Double Glazing

Double Glazed Sealed Units

CN Glass manufacture Double Glazed Units by hand to British Standards BS EN1279 Parts 2 & 3.

A skilled workforce in traditional glass and glazing techniques working with the most up to date machinery providing high quality hand finished products for our customers.

The annealed glass is cut for production on our Automatic cutting bench then passed through our toughening plant where required before then taking the journey through the unit assembly line and finally the units are sealed by hand. In addition to this we also have a totally hand assembled and finished unit assembly line for our Heritage glass units, intended for period properties and timber frames.

We believe a hand finished double glazed glass unit produces a superior quality unit because each glass unit is constantly being monitored as it goes through manufacture and we are proud to put a 5 year guarantee on all our supply only double and triple glazed units subject to the glazing of the units also being carried out to British Standards BS 6262.

We guarantee our units for 10 years when we also carry out the installation of them into new frames.

Currently, we are producing an average of 500 units per day for delivery to our customers.

Double glazing repairs

If you’re suffering from misted double glazing or damaged windows, we can help. We offer comprehensive double glazing window repairs on your existing units by qualified engineers.

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  • Glass Tougheners
  • Manufacturers of Insulated Glass Units
  • Glaziers and Installers of Glazed Products

About our Double Glazed Sealed Units

Double Glazed Sealed Units are manufactured by us using either Aluminium Spacer Bar or Warm Edge Spacer Bar to provide the air gap between the two panes of glass. Eco-Slim Heritage Double Glazed Units

Super Spacer is produced down to a minimum depth of 4mm allowing us to produce the VERY THIN Double Glazed Units suitable for glazing in conservation areas and listed buildings (subject to planning permission). It is important to note that sometimes you do have to use Krypton/Xenon when limited width is available. i.e.: in old buildings for example.

Triple Glazed Sealed Units

At its most basic a Double-Glazed Unit will consist of two pieces of glass seperated by a spacer bar which denotes the thickness of the cavity. By using three panes of glass and two spacers we can make a Triple-Glazed unit. But to put things in context, a single-glazed window will have a U-value of 5.0W/m2, double-glazed will be between 2.2 and 1.2W/m2 and triple-glazed 1.0 to 0.6W/m2.

In a new build, installing double glazed windows is a must, but there is little point in triple-glazing unless you have super-insulated the rest of the house. Triple-glazing will cost about 20 per cent more than the standard double-glazing cost and reduce the overall heat loss by about 5 per cent.

Spacer Bar

ALUMINIUM SPACER BAR

spacer bar, sometimes known as a profile, is the continuous hollow Aluminium frame that separates the two glass panes in a double glazing window.

The spacer bar is bonded to the glass panes via a primary and secondary seal, creating an airtight cavity which is filled with air or gas. The spacer bar itself is filled with a desiccant to absorb any residual moisture within the cavity and thus prevent condensation within the double glazing window. Spacer bars are an important contributor to a double glazing window’s energy ratings. Aluminium spacer bars are currently the most commonly used in double glazing windows. Light but strong, their flexibility means that they can be formed into a wide variety of shapes and sizes. Less expensive than warm edge spacers they are, however, less effective in insulating against heat loss than warm edge spacer bars.

WARM EDGE SPACER BAR

Low E windows with the highest performing double glazing window energy ratings use a combination of Low E glass, warm edge spacers and argon gas-filled cavity.

Warm edge (or thermal break) spacers reduce the heat lost around the perimeter of a double glazed window unit by replacing conventional aluminium with a low heat-conductive material. As with aluminium, thermal break spacer bars are filled with a silicone desiccant to absorb any moisture within the double glazing window and can contain dry air or gas-filled cavities. Thermal break spacer bars further reduce condensation on the room-facing surface of the double glazing window as they transmit less of a temperature difference to the interior pane.

