Domestic cold water covers the water that is used in a home for showering, cooking, etc. This water comes either from a water supply system delivering water to many households, or from a private well.
Colebrook-White's formula can be used to determine the friction coefficient (l) of a turbulent flow. The formula is normally used to create diagrams where the friction coefficient can be read.
A condensing boiler is provided with a condenser, by which the water vapour produced by the burning of gas or oil in the boiler, condenses back into liquid water - hence the name condensing boiler. The energy contained in the vapour, would without a condenser, normally discharged to the atmosphere through the flue.
Conductivity transmitters measure the electrical conductivity in a liquid. This is done in order to avoid excessive salinity, which can cause corrosion in e.g. air-conditioning systems.