On Thu, 19 Feb 2004 13:34:24 GMT, "William W. Plummer" wrote (with possible editing):
That is VERY significant. At my place, we have both radiant and baseboard. The radiant all has mixing valves to mix some of the return with the supply. I can't remember the exact details, but as I recall, radiant under concrete topped with tile is set somewhere around 110 deg F while radiant under carpet is set around 120 deg F. This compares with the boiler output which is fed to hot water and baseboard and is set around 180 deg F.
I'm not an expert, but I'd guess that's your problem.