Worcester bosch highflow 400 combi boiler?

Hi, I have the Worcester bosch highflow 400 combi boiler I understand the principle of having the Heatbank but just was wondering am I wasting gas (money) because the heatbank is on constant and would purchasing a programmer be costs effective because it will allow me to put the heatbank on time so that it only comes on say twice a day?

Howard
November 2009