Fitting your mirror demister correctly is vital to ensure its trouble-free operation.

The mirror should be placed face down on a suitable flat surface, and the back of the mirror should be cleaned of any dust or grease.

You should remove the protective backing from the mirror heater and, placing it centrally in your mirror, you should place one edge of the heater onto the mirror and firmly press it onto the back of the mirror.

You should then work outwards from that point sticking the whole heated pad onto the back of the mirror while carefully smoothing away any air bubbles. Do not worry if there are white patches that form beneath the film as you fit it, this is due to a de-lamination between the internal layers of the pad and does not affect the heater's performance.

In general, we advise against fitting demisters to mirrors with cut-outs for lights or shaver sockets as these can weaken the mirror. If you are looking to heat these types of mirror, we recommend an unheated gap of at least 200mm between the cut out and the demister.

You should not fit a demister onto a mirror that has any damage, and we do not recommend fitting mirror heaters to antique mirrors as there is no way to check if they are suitable for direct heating.

The final electrical connections must be made by a suitably qualified electrician and should comply with the latest wiring regulations. Usually, the Demista pad would be powered through the lighting circuit so that it energises whenever the bathroom light is activated, although the heater can be wired through a separate switch or on a timer if preferred.

Any circuit supplying a 230V mirror demister must be protected by a 30mA RCD or equivalent and must also be protected by a suitably rated MCB. The power rating of all Demista brand mirror demisters is 200W/sqm.

12V and 24V Demista mirror heaters can be installed outside of Zone 1 when using a suitably rated and approved low-Voltage transformer. When installed in Zone 1 a suitable SELV isolating transformer must be used, with the transformer being installed outside of Zone 1.

For large or unusually shaped mirrors multiple heaters can be fitted to a single mirror, and these must be powered in parallel; if fitting low-Voltage pads they can be run off a single transformer if it is suitably rated for the combined load.

When fitting multiple pads together on a single mirror it is important that they do not overlap, and we recommend an unheated area at least 10mm wide between the heaters.

The mirror defoggers are supplied with a 1.0m double-insulated supply cable which cannot be lengthened or replaced. If this supply cable is not long enough for your requirements a suitable junction box should be used to bring the power to the mirror heater.

Once the mirror heater has been installed it must not be accessible or in an area where it could be physically damaged. All exposed metal parts surrounding the mirror (for example if the mirror has a metal frame) must be earthed to comply with the current wiring regulations.

Mirrors that have a foil backing or metallic covering must be earthed using a grounding pad to remove the risk of a capacitance build up.

The wall area where you are going to fit your mirror should be firm, flat, and dry, and the mirror must have space at its edges to allow it to expand slightly as it is heated.

If using a mirror adhesive this must be solvent and acrylic free, and we recommend adhering to the adhesive manufacturer’s instructions. It is perfectly acceptable to use mirror adhesive on the back of the heating pad.

If the mirror is being fitted to the wall with screws, the screw holes must have bevelled edges, and the screws must not be over tightened as this risks cracking the mirror. The screws must be isolated from the mirror with a material such as cork or rubber which will allow slight expansion.