Aways and without, fail every 12 months. Commercial boilers are susceptible to wear and tear given their heavy duty use. From a guarantee/warranty viewpoint an annual service is mandatory and shows due care and attention have been demonstrated to ensure the boiler is running efficiently. If the boiler has not been serviced annually (whilst under warranty) and there is a breakdown, the business owner could be responsible for the cost of the repair. Therefore, make sure your annual servicing records are up to date and run continuously to avoid paying for what might be an expensive repair!