Upon arrival met customer plumber who was on site prior to my arrival. Customer informed me that he was here for similar issue of noise/smell complaints. Plumber verified that issue is with HWH. Spoke with customer via phone. Customer requested for boiler to be checked for normal operation. Proceed to inspect boiler. Notice plumber may have put power back to boiler and checked operation. Found boiler on and running with 1st floor Unico system. Check operation once more. Cycle boiler on/off, boiler satisfied and shut down normally, saw burn tubes and undercarriage of boiler dirty. Recommending that customer follow up with heating maintenance for Weil McLain boiler w/x2 hydro AH System is normally operating @ this time. Not smelling anything while boiler is running. Issue is related to HWH not venting correctly. Boiler may share same chimney but boiler is not tripping on safety. Chimney Cleaning may have been recommended to customer by his plumber. Plumber is correcting issue with HWH fo