Double Hung Window Weather Seal System for Pressure Differential Management
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Solution Overview
Problem
Pressure differentials between the exterior and interior of buildings can compromise the effectiveness of window seals in double hung windows, allowing moisture to enter during rainstorms.
Innovation Solution
A weather seal system featuring a primary air-tight and water-proof seal between the sash and sill, combined with a secondary air-permeable seal that maintains exterior air pressure within a sill chamber, reducing the impact of pressure differentials and channeling moisture away from the primary seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary air-tight and water-proof seal is used between sash and sill, then moisture entry is prevented, but pressure differentials push water through the seal
Solution Approach 1:
The seal system is divided into two distinct seals: a primary seal (140) that forms an air-tight and water-proof barrier, and a secondary seal (142) that forms an air-permeable water barrier. This segmentation allows each seal to perform its specific function independently, with the secondary seal relieving pressure differentials that would otherwise compromise the primary seal's effectiveness.
Solution Approach 2:
The secondary seal acts as an intermediary element between the exterior environment and the primary seal. It allows air to pass through while blocking water, thereby equalizing air pressure in the sill chamber with exterior pressure and preventing pressure differentials from building up against the primary seal.
2Reliability
If seal height is increased to improve sealing, then moisture entry is reduced, but sill height must be maintained reduced
Solution Approach 1:
The sealing function is segmented into two separate seals with distinct heights and functions. The primary seal (140) provides the main air-tight and water-proof barrier, while the secondary seal (142) provides an additional water barrier that is air-permeable. This segmentation allows the system to achieve effective moisture protection without requiring an increased overall seal height, as each seal contributes differently to the overall performance.
Solution Approach 2:
Different portions of the seal system have different properties: the primary seal is designed to be air-tight and water-proof, while the secondary seal is designed to be air-permeable but water-resistant. This local differentiation of seal properties allows the system to maintain reduced sill height while still providing effective moisture protection through the combined action of the two seals with their specialized characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively prevents moisture entry while maintaining reduced sill height, meeting industry standards for window performance and reducing the effects of pressure differentials on the seal system.
Implementation Method 1
The secondary seal allows a chamber within the sill to have the same air pressure as the window exterior to reduce the effects of pressure differentials on the weather seal system
Data Source
AI summary
A window includes a weather seal system that employs two seals. The first seal is located towards an exterior surface of the window and forms an air-permeable water barrier between an active sash and a sill. The second seal is located towards an interior surface of the window and forms a substantially air-impermeable and water-impermeable barrier between the active sash and the sill.