Installed a new Viessmann boiler and corrected the exterior venting to improve system reliability, efficiency, and safe operation. Connected to existing heating and electrical systems. Purged boiler free of air. Performed 3 minute gas leak check at 8 inches of water column. Performed combustion test of boiler and confirmed proper operation of boiler. Installed a Rinnai on-demand propane water heater flowed water through existing indirect tank to ensure tank stays flushed. Installed bypass valves to make on demand water heater the prime source for hot water.