sierra--check it out on the net,the new models are glass tubes that have a copper electrode to transfer heat to a manifold which water passes through and is recirculated via a vane pump back to the holding tank.
these systems are in use all over the world its another aussie invention with chinese industrial might to manufacture the tubes,they are not 28 years old its a relatively new method.
and with a backup booster heater burst pipes are a thing of the past in addition to the pressure relief valve on the stainless steel tank with a 20year warranty.
its a no brainer when factoring the replacement costs of traditional off peak or gas or as in my case an on demand system.
the cost differential on replacement of an on demand system with off peak as opposed to evacuated tube is at basic entry around $1k after rebates plus ongoing power savings that cannot be taxed as opposed to solar power
