Protecting Against Leaky Heat Exchanger To the Editor: "Using Water Heaters for Radiant Heat" (11/98) was a great article, but I have one question about heat exchangers. If the heat exchanger were to develop any leaks, it seems possible for contaminated water from the hydronic coils to leak into the drinking water side of the system. Is that really possible or am I missing something? If such a leak did occur, it might be difficult to detect until someone got sick. A second question: With so much concern about earthquakes, how do the California building codes deal with preventing leaks in the pipes that run through the floors? David Blatt Corvallis, Ore. Bill Clinton responds: Although I have never known a flatplate heat