Types of Hot Water Cylinders

What type of hot water cylinder contains two immersion heaters and no heat exchanger?

What type of hot water cylinder contains a heat exchanger coil and one immersion heater?

What type of hot water cylinder is fed directly from the cold water main?

What type of hot water cylinder is fed from a cold water storage cistern in the loft?

What item is this;

Should a TMV 2 or TMV 3 be used in NHS and healthcare facilities

What item is this;

Is the item in the picture centralised or localised;

If a customer has intermittent flow of water at a bath tap, what could this be caused by

Building regulation L states that all pipework within what distance of a hot water cylinder must be lagged (how many metres)