Santon unvented water heater

[Lange]

I have recently moved into a new flat which is fitted with the above. There are no instuctions on how to use it! We have one switch labelled 'Hot Water' and another set of switches labelled 'Booster'. If we use the booster for 1 hour this generates enough hot water for just over 1 shower. The 'hot water' switch does not seem to do anything when it is on without the booster.

I am concerned the 'Hot water' switch is not working, is it usual to only use a booster switch?

 

[gas4you]

Hot water switch will be for the bottom immersion heater that only comes on during the cheap rate period usually overnight. Round my way it is called economy 7 but different suppliers have different names. Leave this on 24/7 and you should wake up to a full cyliner of hot water.

Boost is just what it says, a quick boost for during the day when the electric is at expensive rate.