You’re welcome! The key mechanism for stopping drafts and winterizing plastic windows lies in adjusting the pressure of the window sash against the frame.

Many modern plastic windows have a mechanism that allows you to adjust the seal (the pressure) depending on the season. This is often referred to colloquially as “winter mode.”

Here are the step-by-step instructions for adjusting your window to keep it warm in winter:

Step 1: Find the leaks and fittings
Check for drafts: Perform the paper trick. Wedge a sheet of paper between the window sash and the frame and close the handle. If you can easily pull the paper out with the window closed, the pressure is too low and you’ll be drafty.
Locate the locking pin (mushroom or roller cam): Open the window sash. On the side where the handle is located, you will see small, round or oval metal pins (the locking pins) that engage with the fittings on the frame. These are the elements you use to adjust the contact pressure.
Step 2: Increase the contact pressure (winter mode)

Get your tools ready: You will usually need an Allen key (usually size 4 or 5 mm) or, depending on the window model, a screwdriver or small pair of pliers.
Adjust the pins: Each locking pin has a mark (often a line or a dot) or a slightly eccentric shape.
For winter (increased tightness): Turn the pin so that the mark points towards the window rubber (the seal). This shortens the distance to the frame, and the window sash presses more firmly against the seal.
Caution: Turn the pins only gradually and carefully. Excessive pressure can place unnecessary strain on the rubber seals and cause premature wear.

Step 3: Check function and readjust if necessary
Test: Close the window and check whether the handle is significantly harder to operate than before, but without excessive force.
Repeat the paper trick: The paper should now be difficult or impossible to pull out with the window closed.
Adjust evenly: Repeat the process on all locking pins of the window to ensure even pressure.
Additional tips for winter

Maintain seals: The rubber seals should be treated with a silicone spray or deer tallow before winter. This keeps them supple and prevents them from becoming brittle or freezing solid in frost.
Oil fittings: Apply a drop of resin-free oil to the moving parts (hinges and fittings) to maintain smooth operation.
Reset in spring: Remember to reduce the contact pressure slightly in summer (turn the pin away from the seal) to relieve pressure on the seals and allow for slight air circulation (micro-ventilation).