Hot water tank filling

[dan.b]

Hello,
I'm wondering if my hot water tank automatically refills in a particular way and what hardware I'd be looking for to distinguish the sequence involved.

I have a feeling that the tank only refills if the water goes down to a particular level; or if the taps aren't running and the boiler is turned on to heat the incoming water.

Essentially what I'm looking out for is a system that stops the incoming water from entering the tank if it's can't be heated or if it's being used (so as to stop a shower from prematurely running cold for example).

Any info much appreciated.

Dan

[Perry525]

For a hot water tank to fill you have one of two installations.
One a strong stainless steel tank that is connected to the mains water supply that is always full.
Two a copper tank that is weak and is only used at low pressure, filled by an overhead cold water tank, this will usually be full, but may at times run out of water if there are two many people using the water and the cold tank supply cannot keep up.
The first is very expensive, the second is a better system and is affordable.