Mike Jay wrote:Thanks Pearl, that's interesting. How big was his greenhouse?
I bought my heat exchanger on ebay - search ‘12x12 Water to Air Heat Exchanger’. I used the 12x12, but they have other sizes too. the 12x12 is rated at 50,000 BTU, 700 CFM and 6 GPM. These are the three things you will have to consider in choosing a size. First, how much heat you think you can harvest, what the air flow across the exchanger will be, and what your flow rate for your transfer fluid (water?) should be. As long as the exchanger meets the minimum requirements of your system, you’ll be OK.