Hot Water Service Circulators
Hot water service circulator pumps are designed for domestic hot water and small heating systems as well as cooling and air-conditioning systems. These pumps will work for both open and closed systems but should be installed indoors. These pumps will move thin, clean and non-aggressive and non-explosive liquids, including softened water, which do not contain fibres or solid particles. If used in refrigerants, these cooling liquids should not contain any mineral oil.
The Grundfos Comfort series of hot water service circulator pumps work at optimum performance with liquids of a viscosity similar to pure water, namely one square millimetre per second, and at ambient temperatures of 20 degrees C. If these pumps are used with liquids of higher viscosities, their hydraulic performance will be reduced. For example, water with 50 per cent glycol content has a viscosity of 10 mm2 per second, or 10 times that of pure water. This will reduce the pump's performance by 15 per cent.
The pumps will work at a liquid temperature range of between +2 degrees C and +95 degrees C. However, Grundfos recommends that the temperature be kept as low as possible, such as 65 degrees C., so that lime deposit build-up is minimised. Grundfos also recommends that a minimum inlet pressure of 0.5 bar is required at the pump suction port to prevent cavitation noise and any damage to the pump bearing.
The Grundfos Comfort series service circulator pumps are available in two pump housings that incorporate isolation and non-return valves, or are prepared for such valves to be fitted. A stainless-steel spherical separator separates the stator from the water-conducting part of the pump. The motor may also be separated from the pump housing for ease of maintenance.