A Copper Alliance Member
Design and Installation Data:
Copper Tube for Heating Systems
Copper tube is popular for heating systems in both new and remodeled buildings. Contractors have learned through experience that, all factors considered, copper tube remains superior to any substitute material. The advantages of light weight, choice of tempers, long-term reliability, and ease of joining, bending and handling are of major importance.
For example, where rigidity and appearance are factors, drawn tube is recommended. Annealed tube is particularly suitable for panel heating, snow melting, and short runs to radiators, convectors and the like. With annealed tube the need for fittings is reduced to a minimum, saving substantial installation labor and material.
Forced circulation hot water heating systems provide uniform heating and quick response to changes in heating load, require little maintenance and can be easily zoned to provide different temperature levels throughout the buildings. These systems use the smallest and most economical tube sizes with soldered joints and require little space for the installation. Also, in combination with the heating system and where permitted by code, domestic hot water can be heated directly—eliminating the need for a separate water heater.
Design and installation data for heating systems are given in The Heating and Air-Conditioning Guide, published by the American Society for Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE), as well as in literature published by manufacturers of boilers and other heating devices. Those publications should be consulted for detailed design.
Steam-Heating Return Lines
For steam-heating systems, especially return lines, the outstanding corrosion resistance and non-rusting characteristics of copper tube assure trouble-free service and maintenance of traps, valves and other devices. On condensate and hot water return lines, it is recommended that the last two feet before the heating medium should be double the size of the rest of the line. For example, if the return line is 1-inch tube, enlarge it to 2-inch.
Radiant Panel Heating
A modern application of an ancient principle, radiant panel heating, can be used successfully in nearly all types of structures. In panel systems, low-temperature hot water, circulating through coils or grids of copper tube embedded in a concrete floor or plaster ceiling, warms the surfaces and the air. Panel systems offer uniform heating and comfort, an invisible heat source, complete use of the floor area, cleanliness and the elimination of dust-carrying drafts.
Copper tube is the ideal piping material for floor and ceiling panels because of its excellent heat transfer characteristics, light weight, long lengths, corrosion resistance and ease of bending, joining and handling. Soft temper tube in coils is commonly used for sinuous (curved pattern) heating layouts, since it is easily bent and joints are reduced to a minimum. Hard temper tube is used for mains, risers, heaters and grid-type heating coils.
Location of the heating panel is relatively unimportant for the comfort of room occupants, but it does depend on the architectural and thermal characteristics of the room. Floor installations have the advantage of low initial cost and are particularly suitable for garages, schools and churches. They are generally designed to operate at a maximum surface temperature of 85°F. Above this temperature, occupants become uncomfortable.
Ceiling panels can be operated at higher surface temperatures and heat output levels than floor panels. Heating panels respond quickly to changes in heating load, have low thermal storage and require only a simple control system.
The tube sizes of heating coils chiefly affect the hydraulics of the heating system and are relatively unimportant from the standpoint of heat output of the panel. For sinuous floor coils 3/8-inch, 1/2-inch and 3/4-inch soft temper tube are generally used with a 9-inch or 12-inch center-to-center spacing. For ceiling panel installations the sinuous coils are formed of 3/8-inch soft temper tube with a tube spacing of 4 inches or 6 inches. Soldered joints are commonly used.
