replacing dhw cylinder

[bludger]

I have a copper cylinder, heated at night under economy seven, using one long immersion heater element. I intend to replace the cylinder with a more modern one with proper insulation

I there any real advantage to having a cylinder with two immersion heater elements entering from the side? My single element, which is 36 inches long, enters from very near the top of the cylinder.

When I have to give the hot water a boost the single element obviously heats up along its whole length. With two side mounted elements, the bottom one would be the economy seven heating and the top one the boost. Is this cheaper or more efficient or something?

 

[Goldberg]

The advantage is a second element is that it's (a) a backup and (b) convenient for heating a small quantity of water more quickly (and therefore more cheaply).

 

[bludger]

Of course! I should have seen that myself immediately.

Thanks for your reply.