LOW SIGHTLINE SEALED UNITS

By using a new concept in the construction of double glazed units we are able to supply low sightline sealed units.

This is done by using the latest equipment and components that are available which allow us to have very small cavities or space between the glasses with a 5mm perimeter sealant depth. We also manufacture the low sightline sealed units using inert gases, this helps to reduce the centre-pane 'U' value of the units which subsequently helps to conform to building regulations.

Windowright low sightline Double Glazed Units use a combination of a 4mm clear outer pane with a choice of cavities of either, 3.9mm, 4.8 mm or 6.4mm using a warm edge super spacer bar. The warm edge bar is available in various colours, the 3.9mm only being available in white and all the other thicknesses are available in black, Charcoal, White, Gold and Light Grey.

If the value of the insulation provided by the sealed unit is a key factor then the wider the cavity the better the insulation, using an inert gas with a 4mm Low Emissivity glass will also help the insulation value of the low sightline sealed unit.

The low sightline units are particularly useful when completing Conservation projects and timber windows

Low Sightline sealed units will fit almost any suitable window rebate and are popular for conservation work or sash and casement timber windows.

• STANDARD CAVITY WIDTHS - 3.9mm - 4.8mm - 6.4mm (overall tolerances + or -1mm)
• MINIMUM TIMBER REBATE DEPTH/UPSTAND - 7mm - 9mm
• MINIMUM TIMBER REBATE WIDTH/CAVITY- 20/21mm (standard cavity 4.0mm)

Examples.....

Glazing
Allowing a maximum of 2mm between back of rebate depth and unit.

Sizes
Glazing sizes should be hard size of opening less 2mm from height and 2mm from width and allowances made for any irregularity in height or width.

U Values.

The insulation of double glazed sealed units are measured in 'U' Values, the lower the 'U' value figure the better the insulation. Below is a list of 'U' values that can be achieved when using certain components.

                                                                                                  Argon      Krypton      Xenon

Pilks 'K' or Low 'E'

4mm Clear / 3.9mm Warm Edge Spacer / 4mm low emissivity          2.7             2.2         1.8

4mm Clear / 4.8mm Warm Edge Spacer / 4mm low emissivity          2.5             1.9            1.6

4mm Clear / 6.4mm Warm Edge Spacer / 4mm low emissivity          2.2             1.7            1.4

Climaguard A or Planitherm Total +

4mm Clear / 3.9mm Warm Edge Spacer / 4mm Soft Coat                 2.6             2.0         1.6

4mm Clear / 4.8mm Warm Edge Spacer / 4mm Soft Coat                 2.3             1.7            1.4

4mm Clear / 6.4mm Warm Edge Spacer / 4mm Soft Coat                 2.0             1.5            1.1

Glazing Information for Double Glazed Sealed units into Timber Frames

Your low sightline double glazed sealed unit is manufactured to a high standard using top quality materials to EN1279 requirements. Our units are guaranteed as long as they are glazed correctly. Below are some principles that have to be considered when glazing sealed units into timber frames.

General Principles of Glazing.

The following points need to be followed to ensure the correct glazing of double glazed sealed units.

•  Prevention of prolonged contact of moisture with the edge seal of the sealed units.
   

• Compatibility between the edge seal of the unit and the glazing materials.
   

• Protection of the edge seal of the unit against sunlight  

Moisture Attack.

If water is trapped against the edge seal of a unit for a long period, failure of the adhesive bond of the sealant to the glass will result causing the unit to break-down. Moisture can penetrate to the rebate area, either through or around the glazing system, or through frame joints into the glazing system, from a variety of sources such as rainwater, window cleaning, condensation within frame sections and condensation on the room side glass surfaces. All glazing systems must protect the edge seal of the unit, either by preventing access of water to the seal, or by ensuring that water which penetrates as far as the seal, is soon removed by drainage of the rebate area by means of a specially designed frame.

Compatibility of Unit edge seal with glazing materials.

The edge seals of a unit have different compatibilities with different glazing materials. The hot-melt edge sealant used in Sealed Unit manufacture is not compatible with solvents, and because certain glazing compounds contain such solvents we recommend a good quality Low modulus Neutral Cure silicone sealant or a Security Glazing Strip such as Flexistrip.

Exposure to sunlight.

The edge seal on most units will degrade if exposed to ultra-violet light rays for a long period. It is essential, therefore that the rebates provide full cover of the edge seal from sunlight. It is normal practice for the spacer bar not to protrude past the rebate.