We advise that if you are away from the property for less than 2-3 weeks, then leave all power switches on. If, however, you are going away for longer than 3 weeks, you can make a small saving by turning your OFF PEAK SUPPLY OFF, but leaving the MAIN POWER SUPPLY ON. This will stop the unit heating up on the off-peak periods, but the pump is exercised on a regular basis – reducing any potential problems on your return.
Inside your appliance a store of water is held within a copper cylinder, which will cool if the appliance is switched off. If the water held in the copper cylinder is allowed to remain cool for a prolonged period of time, the natural rate of corrosion of the copper cylinder will accelerate and the lifetime of your appliance can be significantly reduced. If all the power is turned off, the pump is not exercised on a regular basis and has an increased likelihood of seizing up.
We would not therefore recommend leaving your unit switched off for several months without the appliance being drained. Gledhill Response would be pleased to drain your unit for you at a subsidised rate should this ever be necessary.