[Snowman]

Great thread, glad you have all participated and I thank you. What a great year to be looking at a project like this when coroplast is such an abundant upcycle resource.

My home is circa 1950's and 1400 sq.ft, located in New Hampshire USA. As such I have "need" for summer A/C for a few weeks (3-4) and a month on either side where I would like some stretch of the A/C dehumidification, especially of the overnight air to keep the house cool but dry and comfortable. Then the spring and fall allow open windows and doors all day and night. But the winter is 3+ months of being shut in where some fresh air is needed. I want to build an HRV for both the summer A/C and dehumidification seasons as well as heating season to optimize fresh air with heat exchange. Bonus for cooking, bathroom and laundry extraction and filtered fresh air even during times of reduced "need" and bypassing the HX cores with increased venting and fans.

My conceptual design after reading this thread is a thin quad core cross flow design using coroplast to ease construction and optimize efficiency as a pseudo counterflow HX. I also think it would be easily cleanable and minimize freezing due to the long condensing path, enabling more water extraction prior to icing. I'm planning 12"x12" cells stacked 6-8" thick with the "spacing" design; balancing the "open" and "restricted" airflow paths to equalize flow restriction across the core(s) and put the "open" paths in the condensing area to promote draining.

Phase 1: Build cores and housing with 2" foil lined rigid foam and plumb insulated lines for supply and return to the interior and exterior.
Phase 2: Upgrade fan controls with T/RH feedback and web interface for control of PWM.

Further upgrades or options to consider:
1. Automate HX core bypass for extraction and filter modes.
2. Evaporative misting in exhaust stream for intake cooling assistance.
3. Integration of thermal mass or zeolite.

I'm having fun and will update as progress is made.