Q. Please inform me the size of lead pipes used for cold and for hot supply in an ordinary house with water on three stories. Also, what should be the size of the circulation-pipe as compared with the hot-water pipe?

A. The size is somewhat controlled by the ordinary street-pressure. A 1-inch main-supply from street-tap to rear of house, with 3/4-inch branch to boiler and as far as the baths, 5/8-inch beyond that, and 1/2-inch branches to basin-cocks and water-closet cisterns, will give a good flow at all times. If pressure is very strong and cost is an important consideration, these may be reduced one size. The return hot-water circulation-pipe should be at least 1/2-inch.