Most Newark calls start with three facts: what the boiler is doing, where it lives, and who owns it. A campus-area rental gas unit that locks out gets ignition questions plus maintenance-history questions (when was it last serviced — the answer is often "unknown"); a College Park colonial gas unit that fires then cuts out gets flame-sensing questions; a Cherry Hill sealed system losing pressure gets expansion-tank questions. The symptom plus the building's story usually identifies the subsystem before anyone travels.
On site, the technician tests within that subsystem — flame rectification current, igniter condition, gas valve operation with instruments, not by swapping parts — and explains findings before any work is authorized. Owners hear the diagnosis and decide; tenants hear it and relay it to the landlord with professional backing.