From Double Glazing to uPVC Windows in Chessington | FAQ & Videos

Here at Pro Window Systems Ltd, we take every measure possible to achieve complete customer satisfaction. We recognise that clear, honest communication goes a long way to attaining this goal, so we have listed and answered some of our most frequently asked questions below. Whether you have queries regarding a new front door in Chessington, double glazing installations in Ashtead, the thermal qualities of uPVC windows in Cobham or the benefits of aluminium bi-fold doors in Dorking, we’ve tried to answer as many as possible below.


If we haven’t addressed your particular question below, please contact us on 0208 288 8893.

Frequently Asked Questions


Where are you based?


Our company is located in Chessington. We operate within a 15-mile radius of our hometown.


How much experience do you have?


Our team shares more than 100 years of trade and industry experience.


What is ‘Secure by Design’?


As a police-backed standard promoting products specially-designed to deter, or at least make life difficult for, would-be burglars, Secure by Design plays a vital role in improving household security.


To paraphrase the police themselves, Secured by Design concentrates on preventing crime at homes and commercial properties by raising the standards of associated products and applications.


The principles of Secure by Design have helped to reduce crime risk by as much as 75% through a combination of time-served techniques for the natural surveillance of defensible space with minimal standards of physical security.


Established in 1989, the Association of Chief Police Officers currently owns Secured by Design. They remain dedicated to providing new and effective designs for security features in new and refurbished homes, commercial spaces and car parks.


The window industry continues to design security products that meet these minimum standards. Only companies that reach these standards can use the SBD logo on their website, literature and products.


What kind of handles do you offer for a front door?


We offer lever/lever and split spindle handles.


The former comes as standard for any composite front door. If the door remains unlocked, it can be opened from the outside by pulling the handle. Lever/lever systems require property owners in Chessington, Epsom, Esher, Leatherhead and beyond to manually lock their door.


The latter provides a front door with a greater level of security. When a door with a split spindle handle closes, the centre latch isn’t released. This means the door cannot be opened from the outside by simply turning the handle. Homeowners will always require a key to gain entry. Options for handles include a rounded pad-shaped design or a straight lever on the outside, as well as a straight lever handle on the inside too.

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How do I toe and heel?


UPVC windows (sash) and doors hold a large amount of dead weight. The hinge side supports a significant amount of this load, but the lock side offers nothing in this regard. Without the process of toeing and heeling, the door or sash window will drop on the handle side.


To prevent this, we brace the door or glass panel diagonally from corner to corner by inserting plastic packers in the gaps between the panel and the frame.


The process begins by raising the door or uPVC windows (sash) squarely to the desired height on the lock side. Packers should be placed on the hinge side in the bottom corner. On the lock side, the packers must be placed in the opposing top corner. We recommend that homeowners in Chessington, Molesey, Oxshott, Surbiton and the surrounding areas dab some silicone under the packers to stop them from dropping.


The packers need to be placed around 150mm from the frame’s edge.


Why do I have condensation on my double glazing?


To understand why condensation appears on double glazing, we have to look at the different forms in which it occurs:


1. On the external face.

2. On the inner surfaces.

3. On the internal face.


In regard to the first point, surface condensation appears on the external face of glazing with a temperature markedly lower than the external air temperature. In addition, the dew point (the temperature at which water vapour transforms to liquid) of the external air also needs to be higher than the temperature of the glass.


The surface temperature on the outside of the double glazing depends on several factors. One such influence is the heat flow from the internal space of a home in Chessington or the neighbouring areas that passes through the glass. This, in turn, depends on the temperature difference between the interior and exterior surfaces, as well as the U-value of the glass itself. These both have an impact on the heat exchange by convection with the external air and heat loss through radiation to the sky.


With single glazing, the surface temperature rarely drops below that of the external air temperature, meaning condensation occurs inside rather than outside. With the improved thermal insulation qualities of double glazing, the transfer of heat to the external surfaces significantly reduces. As such, these outer surfaces remain colder and at a higher risk of condensation.


Importantly, this signifies good thermal insulation, not poor quality double glazing.


In regard to the second point, condensation forms on the inner face of double glazing when the seal of the gas or air cavity has been compromised. The desiccant quickly becomes saturated and any damp air that penetrates the perimeter seal forms condensation on the internal faces. In these circumstances, the double glazing unit must be replaced.


The breaking of a seal usually occurs due to a natural ageing process.


However, some temporary condensation occurs that doesn’t indicate the breaking of a seal. These situations include short spells of high humidity or exceptionally cold weather, during construction projects that use water-based materials and in temporarily confined spaces such as that between the double glazing and drawn curtains.


In regard to the third point, condensation on the internal face can be attributed to the following factors: external climate, internal air temperature, humidity within a building, ventilation flow rate and surface temperature of the glass.


To reduce condensation occurring, we advise controlling the above parameters, with the obvious exception of external climate. The most effective way to do this remains collecting water vapour at its source before removing it (as in bathrooms and kitchens). Adequate ventilation and heating also has a positive impact.

To discuss any queries you may have, from uPVC windows to aluminium bi-fold doors, regarding your home in Chessington or the Surrey area, call 0208 288 8893.

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