Dual Immersion Heater Elements

[andyr]

I just got a 24" Copper Heating Dual element for my copper immersion tank its got one long element for "bath" and one Short element for "Sink" and an inbuilt 11" Adjustable thermostat (factory set to 60 degrees C) all this in one unit.

I heated up some water on "Sink" which then the inbuilt thermostat cut out - well thats working properly but I then wanted to get a full tank of hot water for a bath so I put the switch to "Bath" but because the bath and sink elements are both controlled by the one thermostat (in the neutral line) of course it would not put any electrical current to the bath element - so how do I overcome this? if the tank (even though only the top part) has reached temperature and cut out the thermostat how on earth do I heat up a full tank of hot water? - its got me beat.

Also the old element I took out of the tank the elements were curved upwards at the bottom like a u-shape and the new element is straight and I was wondering why?

Thanks.
Andy.