The picture shows an old Raypak boiler, inside the cabinet I observed white particles in the area of the burners and heat exchanger in addition to rust particles. There is also a long vent connector from the boiler to the B vent. The water heater, conventional draft and a gas fireplace vent connector are connected to the boiler vent connector. Here are some concerns that I noted to my client, no visible support for the boiler and fireplace vent connectors, the length of run of the boiler vent connector to the B vent is considerable and poses a possible fire hazard. The B vent should have been installed as close as possible to the boiler draft hood and has the chimney been sized properly for the 3 gas fired appliances. Back drafting ( CO ) is the implication for improper chimney sizing. I suggested the client call a licensed HVAC technician for inspection.