A night setback system is used to control a heating system. A night setback system will lower the room temperature at night, which reduces heating costs. Office type buildings are not used at night, so lowering the room temperature will not cause discomfort.
Natural refrigerants have no, or an insignificant, effect on the ozone layer and greenhouse effect. They are widely used in smaller applications, such as heating pumps, small chillers, and commercial systems.
The round shape of nodular graphite reduces the stress concentration and consequently, the material is much more ductile than grey iron. Nodular iron is normally used for pump parts with high strength requirements
A non-return valve allows a medium to flow in only one direction. A non-return valve is fitted to ensure that a medium flows through a pipe in the right direction, where pressure conditions may otherwise cause reversed flow.
NPSH (Net Positive Suction Head)
The difference between inlet pressure and the lowest pressure level inside the pump is called NPSH: Net Positive Suction Head. NPSH is therefore an expression of the pressure loss that takes place inside the first part of the pump housing.