Warm edge spacer bars have the same geometrical form as a metal spacer bar, but are usually made from a fibre-glass reinforced insulation material. An ultra-thin foil lining acts as a barrier to the gas or air trapped within the cavity. Some warm edge spacers are available in an array of different colours.

edgetec super spacer

EDGETEC SUPER SPACER

Super Spacer introduces no-metal, pre-desiccated, structural foam spacer system that is a warm edge technology to suit all sealed glass unit applications helping to deliver windows of the highest standards. It offers a complete solution for Georgian Bars, simulated divided lights and astragal bar windows. Super Spacer is a flexible material that does not have to be cut and jointed by keys (elbo joints) to form shapes.

Its award winning, patented Thermal Set Spacer (TSS) technology gives the ultimate in high performance spacer systems. Super Spacer has 100% memory and allows for expansion and contraction, a major cause of fractures in conventional sealed units.

Most PVC-U and traditional timber windows include low line glazing beads and gaskets. This creates problems for standard aluminium spacer bars which protrude into the sightline of the window. Super Spacer has a lower sightline (equivalent to only 9.8mm from the edge of the glass) which eradicates the problem.

Super Spacer also takes on the appearance of the colour of the profile into which it is glazed. For example, if Super Spacer is glazed into white profile the spacer reflects back white.

Argon – Krypton – Xenon

The introduction of gas into the cavity of a double glazed unit reduces the heat conductance between the panes, helping to keep more heat in during the winter and out in the summer. As a result living and working conditions become more comfortable the whole year round. The combination of Argon Gas and Low E energy saving glass can achieve an improvement in thermal performance in the region of 50% over and above that of a standard sealed unit.

Argon, which has 34% lower thermal conductivity than air, is the most commonly used. Apart from its heat insulation properties, Argon is non-toxic, sunlight stable, non corrosive, colourless and odourless.

Although argon-filled units cost around 5% more than air-filled units, they can improve a double glazing window’s U value or energy rating by over 30%. Argon fillings should last the lifetime of a double glazing window and over a period of 25 years should not lose more than 5%.

Krypton and Xenon are even more energy efficient than Argon but are seldom used in double glazing windows as they are more expensive.

It is important to note that sometimes you do have to use Krypton/Xenon when limited width is available. i.e.: in old buildings for example.

Eco-Slim Heritage Double Glazed Units

Super Spacer is produced down to a minimum depth of 4mm allowing us to produce the VERY THIN Double Glazed Units suitable for glazing in conservation areas and listed buildings (subject to planning permission).

Heritage Slim Leaflet download

The thickness of our double glazed units can vary depending on the project requirements.

Please call our friendly team on 01295 263364for help finding the right fit for your project.

The thickness of a normal double glazed sealed unit can vary in size depending on the frame. The table below shows a list of the thicknesses available:

Overall Depth Glass x Spacer Bar x Glass
• 14mm (4-6-4)
• 16mm (4-8-4)
• 18mm (4-10-4)
• 20mm (4-12-4)
• 22mm (4-14-4)
• 24mm (4-16-4)
• 28mm (4-20-4)

A 20mm spacer is the widest available, so using 4mm glass the widest unit will be 28mm which is used as standard in all our PVCu and Aluminium windows and doors, with thinner units more commonly used in timber frames.

Most of the older timber frames tend to accommodate 14mm or 16mm units, with the newer timber frames (complying with the building regulations part L) typically being 20mm – 24mm.

Most sealed units we make now have ‘Low E’ glass to meet current building regulations and are 20mm or thicker.

Glass is a good insulator but it would need to be very thick as a single pane in a window to have much effect.
So rather than have thick glass in your windows it is better to have two panes of glass with an air or gas space between them. The bigger the air space, the less heat is lost, up to an optimum of 20mm.
All well designed and well fitted double glazed units significantly reduce the intrusion of unwanted noise.
By specifying glasses whose thickness differ by at least 30%, resonance effects are suppressed and the acoustic benefits are, therefore, maximized.

What are the benefits of having Double Glazed Units?

  • Heat loss through single glazing will be at least halved with double glazed units
  • Draughts through windows caused by sinking cooled air will be less with double glazed units
  • Rooms will be warmer with double glazed units
  • Outside noise can be reduced with double glazed units
  • Condensation can be reduced with double glazed units
  • Increases the saleability of the property with double glazed units
  • Savings on fuel bills with double glazed units

CONTACT CN GLASS TODAY TO ARRANGE A QUOTATION