Work Performed: Attended call for wall-hung Lochinvar combination boiler (domestic hot water + radiant floor heating). Found system not providing hot water for both space heating and domestic use. Observed error codes: domestic hot water sensor and combi sensor. Inspected wiring connections, cleaned dirty contacts, and tightened all connections. Performed full maintenance and inspection of the boiler. Reset system and confirmed partial operation restored. Contacted Lochinvar tech support for further diagnostics and reviewed sensor readings with them. Results: Issue traced to a faulty inlet sensor, which is reading excessively high and preventing the boiler from initiating. Boiler restarted and temporarily functional after cycling power, but inlet sensor requires replacement. Recommended proactive replacement of both the inlet sensor and high-limit outlet domestic hot water sensor due to system age (2016). Advised client that parts may need to be ordered in. If boiler stops again, cycli