Which type of pipe is commonly used for 90+ condensing units?

The use of PVC schedule 40 pipe for 90+ condensing units is primarily due to its suitability for handling the acidic condensate produced by high-efficiency gas appliances. These units operate at higher efficiencies and typically produce a larger volume of condensate that is slightly acidic because of the combustion process. PVC pipe is resistant to corrosion and is ideal for draining the acidic condensate safely. This type of pipe is lightweight, easy to work with, and can be easily joined without the need for special tools or fittings, making it a practical choice for installation.

In addition, PVC schedule 40 pipe is specifically rated for the pressures and temperatures typically encountered in venting and draining applications for condensing appliances. This ensures durability and safety over time. Other materials like steel, copper, and aluminum may not offer the same level of corrosion resistance or may require additional protective coatings when used in similar applications. Hence, PVC schedule 40 pipe stands out as the most appropriate choice for these systems.