http://butlersunsolutions.com/html/pr_solar_heat_exchagne_wand-46-reg.html

in fact for a very simple heat exchager that works great.

use glycol. because copper pipe conducts heat far better.

@Hackius

Usually these systems augment, but not replace. You can put the hot water through a mixing valve and an on demand system. If the water is already hot enough the on demand does nothing, if it’s not warm enough the on demand system will kick on and bring up the temp.

The mixing valve is also important as half of the problem with solar collectors is during the warm months the water can be far too hot for domestic use.

Why not just make it a drain-back system? You don’t have to worry about freezing in that case, and it’s more efficient then adding glycol to the system. It’s also fairly easy to implement. An expansion tank might not be the worst idea either if you’re pressurizing.

I live in Minnesota. We routinely get below zero farenheit temps out here. Drain-back systems are of limited use when water will freeze in ten seconds(ever thrown a cup of coffee out and have it freeze before hitting the ground…I have). A separate heating loop with antifreeze is a much better choice. With a fairly simple circuit, you can also control how hot it gets in the summer. Just shut the flow off for a bit when it gets to hot. You need to ensure that the hot side can take the pressure or is vented.

I have been kicking around building a system for my new house here. I have great southern exposure for a 24′ x 8′ set of panels. I have also thought about constructing a “heat battery” to hold the heat from the summer months for home heating use.

or this statement
“Most evacuated tube systems require mains electricity for pumps, valves, controllers etc thus negating any gains over flat plate collectors. These complicated systems will almost certainly come with an annual service contract that will be linked to any warranty”
The reason why his system can use a battery power pump is because it doesn’t produce that much heat compared to evacuated tube.

He is simply saying that removing the need for a heat exchanger you get higher efficiency then an evacuated tube + heat exchanger. I’d like to see some independent analysis of this. I can guarantee though that places like Minnesota this will not be more efficient then a evacuated tube + heat exchanger system. You also have the problem of mineral build-up in the system when using potable water.

If an energy generator is more efficient it must therefore give out more energy for the same amount of energy input otherwise it wouldn’t be more efficient. in this case the input is solar radiation and the output is hot water.

“Not to scale” lol…

by the way, many solar systems can be run passivly at a cost of less heat output. if the consideration is energy in vers energy out just run a passive system. the only difference is the way you run the plumbing and pressure release valves.

if this system is used for central heating and air then a closed system could be used, a bladder or storage medium for heat could be burried in the back yard with a pressure release valve eliminating the need for any pressure or temperature sensing circuits. a 12v 20 watt solar panel could be tied directly for a charging medium to a sealed lead acid battery or a charge circuit could be utilized. the battery can power the air circulation fan and the water pump, if any power supply changes need to be made to accomodate the fan or pump a small step up step down circuit or possibly just a transformer would be needed. the controlling factor is the thermostat which is presumed to already be on mains power and for switching needs can operate a very simple on off circuit to control direct power of the pump and fan. if this is used for more than just heating or cooling a switching box can be tied in.

the requirements for a AC system of this nature is extreamly simple and energy conservative. it would hands down be more effecient than utilizing a heat pump currently claiming 300% effeciencies on websites. this system becomes more energy conservative if radient floor heating is utilized. for additional heating the system can pass through a tankless heater. solar heating of water does not have to be much to provide a profound savings, simply preheating water to 90f can heat a home and save a considerable amount of cash.

if one looks at radiant floor heating you will see only a small temperature differential is required to keep a home toasty and solar has frequently been employed with this system to do just that.

the only question one should be asking is, why dont more people take advantage of this? the answer is money, employing this system would eliminate the need for the AC industry because mantenence is significantly reduced with less electronic and mechanical systems involved and energy consumption is considerably lower.

like the credit card industry where its better to keep you in debt, the energy and consumer industry finds it better to keep you buying. its just good buisness.

well the beauty of a system like this especially if its coupled with radiant heating is that you can use a single 2.5 tankless heater as the supplimental heat, this unit is a meager $150 if i remember correctly. i have a whole house unit for $300. i think if one actually sat down and planned this out we would find its less than $5k total cost with radiant heat and perhaps $3k-$4k for regular central heat air radiator.

there are 3 costs that will be high, digging the holes, purchasing solar heater panels, having the bladder purchased and installed. these 3 items will most likely be handled by a contractor above all other items due to the customers inability or lack of desire to do the work themselfs.

http://www.freeimagehosting.net/uploads/2c8c64604b.jpg

Hackaday, my ass! This is ridiculous. Shit like that is commercially available outside of the US for MANY years. Like 25, or more. I have one on my roof for over 10 years.

Tankless water heaters are acualy more economical for alot of home owners. they only heat water when water is called for and for familys that have lots of kids they never run out of hot water.