Confusion over booster switch

We've had the Pulsacoil 2000 for 5 years since we moved into my flat. Until recently everything had been running fine (we had been told by the previous owners which switch they believed to be the booster switch for the tank) The system stopped working recently and we have ahd someone out to look at it who has now confused us as to which is the booster switch on the wall and which is connected to the economy 7. The switch we have now been told to leave on produces hot water, but after every shower it makes a noise as if reheating during the day. Should this be happening? How can we tell which is the booster switch if they are not labelled and all wires from the switches to the tank are behind a wall??
Thank you

Well the easiest way will be thus.
Run some hot water off. Day time.
Then switch both on.
When you hear the heater heating up.
Switch one off see if it stops, if not then try the other.
Which ever one stops the heater in the day. Will be the Boost or top heater.
Mike
MGC/H2O
Norfolk

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