How to Install a SimpliSafe Entry Sensor on a Double-Hung Window

Overview

Double-hung windows have two movable sashes, which changes how an entry sensor aligns. This guide covers sensor and magnet placement, surface prep, angle limits, and testing so the sensor triggers reliably on lower sash opens.

Why This Happens in Real Homes

Double-hung windows have two movable sashes, which changes how an entry sensor aligns. This guide covers sensor and magnet placement, surface prep, angle limits, and testing so the sensor triggers reliably on lower sash opens. In day-to-day use, this usually looks like Existing SimpliSafe system online; Window frame is clean and dry; Double-hung window with two sashes.

Most cases trace back to Gap between sensor and magnet too wide; Adhesive pressed on dusty surface; Sensor oriented parallel to wrong sash. The fix works best when you go step by step instead of changing multiple settings at once.

A practical order for this issue is: Plan Placement -> Clean Surfaces -> Attach Sensor and Magnet -> Pair to Base Station. After each step, test the exact behavior that was failing so you can confirm what actually solved it.

What's Included

• Existing SimpliSafe system online
• Window frame is clean and dry
• Double-hung window with two sashes
• Entry sensor and magnet in hand
• SimpliSafe app installed
• Mild temperature for adhesive curing

Got your materials ready? Here's what to check first.

Before You Start

• Gap between sensor and magnet too wide
• Adhesive pressed on dusty surface
• Sensor oriented parallel to wrong sash
• Reed switch not aligned with magnet
• Cold temperatures weaken first bond
• Test triggered before system in alarm mode

Tools & Requirements

Installation Steps

1

Plan Placement

Attach the sensor to the stationary window frame beside the lower sash. Attach the magnet to the top edge of the movable lower sash. This orientation detects the sash rising during an intrusion attempt. Skipping this planning leads to sensors that fail to detect opens.

2

Clean Surfaces

Use isopropyl alcohol and a soft cloth to clean both the frame and sash where adhesive will sit. Dust and oils keep the included 3M adhesive from bonding fully. Allow to dry for a minute before peeling the adhesive backing on either the sensor or magnet.

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3

Attach Sensor and Magnet

Peel adhesive on the sensor and firmly press onto the frame for 30 seconds. Attach the magnet to the lower sash with dots facing dots. Ensure the gap between sensor and magnet is less than 1 inch when the sash is fully closed to guarantee reliable triggering.

4

Pair to Base Station

Open the SimpliSafe app, tap Add Device, and select Entry Sensor. Follow pairing prompts. Rename the sensor to match the window location, such as Office Window. Clear naming helps during alarm events when you need to know exactly which window triggered.

5

Test in Test Mode

Place the system in test mode from the app. Open the lower sash at least four inches. The sensor should beep or show open in the app. Close and confirm closed reading. If the sensor does not trigger, recheck magnet alignment and the sash-to-frame gap.

Installation Tips

Still stuck? This is usually the deeper cause below.

Need More Help? SimpliSafe Support

Note: The contact information below connects you directly to SimpliSafe's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.

How Does SimpliSafe Compare?

Before replacing your SimpliSafe device, see how it stacks up against alternatives in our full comparison guides.