removes the jumpers during maintenance or troubleshooting and either fails to reinstall them or doesn't tighten them back down completely. Always verify that jumper wires are present and secure when working on controller wiring.

Video Walkthrough

Video originally published April 2021.

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