When designing an HVAC condensate recovery system, key considerations include the type and size of the condensate storage tank, the piping and pumping system, and the treatment and filtration requirements for the recovered water. Additionally, the system must be designed to handle the volume and flow rate of the condensate, as well as any potential contaminants or debris. It is also important to ensure that the system is compatible with the existing HVAC infrastructure and meets local plumbing and water reuse regulations.