HYDRONIC PIPING SYSTEMS

MD NAIYER KALAM KHANSERIAL NO.- 18CLASS:- MECHANICAL (A4MB-37)FACULTY NO.- 12 MEB 368EN. NO.- GG9523

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CONTENTSHydronic Piping SystemsPiping ArrangementsSeries LoopDisadvantage of Series LoopOne-Pipe MainPath of One-Pipe MainTwo-Pipe Direct ReturnTwo-Pipe Reverse Return

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Hydronic Piping Systems

Piping Arrangements

The piping that is used to circulate hot or chilled water for air conditioning is called a hydronic piping systems.

Piping arrangements are the connection between the piping and terminal units.

There are four basic ways:1. Series loop2. One-pipe main3. Two-pipe direct return4. Two-pipe reverse return

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SERIES LOOPAll units are in series to form a loop.Water flows through each terminal unit and returns to generator and

pump.It is simple and inexpensive.It is limited to small, low budget applications.

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Disadvantage of Series loopMaintenance or repair of any terminal unit requires shutdown of

entire system.Separate capacity control of each unit is not possible.The number of units are limited.Inadequate heating in later units.

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ONE-PIPE MAINThere is one main pipe through which water flows.Each terminal is connected by a supply and return branch pipe to the

main pipe.Each unit is separately controlled and serviced.Later units may be too cool to heat the rooms adequately.

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Path of One-pipe mainThe path has least resistance.Water circulating in the main tends to flow through straight run, thus

starving the terminal unit.Special diverting tees are used at each supply branch.If the terminal unit is below the main line, a special tee is also

needed at return branch to prevent backflow.

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TWO-PIPE DIRECT RETURNWater temperature supplied to each terminal unit to be equal.There are two mains, one for supply and one for return.Two-pipe system allows each terminal unit to be separately

controlled and serviced.It is called as direct return because it bring back water to the source

by shortest path.Water takes from the pump to the first unit and back is shorter than

that from the pump to the units further away.

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TWO-PIPE DIRECT RETURNToo much water is going to the units nearest the pump and too little

to units furthest from the pump.Balancing valves can be installed in each branch but balancing

problem is difficult and requires considerable expenses.

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TWO-PIPE REVERSE RETURNThe balancing problem is resolved.The path length for the water is about the same for each unit.It is relatively simple process to balance the flow rates.Expenses nearly same for both direct and reverse return but in some

cases reverse return piping may be more costly.

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COMBINATION ARRANGEMENTSIt is combination of some of four basic ways.It takes the best features of each.It is chosen for high rise building where separate control is not

needed.Mainly reverse return system is coupled with other systems.It is simple and has low cost as compared to complete reverse return.

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