Variable Speed Pumps Theory and Application What Is

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

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, change BTUH output – Change DT, change BTUH 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

Multi-Temp, Multi-Load

Bypass – Boiler Protection

In The Delta T Mode • For zone valve systems • Set for 200 DT • All zones calling – full speed • As valves close – slow down! • Maintains 200 DT • Reduces noise, smoother operation

Same Thing Only Different… • Panel radiators, baseboard or zoned radiant • TRV’s or valve actuators • 00 -VS speeds or slows based on heat calls

How Does It Work? • All zones calling – lowest flow resistance • As zones close, flow resistance 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

Understanding Reset

Changing Conditions • 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 Fixed SWT Variable SWT Heat Loss Variable SWT Fixed Variable Run Time Variable Fixed

How Does It Know? • Four key numbers – – Outdoor Design Temp Mix Design WWSD Mix Start • Reset ratio = Mix Design Temp - 720 – Design Outdoor Temp

Let’s Do One… • Mix Design = 130, Outdoor Design = 0 • 130 – 72 = 72 - 0 • 58 = 0. 8 72

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

00 -VR Piping Arrangement

Pipe & Pump Sizing • Radiant system – 30, 000 BTUH, 100 DT – 6 GPM, 5’ head loss – 1300 SWT, 1200 RWT 1300 Radiant Supply 1800 Boiler Supply • RFH supply pipe - 1” • Injection pipe sizing: – GPM = 30, 000 60 x 500 – GPM =1. 00 – Injection legs = ½ – Taco 003 -VR – Valve 30% open 1200 Radiant Return

Wiring This Bad Boy…