Trane TRG-TRC016-EN manual Primary-Secondary System Operation

period two

Chilled-Water System Design

notes

System Operation

s
u
p
fl	pl
		y
o
	w
production
loop
					e
					ip
				p
				s
			s
		a
	p
y
b

return tee

supply tee

distribution loop

	d
		e
f			m
				a
l					n
o						d
		w

Figure 59

Primary-Secondary System Operation

We have seen that the production and distribution loops of the primary- secondary system act independently. The next consideration is to match the capacity of the production loop to the load of the distribution loop. The operation of a primary-secondary system focuses on the direction and amount of flow in the bypass line.

At the supply tee, which connects the supply and bypass pipes, a supply-and- demand relationship exists. The total water flow from all operating production (chiller) pumps is the “supply” flow. The “demand” flow is the total water flow required to meet the loads on the cooling coils. Whenever the supply and demand flows are unequal, water will either flow into, or out of, the bypass pipe at the supply tee.

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