1 Gas Hot Water Boiler: Navien Hi Eff Combi Boiler Perform a tune-up and cleaning to help ensure reliable and safe operation. Inspect for cracks & deterioration of Heat Exchanger Check and clean - ok, Check and clean flame sensor/flame rod and ignition Assembly-ok Spark igniter. Check Safety Controls-ok Check electrical wiring and components-ok Check Gas valve & Gas Line-ok Check Combustion Air & Exhaust-ok Check Temperatures & Water pressure settings; 19.4psi Performance-ok Check and run Thermostats- operating well at this time. Check circulator pumps-ok amps and voltage check. Check water feeder, low water cut off, and expansion tank. Check for water leak no leakage at this moment. Run and monitored for good operations. All zones are fine supply and return lines getting hot. Perform check for water leak, no leakage at this time. Recommending to customer to replace Neutralizer stones. Customer did not want to move forward @ this time. Customer will supply their own neutralizer stone.