You can always recognise a failed unit because you will see condensation on the inside, between the 2 panes of glass. Many companies will replace the complete frame and glass units unnecessarily, you may only need to replace the failed glass unit.
Other issues can become apparent such as, a reduction in the soundproofing of your home and less thermal insulation. If this is the situation you find yourself in, then you may not require the entire window to be replaced.
We can visit your property to inspect your windows and advise if you only require the glass units, our honesty will save you time and money. If you do require full unit replacement however, we replace units in uPVC, aluminium and timber frames.