I have customers who wants me to build a log home that will be used seasonally, for about two months of the summer and another two months in the winter. During the rest of the year they want to leave the house closed up and unheated. We're at the edge of the Rocky Mountain Front Range in eastern British Columbia, and winter temperatures often fall to 20F. I've discouraged the clients from installing a hydronic heating system because of the difficulty of draining it twice a year (draining the domestic water will be headache enough), but what other potential problems should I be thinking about? I'm concerned that the radical swings in temperature could damage interior finishes