Hot Water Boiler.( light comercial unit) Perform a tune-up and cleaning to help ensure reliable and safe operation. Inspect for cracks & deterioration of Heat Exchanger. Check and clean Burners, brush and vacuumed-ok Check and clean flame sensor and ignition Assembly-ok Check Safety Controls-ok Check low water cut off- secondary LWCO no connect to the boiler. Check electrical wiring and components-ok Check water feeder-ok Check back flow prevent-ok Check expansion tank-ok Check relive valve-ok Check x2 Gas valve & Gas Line-ok Check Combustion Air, Flue pipe-ok Check Temperatures & Water pressure settings; Performance-ok Check and run Thermostats-okay Check circulation pumps-ok Perform inspection on a HWH. Check for water leak, no leakage at this moment. Check gas valve-ok Check gas line-ok Check combustion and flue pipe -okay Run and monitored for good operation-ok Run system, check radiators, all of them getting hot, left system operating well at this moment. notes: A new tstat