I am looking for the most efficient way to heat our hot water once we put in a geo system and am having trouble understanding what would work best with whatever seasonal heat boost I will get from a desuperheater. I believe I will need a storage tank for the desuperheater's water, then a conventional water heater to raise the temp of the stored hot water to a useable level. So, two insulated tanks in a series with the second one set up to heat the water to a usable level. Both my plumber and two propane gas companies have told me I should get an on demand water heater. Yet, I think I have read that they are not the best way to go. One thread referred to a poll on this site a while back of professionals who were against them, however I was not able to find the thread with the poll and discussion, so couldn't read the reasons why. I think it may be because the stored water from the desuperheater might be a high enough temperatue at times that the on demand won't work as well/turn on. Is that it? None of the three men who suggested it have experience with geo systems. They just sell water heaters and like the instant, on demand types. I am taking out our buried oil tank, so unless I put an oil tank in my basement (which I don't want to do) I can't use our current water heater. Natural gas is not an option, it would cost $18,000 just to bring it to my house. So, it seems the options are electric or propane. But, which is better? Propane would run between $3.49 and $2.79 a gallon depending on my usage. Electric rates in my area run about 19.48 cents per Kwh, among the highest in the nation. Recently, I have been reading about heatpump waterheaters, and that they are more efficent than standard water heaters. Is that so? Do they work well? And, are they reliable? I would appreciate any advice about water heaters to use with a geo system. Thanks.