Cold gliding window: convection or outside-air leak?

Quick answer. A cold sensation near an Andersen gliding window does not by itself prove a failed weatherstrip. Andersen distinguishes convection—room air cooling near glazing and sinking—from infiltration through an outside air path. The first is a circulation effect; the second points toward the window or its wall/frame junction. ¹²

Two explanations, different investigations

This is a decision aid, not a quantitative infiltration test. A single household candle, tissue or incense observation is not evidence here of a conclusive diagnosis; that observation alone does not establish the cause.

A sequence that avoids unnecessary purchases

1. Get the gliding sash into its normal closed condition. Andersen recommends routine cleaning and checking that the sash is fully closed and locked before escalating a draft concern. ³ Record whether the sensation persists under that condition.

2. Look for actual condition evidence. In the manufacturer troubleshooting pathway, gaps, damage and permanent compression/flattening in gliding-window weatherstrip are reasons to investigate replacement. ⁴ Photograph the specific defect; do not invent a seal profile from how cold the glass feels.

3. Write down where the evidence is. Choose glass area, sash meeting rail, other sash edge, or wall/frame joint. The manufacturer explicitly separates an outdoor infiltration pathway from convection at a cool surface. ¹²

4. If it is a 200 Series center meeting edge, classify the part. Andersen's 200 Series check-rail source allows a bulb-only route for a damaged bulb but advises a stationary sash replacement when the rigid vinyl interlock is damaged. ⁵ The same source locates the check-rail assembly on the stationary sash's meeting side. ⁶

5. Keep unresolved cases unresolved. If closure, cleaning and visible seal checks do not identify an air path, document the conditions and seek an appropriate unit/installation assessment rather than ordering more weatherstrip by guesswork.

A three-line record to save

• Observed symptom: what feels cold, exact position, sash locked or unlocked, and photos.
• Visible physical evidence: gap, tear, flattening, frame junction condition, or none confirmed. ⁴
• Next action: no seal failure confirmed; specific sash component needs exact OEM check; or wall/frame issue needs assessment.

Do not use a flame test near fabric, do not perform destructive probing, and do not describe the result as a certified air-leak test. When no defect has been demonstrated, the safe conclusion is insufficient evidence for a weatherstrip order, not a diagnosis inferred from sensation alone.

Sources and references

All footnoted manufacturer facts were checked against the original publisher pages on 2026-10-11. A source describing a product family does not prove a specific unit or replacement fit.