The December 1997 Hydronics Workshop column showed several ways of using diverter tees in hydronic systems. This month we’ll crunch some numbers to get the head loss of a diverter tee piping arrangement, as well as find out how the flow splits up when it encounters such a piping configuration. We’ll also continue the discussion of gravity head in downfed risers. But first let me deliver the obligatory disclaimer.
The concept of “flow resistance” discussed way back in the February 1997 Hydronics Workshop column, is a good way to predict what happens in diverter tee piping systems. You’ll recall the basic idea of flow resistance is that each pipe, each fitting, valve, heat emitter or other component in a piping system can be given a resistance value based on how “restrictive” it is to flow. When all the piping components form a series circuit their flow resistances are added up to get the total resistance of the circuit. This in turn can be used to estimate the head loss of the piping circuit at any flow rate.