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Old 02-14-16, 03:29 PM   #585
jeff5may
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Like I stated before, the closed-loop approach you are taking, combined with the two heat exchangers you have, could be all you may need to heat and cool your greenhouse. From your preliminary results, you seem to be getting more solar gain than you can capture on sunny winter days. Using the shotgun exchanger to sequester more of the BTU's in your fish tank water may help in more ways than one. First, it will transfer all the heat you tell it to into the cool water. Second, it will delay your vents from opening, directly proportional to the BTU's routed to the fish tank. Higher flow rates (water and/or air) will yield a diminishing increase in heat transfer. As you posted, I also suspect the bottleneck in this heat scavenger will be the air to water HX surface area, and to a lesser extent, the airflow through that HX. Whatever dT the water picks up in the process will be gobbled up by your wort chiller coil. Running straight tank water through the shotgun HX would not get you hardly any more heat transfer, but it would highly increase the chances of fouling and corrosion.

The summer use of this closed-loop heat transfer mechanism should not be overlooked. The supply and return lines to the ridge HX could be teed into, and a chiller loop could be plumbed in. During sunny hours, the fan (and possibly water flow) for the ridge HX could be shut off, forcing all the chilled water through the wort coil. Strategically setting up a shady, calm spot below the chiller coil will become the hangout joint for your fish that are not comfortable in hotter water. Even though you might not measure much overall temperature drop, your water chemistry will thank you for it.

Last edited by jeff5may; 02-14-16 at 06:33 PM..
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