Making a Stove Glass Template
If you are unable to take an accurate measurement from your broken glass pieces or you no longer have the glass, or even if you don't know the stove make or model, then you can always make a template and determine the precise measurements for the replacement from that.
1 Use a penetrating or releasing oil to help free-up the glass clip retaining screws as these are bound to be very tight. Be very careful not to damage these as you will need to re-use them. To avoid damaging the screw heads be sure to use the correct allen key or screwdriver type and size.
2 For the height: Once the screws have been removed, take precise measurements (in millimetres) between the inside edges of a vertical pair of screw holes (see diagram). This should give you the maximum height of the glass. As you will need to allow for any expansion and movement of the glass and door frame, subtract 6mm from this maximum dimension to obtain the cut height of the glass. For example, if the height between screw hole edges is 300mm, take away 6mm tolerance, which gives you 294mm for the cut glass height. This should allow the replacement glass to overlap most of the gasket so that as much of the gasket as possible is in contact with the glass to maintain an airtight seal.
3 For the width: On many makes of stoves there are no retaining clips at the sides of the glass so you will need to take your measurement between the outer edges of the existing gasket tape at the sides and, providing there are no obstructions or channels on the door frame, add 4mm to that dimension to allow the replacement glass to overlap and make contact with as much of the gasket as possible in order to maintain an airtight seal. For example, if the width between the edges of the gasket is 400mm, then add 4mm for the overlap, which will give you 404mm for the cut glass width.
4 Use these cut glass measurements to make a card template, ensuring that the edges are straight and that the corners are at right angles. Use stiff card (so that it doesn't flex much) but that is still easy to cut.
5 Position the card exactly where the replacement glass will eventually be fitted. Check that the screws and retaining clips can all be returned without snagging the template. The template should cover all of the gasket and still provide 2 or 3mm of tolerance between the screws that retain the top and bottom clips. Importantly the template should completely cover the window aperture so that there are no potential air gaps. (see figure 4)
6 You may need to sightly adjust the template size to ensure that the height allows for some tolerance between the screws when the clips are in position and that the width overlaps the gasket edges without snagging on any casting channels etc. You will probably find that once you have produced and fitted your template that in reality the tolerances are not that critical. Use the final template measurements to obtain your quote and / or to place your order.
7 Do not dispose of the broken glass parts until you have received the replacement, so that it can be cross-checked against it. When you do eventually dispose of the broken glass remember it must NOT be placed with recycled glass, but must be regarded as non-recyclable material. See here.
Making a template for shaped or arched glass
If you know your stove make and model and it appears on the Stove Spare Parts list then, of course, you will not need to produce a template for us. However, if you need to make a template for an arched or shaped replacement then this guidance may help. If possible, piece the broken parts on some plain paper or card to recreate the original shape. Tape the parts together so that they do not move when you trace around them, being as accurate as possible. Provide any measurements in millimetres for the overall width, the overall height in the middle and the height of the the straight sides up to the point where they meet the curve of the arch. Cut the template out, using a steel rule for the straight edges. Check this against the door frame to ensure a good fit. In particular, check that the template covers most of the glass gasket and that any glass retaining clips can grip the glass, but also allow 2 or 3 mm tolerance against the retaining clip screws for the expansion of the glass and components. Post the template to us so that we can then provide you with an accurate price for cutting the replacement stove glass to match your template.
If you no longer have the shaped glass
If the glass is missing or it so badly broken that you are unable to trace around it then you should still be able to make a template, but it will most likely take a bit of trial and error. If the glass gasket remains in place on the door or alternatively there is a shaped channel for positioning the glass then this is a good starting point. Produce a first paper template by following the outer shape of the gasket (or follow the inside of the shaped channel) ensuring that you allow enough of the template to be gripped by the glass retaining clips. Cut the template out and check it against the aperture ensuring that any glass retaining clips can grip the glass, but that the template also allows 2 or 3mm gap against the retaining clip screws and any shaped frame to allow for expansion of the glass and components. Provided that the template can be safely retained with a good grip, that it covers all of the glass gasket to ensure an airtight seal and that, importantly, it completely covers the open aperture, then this should be good enough to proceed with your order. Ensure that all of the straight edges of the template have been cut with a straight edge, that the corners are at right angles and that the curved or arched part of the template is as accurate as you can make it and that any dimensions in millimetres are added to the template (eg overall width, overall height from the centre and the height of the sides up to where it meets the curve or arch). Post the template to us so that we can then provide you with an accurate price for cutting the replacement stove glass to match your template.