Window mullion connectors – what is it?
Mullion connectors is an internal element of bracing in the window with several casements. The component is invisible to the naked eye, but it impacts window’s integrity and energy efficiency.
What does the mullion connectors represent, and why do the customers need to understand what kind of bracing is used in certain window systems? Let’s get to the bottom of the topic together with the specialists of the VivoTech company.
What exactly is the mullion connectors?
A mullion
Let’s define what a mullion is first. The mullion (splitter) is a lintel that divides a window into parts. It can be encountered in the windows with several casements. Due to structural features of windows, the heaviest wind loads fall upon the mullion. Consequently, the mullion is the most quiescently loaded element of the window.
Mullion connectors
The mullion is attached to the window frame (profile) or casement with special bracing. This is what is called ‘mullion connectors’, or ‘heel’.
The mullion connectors is developed and produced for every profile system separately. Shape accuracy and milling predetermine solidity of abutting in the connection. Elimination of cracks guarantees ultimate energy efficiency of the structure, because in this section there is no possibility to replace the sealer, or to regulate it like the casement in the course of its service.
Types of mullion connectors
The mullion connectors are distinguished according to the material they are made of, and can be:
- Either metal,
- Or plastic.
How the metal connector outperforms the plastic one
The metal mullion connectors compared to the plastic can withstand the larger loads, and they don’t stretch, nor they produce cracks.
Some advantages of the metal mullion connectors:
- • High rigidity
- • High durability
- • Resilience to temperature drops
- • Long-term service
- • Simple installation
In contrast to the metal mullion connectors, the plastic one doesn’t add rigidity to the connection of the mullion profile and casement, and that leads to drooping of the glazing unit. Such problem with the plastic connector leads to replacement of the whole PVC structure.
Volodymyr Shimanskiy, chairman of the board of directors of the ViVoTech company:: “Leaders of the global market of PVC profiles such as Veka, Gealan, KBE and others calculated wind loads for windows and doors made of their profiles only with the metal mullion connectors. In the product catalogues of these extrusion enterprises only the metal mullion connectors are available. Therefore, application of the plastic connectors compromises reliability of the whole structure. Application of the plastic bracing for mullions leads to development of cracks in the window frame, which reduce to zero energy efficiency of the whole window structure. Metal connection is more rigid than plastic, and it provides both energy efficiency and durability of the structure. To avoid formation of thermal bridge through the metal, and consequently frost penetration of the window, special sealers are used in the sections of connection of the mullion with the frame”.
Why the customer should be aware of the mullions bracing
Replacement of windows is due every 15-20 years, and requires significant investments. At the present time in Ukraine usual plastic windows are replaced with energy efficient. It is caused by high cost of utilities and necessity to save energy, as well as by uncomfortable conditions of living with poor heating.
The window is a complicated structure, and mullions bracing is one of the components affecting its energy efficiency. Experience shows that even if the window is made of energy efficient components, one little crack can jeopardize all the efforts intended to achieve energy efficiency.
Even such tiny and hardly visible element as the mullion connectors can become crucial in the process of window selection. Moreover, it is almost impossible to replace it without dismantling the whole window.
When buying a window, pay attention to the following components that directly impact its energy efficiency:
- Glazing – opt for triple-pane window more than 40 mm width with two energy efficient layers and filled with inert gas (argon, krypton).
- Type of spacer bar – ask your supplier for a warm edge spacer.
- Choose durable metal mullions connection if the windows have two or more glazing units.
- Method of installation – insist on the ‘warm’, or European method of installation according to the established national standards (ДСТУ).
Installation of the energy efficient window with all the accessories necessary to guarantee energy efficiency during its service life will lead to reduction of energy consumption of the premises, and will consequently cut the utilities expenses.
