Arahant April 5, 2013 02:09 AM Interesting, but i dont see how the water is coming in so warm, if its getting pumped in through pipes that are in the ground, wouldnt they be alot cooler even in temperate regions. I mean that would be horrible to have such hot/warm water to shower with or drink when your already trying to escape the heat.I feel like im missing something, for one thing why would you even need to heat the water if its coming in so warm. It almost seems like this is a method for creating cold water rather then warm water(well it makes both), I dont know i honestly dont understand this, i know i must missing something. Mrk White April 5, 2013 04:19 AM Interesting idea, I do not doubt there can be an efficiency improvement for certain cases... but I think that overall energy consumption tests should be done before claiming a percentage of improvement. This is why: The cold water in the system will be colder. So when I have a shower and I mix hot and cold water, I will have to use a higher proportion of hot water for the same result, and this would require more energy than without the invention. Anyway, thumbs up to Hal Slater. Salut! Samuel Holden Bramah April 5, 2013 06:24 AM Mrk White I agree, but a way to circumvent that problem would be to take the "cold" water from the mains system to your shower mixer tap, so you would be using the "really cold" water in the tank for drinking or other cold uses but "street cold" water for showering and maybe the washing machine or dishwasher etc. Graham Aikman April 5, 2013 07:27 AM i'm jus' sayin' but this guy dint invent this, this kind of thing has been known about for years, of course it works its the laws of thermodynamics. you'd be better fitting a ground source heat pump in your garden, and then linking it with an air source and this water based system in order to produce maximum heat output. jus' sayin' Ian Madden April 5, 2013 08:50 AM He should have a model that integrates hot water recirculation. also how much cold water has to be brought into the house and used to keep up with usage of hot water i wonder RedBaron April 5, 2013 08:53 AM This is not a new idea at all. Geothermal system work like this. But water is pumped into pipes running underground a couple of meters where the ambient temperature is constant and warmish through out the year. It then gets pumped through a heat pump etc etc. Slowburn April 5, 2013 09:14 AM How does the efficiency compare to a passive solar water heater? If for what ever reason I wasn't using solar heat, I would heat the water with the waste heat from the refrigerator, air conditioning, or generator. Ed Campbell April 5, 2013 09:18 AM I love folks suggesting geothermal as an equal or better alternative. Got a spare $20-30,000? David Clarke April 5, 2013 10:21 AM Has anyone heard of thermodynamic panels? It is claimed that they can provide water up to 50°C from one panel about the size of a solar panel. They are basically a refrigerator in reverse. Bernd April 5, 2013 11:17 AM How is this better than an air to water heatpump? In order to extract a reasonnable amount of heat you would have to use lots of water. Not exactly eco-friendly.