how do combi boilers work?

[bednobs]

hi, we have a combi boiler ans a water softener. As recommended we have a tap (cold tap in kitchen) that does not give softened water. This is the tap i use to fill the kettle for baby's bottles. The hot and cold come out of the same spout. However, whenever i turn the tap on, it runs warm/hot for a few seconds before going cold. Does this mean it's the softened water (from hot tap) or does it run past a hw reservoir or something?

[The Builder]

It shouldn't be anything to do with the boiler, Beds. I guess the cold supply to the tap is direct from the mains under the sink. Could you describe the tap........ single spout mixer? ...... two separate handwheels? ...... or a lever that you push left and right for H&C and pull up to open the tap?

[bednobs]

two seperate levers for h/c, single spout. I am just trying to establish i am not using softened water at all

[The Builder]

Because it's a mixer tap, there will inevitably be a little (softened) water in the body of the tap before the cold blows it out.
Combis contain a small (maybe around 10 litres) storage vessel to give you a start before the burner catches up. Depending on how good the tap is, if you push the cold lever (with the hot closed) then you should only get cold (unsoftened) water after the tap is purged.

If I understand your question properly, then you should get only soft hot water OR unsoft cold water depending on which is turned on.
Maybe I'm missing something?

[DaisyNonna]

Mine frequently does not.