When is it supply, when is it return?

[ChrisConley]

My question is regarding hydronic heating and cooling systems.

Is there a standard that states when a pipe is considered 'supply' or when it is considered 'return'?

Does pressure determine tagging, or does temperature?

It's fairly easy in the space to determine supply and return, but in the mechanical room I end up flip flopping my tagging: Supply from what, return to what: the pumps or the boiler/chiller?

Just wondering what other people use as a design standard.

 

[RossABQ]

You can argue either way, but we standardized on temperature; if it's cold, it's supply, even if it is ahead of the pump.

 

[GMcD]

If it is leaving the source heater or cooler, it's "supply" to the terminal system. Fluid returning from the terminal system to the energy plant is "return" fluid. Period.

 

[simsd]

Chris if you are talking about what I'm thinking about, it's all about perspective. And yes, I too have seen the flip-flop. I usually break it down like this.

Entering the boiler - All piping leading to his would be return.

Leaving the boiler - All piping leaving is supply.

I hope this doesn't sound too elementary or stupid, but does the flip flop occur when you are looking at or thinking about the suction and discharge of the pumps?

 

[AbbyNormal]

Its a return, when all it supplies is the boiler



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