As Mark above. We have a 406 system running radiant cooling. Our particular concern for this house wasn't the actual cooling. It has a considerable amount of glass and sits on the top of a mountain here. So heat was the main concern and radiant is a great answer. BUT, if the homeowner's left all there blinds open for a week in summer, they would be hard pressed to get the heat out of that large house; thus, radiant cooling was a great fit. They also have an HRV on a timer for fresh air and hydronic fan coil mainly for the dehumidification. But, all our radiant houses have ducting for fresh air (code). Except maybe the odd old leaky house that tore out their wood boiler. The benefit for our region, is we can downsize that ducting to only serve cooling and/or fresh air loads. About 1/2 our heating loads.