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PRESENTS
RICHARD A. WING
General Manager
ITI Certified TABB Technician
A Balancers Perspective on
PICCV Valves
Go with the Flow
Common Hydronic Formulas1 GPM = P X CV ( SEE NOTE )
2 BTU = CFM X 1.08 X T AIR
3 BTU = GPM X 500 T WATER
4 GPM = BTU
500 X T WATER
5 T WATER = BTU / GPM
500
6 T AIR = GPM X 500 T WATER OR BTU
CFM X 1.08 CFM X 1.08
7 GPM = FPS X (ID2 X 2.45)
8 FPS = GPM
ID2 X 2.45
(NOTE) CV = FLOW COEFFICIENT THAT WILL PASS A QUANTITY OF
60 DEGREE WATER THROUGH AN OPEN VALVE @ 1 PSI P
EXAMPLE:
CV 10 , P = 9 PSI
P X CV
9 X 10
3 X 10 = 30 GPM
Direct Return Piping
200% of terminal flow
100% of total flow
40% of terminal flow
THE FIRST ELEMENT SUPPLIED IS THE FIRST ELEMENT RETURNED.
Since the highest p is at the first element, the first element gets the lions share.
A time consuming balancing effort is required to test adjust and balance.
Reverse Return Piping3 Pipe System
100% of total flow
100% of circuit
100% of circuit
100% of circuit
THE FIRST ELEMENT SUPPLIED IS THE LAST ELEMENT RETURNED.
Since the p is equal at all the elements, the flow is also equal.
Little time is required to test adjust and balance
Flow vs. BTU Output
FLOW GPM BTU T EWT LWT
100% 30 300000 20 200 180
50% 15 270000 36 200 164
T = 20 F
Full FlowNo Balancing Valves / With Balancing Valves
50% Flowwith Balancing Valves / with PICCV
PICCV Pros/Cons
ADVANTAGES
1. FLOW STABILITY OVER A WIDE RANGE OF PRESSURES
2. LIMITS OVER PUMPING
3. OPENS AS P DROPS.
IT'S DYNAMIC
4. REDUCES INITIAL BALANCING TIME
5. ADD TO SYSTEM WITHOUT REBALANCING
6. ONE PIECE INSTALLATION RATHER THAN TWO PIECES: (ONE ATC VALVE AND ONE BALANCING VALVE)
DISADVANTAGES
1. NEED HIGHER TDH (MIN of 2.3')
2. NOT READILY ADJUSTED FOR FLOW INCREASE
(UNLESS CONTROLLER IS SET FOR 90%(ADJ) POSITION AT THE DESIGN GPM)
Perfect Application2 POSITION
PICCV
A PRIMARY LOOP CHILLED WATER SYSTEM WITH ONE "HEADER" TO SUPPLY MORE
THAN ONE COMPONENT. ALTHOUGH THE VFD (OR SEVERAL PUMPS IN PARALLEL)
WILL CHANGE THE TOTAL FLOW, THE INDIVIDUAL CHILLERS WILL VARY THEIR
CAPACITY AS SYSTEM P CHANGES.
VFD
RememberGo with the Flow.
Know where you are
Know the pressure