If you’re in the U.S. you may even be able to get a free (or at a substantial discount) commercial heat exchanger later this year: https://www.hvac.com/resources/inflation-reduction-act-heat-pump-rebates/ Not quite as fun as the DIY version though!
Even more DIY: https://ecorenovator.org/forum/showthread.php?t=891&page=38#post27793
If you’re in the U.S. you may even be able to get a free (or at a substantial discount) commercial heat exchanger later this year: https://www.hvac.com/resources/inflation-reduction-act-heat-pump-rebates/ Not quite as fun as the DIY version though!
Even more DIY: https://ecorenovator.org/forum/showthread.php?t=891&page=38#post27793