Equivalent Thinking: Modern hydronic systems should be as 'hydraulically efficient' as they are thermally efficient

摘要

The design process for every hydronic system involves making estimates for flow rates and head loss. Some, designers use rules of thumb such as "figure 4 ft. of head loss per 100 ft. of pipe." Others look up piping head loss in tables or graphs. Still others use software to account for tube type, size, fluid type, fluid temperature, fittings and valves. Most methods for estimating head loss treat fittings and valves as "equivalent lengths" of tubing having the same size as the fitting or valve. Table 1 gives equivalent lengths of some common fittings and valves.