If your oven door seal or oven door gasket is faulty, damaged or missing, your oven will take longer to heat up and cook your food. Not only is this frustrating, it's a waste of time, energy and money - oven door seals are designed to trap heat inside the oven, and if your isn't doing its job properly, you'll be using more electricity, Gas, diesel than necessary or even worse, your food won't be getting cooked. properly at all.