In 1996 it became a legal requirement for Landlords to ensure that any rental property has a Landlord Gas Safety Certificate carried out annually, on all gas appliances. Landlords must ensure that all gas appliances and flues fitted in any property have an annual landlord gas safety check by a gas safe registered engineer. At the end of 2014, R-22 refrigerant will be banned under EU legislation. So air conditioner systems with R-22 gas will effectively become redundant as any loss of gas cannot be replaced. It is estimated that there are still millions of R-22 systems still in operation, but the main reason for businesses delaying implementation of R-22 replacement systems is, putting it simply, the expense.