Installed a new Viessmann combi boiler, including all new venting, boiler piping, and required electrical connections, and tied the unit into the existing heating system piping. Filled the system with approximately 20 gallons of glycol and thoroughly purged all heating zones to remove air. During purging and system startup, it was determined that approximately half of Zone 3 was not heating properly and is suspected to be frozen; this condition was communicated to the customer at the time of service. The boiler was commissioned and set with a space-heating setpoint of 180°F, and the domestic hot water mixing temperature was adjusted to 135°F with the mixing valve set at 4.5. A complete system walkthrough and operational overview was provided to the customer, and the boiler and heating system were tested and confirmed to be operating properly at the completion of the installation
