Crestline Mechanical Plans / SMACNA

Crestline Mechanical Plans / IMC 401.4

Generator room exhaust must terminate a minimum of 10 feet above grade per the Crestline mechanical plans. At 8 feet, exhaust fumes containing carbon monoxide and diesel particulates are too close to pedestrian level and can be drawn into adjacent building openings.

Crestline Mechanical Plans / IMC 505

The range hood is underperforming by 70 CFM (26% below design). At 200 CFM, the hood does not provide adequate capture velocity at the cooking surface — grease-laden air and cooking fumes will escape the hood and spread through the unit. Common causes include undersized ductwork, excessive duct length, too many elbows, or a damper not fully open. The exhaust system must be corrected to deliver the full 270 CFM specified on the plans. Inadequate kitchen exhaust also affects the makeup air balance — the 300 CFM makeup air shaft will over-pressurize the kitchen if exhaust is only 200 CFM.

Crestline Mechanical Plans / NFPA 37

The exhaust height is 2 feet below the minimum requirement. Per the Crestline mechanical plans (with engine-exhaust termination governed by NFPA 37), generator room exhaust must terminate a minimum of 10 feet above grade. At 8 feet, the exhaust outlet is only slightly above head height — carbon monoxide and diesel particulates from the generator exhaust could affect pedestrians, maintenance workers, or be drawn into nearby building openings. The 12-foot distance from the property line meets the 10-foot minimum requirement, but the height must be corrected by raising the exhaust stack an additional 2 feet to reach the 10-foot minimum.

Crestline Mechanical Specification

Wrong insulation type. While the thickness (0.5 inch) meets the minimum, mineral wool (PI-A) is unacceptable for refrigerant suction lines. The spec requires PI-B (elastomeric/rubber) because refrigerant suction lines operate below the dew point and will condense moisture from the surrounding air. Elastomeric insulation is closed-cell and acts as its own vapor barrier, preventing moisture from reaching the cold pipe. Mineral wool is open-cell and would absorb moisture, lose its insulating value, and cause corrosion on the copper suction line. The wet, degraded insulation would also drip onto equipment and ceiling tiles below.

Crestline Mechanical Specification / ASTM C1136

PVC jacketing is not permitted on outdoor pipe insulation per Crestline specifications. PVC degrades under UV exposure, becomes brittle, and cracks, allowing moisture infiltration that destroys the insulation. Aluminum or stainless steel jacketing is required for outdoor applications.

Crestline Mechanical Specification / California T-24

This installation meets code. In Climate Zone 3, the minimum R-value for supply and return ducts located outside the building is R-8. The contractor correctly used DW-B insulation with a metal jacket, which is required for exterior duct applications to protect the insulation from weather, UV damage, and physical abuse. If this project were in Climate Zone 5 or higher, R-12 would be required instead of R-8.