The Grundfos UP series 200 line of wet rotor circulators is unique to commercial building services. Most competitor pumps are dry runners. UP wet rotor circulators, on the other hand, are designed so that the water being pumped surrounds the rotor, cooling and lubricating the shaft and bearings. Wet rotor design eliminates the need for a fan to cool the motor. Fans are often a source of noise and vibrations that can resonate throughout a building via the pipe work. Eliminating the fan results in very quiet operation. UP series 200 pumps are available in cast iron construction for closed (heating and air conditioning) and bronze construction for open (domestic hot water) systems. Both cast iron and bronze UP series 200 pumps utilize laser welded stainless steel impellers to achieve high pump efficiency. The standard UP motors are suitable for variable speed drive applications.