Danfoss VLT HVAC Design Manual page 22

2 Introduction to VLT HVAC Drive
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Illustration 2.7: Discharge dampers reduce power consumption somewhat. Inlet Guide Vans offer a 40% reduction but are expensive to
install. The Danfossfrequency converter solution reduces energy consumption with more than 50% and is easy to install.
2.7.5 Example with Varying Flow over 1 Year
The example below is calculated on the basis of pump characteristics ob-
tained from a pump datasheet.
The result obtained shows energy savings in excess of 50% at the given
flow distribution over a year. The pay back period depends on the price
per kWh and price of frequency converter. In this example it is less than
a year when compared with valves and constant speed.
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Energy savings
P =P
shaft shaft output
Flow distribution over 1 year
MG.11.B9.02 - VLT ® is a registered Danfoss trademark
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VLT HVAC Drive Design Guide