The exhaust system shall be complete with flexible connections, exhaust piping, condensation trap with drain, exhaust silencer, support hardware, etc. The exhaust silencer shall be of the critical area type and shall be sized to prevent excessive backpressure. The silencer and exhaust piping shall be insulated and supported independently of the engine. The end of the exhaust pipe shall have a 45-degree miter and shall be provided with a bird screen. (Design Guideline DG-08 § 18.2.2, dated August 2006)