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Variable Speed Pumps Theory and Application. What Is Variable Speed Pumping?. Pump changes speed based on load Curve shifts on both head and flow axis More speed – more flow and head Set point or outdoor reset Zone valve/TRV or fan coil systems Variable speed injection mixing.
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What Is Variable Speed Pumping? • Pump changes speed based on load • Curve shifts on both head and flow axis • More speed – more flow and head • Set point or outdoor reset • Zone valve/TRV or fan coil systems • Variable speed injection mixing
Universal Hydronics Equation • GPM = BTUH ¸DT x 500 • Change heat load, change GPM needed • Change DT, change GPM needed • BTUH = GPM x DT x 500 • Change GPM, changeBTUH output • Change DT, changeBTUH output
Variable Speed Pumps • Setpoint – 00-VS • Maintain specific water temp • Maintain specific Delta T • Outdoor reset – 00-VR • Injection mixing • Change supply water temp based on outdoor temp • 003 thru 0014
The Many Uses of the 00-VS • Fixed set point • Adj. set point 30°- 210°F • RFH, radiators • Fan coils • Optional boiler protection • Program with dip switches & range dial
Injection & Primary-Secondary • Perfect for multi-temp, multi-load systems • Key is tee spacing • 6” or 4 pipe diameters • At least 6” straight pipe on either side of tees • 1’ thermal traps
In The Delta T Mode • For zone valve systems • Set for 200DT • All zones calling –full speed • As valves close –slow down! • Maintains 200DT • Reduces noise,smoother operation
Same Thing Only Different… • Panel radiators, baseboardor zoned radiant • TRV’s or valve actuators • 00-VS speeds or slows based on heat calls
How Does It Work? • All zones calling – lowestflow resistance • As zones close, flowresistance increases • System curve “backs up” pump curve • Noisy traffic jam! • 00-VR is traffic cop!
Variable Speed– Outdoor Reset • Perfect for radiant jobs • “Delivery” reset • Changes SWT based on outside temps • Comfort and economy of operation • Lots of features… • Adjustable heating curve • Adjustable min/max SWT • Adjustable boiler protection • System pump relay
Changing Conditions Fixed SWT Variable SWT • Heat loss change every day • Fixed water temp =variable run times = cycling in mild times • Variable water temp =fixed run times =less short cycling =greater efficiency
How Does It Know? • Four key numbers • Outdoor Design Temp • Mix Design • WWSD • Mix Start • Reset ratio = Mix Design Temp - 720 720 – Design Outdoor Temp
= 72 - 0 = 72 Let’s Do One… • Mix Design = 130, Outdoor Design = 0 • 130 – 72 • 58 0.8
What Does 0.8 Mean? • Radiant water temp increases 0.8 of a degree for every 1 degree drop in outdoor temperature • To program: • Move dial on VR control to correct ratio
30,00060 x 500 Pipe & Pump Sizing • Radiant system – 30,000 BTUH, 100DT • 6 GPM, 5’ head loss • 1300 SWT, 1200 RWT • RFH supply pipe - 1” • Injection pipe sizing: • GPM = • GPM =1.00 • Injection legs = ½ • Taco 003-VR • Valve 30% open 1300 Radiant Supply 1800 Boiler Supply 1200 Radiant Return