Customers oil boiler would not reset, heard loud buzzing noise when power turned on, aquastat relay was buzzing loudly tapped on relay and boiler started, turned power off and repeated tapped relay and boiler came one, aquastat relay is no good, replaced aquastat and tested, cycled boiler 5 times and let run until got up to temperature, circulator running for heat for one apartment that was calling and hot water, did let customer know of some possible items that may start to leak due to rust and age emailed estimate to customer. We bill this customer. System operational and working.