For dumping purposes you could bury a coil of pexal pipe in the ground(ground temp cooler) down about a metre , use a 3way diversion valve through the solar controller
Solar Hydronic
(40 posts) (17 voices)-
dymonite69
MemberSolar hydronic is not cost-effective because the period you want heating is the time you have the least amount of sun.
You can determine the absorber requirements from first principles.
The recommended amount of solar glazing to keep a passive solar home is around 15% of the floor area of the house. Since a solar water heater is slightly less efficient at converting the sun's energy, you are looking at 20%.
So for a 200m2 house you would need 40m2 of absorber area. A 40 tube ET is only about 5m2 in area.
Ground source heat pumps are a more efficient means of utilising thermal energy if you want a radiant system. Ground temperatures are stable throughout the seasons and can be used continously for heating or cooling by reversing the cycle.
Posted Thursday 28 Jan 2010 @ 5:42:52 am from IP # -
ghostgum
MemberAnother way to do the calculation is to say that a 5 star 200m2 house will require about 150MJ per m2 for heating, or 30000MJ per year, or 300MJ per day if heating is required on 100 days only.
One square metre gets about 1kW of solar energy, and you get about 4 of these per day in winter. 1000 * 4 * 3600 = 14MJ per m2. So the collector area needs to be about 20m2. That assumes that the collector is perpendicular to the sun, and that it isn't a cloudy day. If you get a sequence of cold overcast days, then you will be falling back onto gas heating. The best you could hope for is to get about half the heating requirements. dymonite69's figure of 40m2 is probably about right if you want to deal with partly cloudy winter days, and you will need storage of at least 2000l. 2000 litres of water being heated from 40C to 70C requires about 250MJ.
But it's hard to add extra windows, and its hard to add thermal mass when on asuspended wooden floor.
Posted Thursday 28 Jan 2010 @ 9:21:17 am from IP # -
dymonite69
Member14 MJ/m2 in Winter is a bit generous for Adelaide. Probably around half of that, 7.7 MJ/m2. Using your calculation that brings the absorber area back to 36m2.
As you mention a true passive solar design may be difficult to retrofit. But I was merely indicating the system requirements to drive a purely solar hydronic heating arrangement.
Again if you are going to fork out the money for a radiant heating system then a ground source heat pump might be a cheaper and more flexible option.
Posted Thursday 28 Jan 2010 @ 12:11:12 pm from IP # -
JohnSamin
MemberThanks for continuing the post. In our case we have a 1950s double brick 3 bdrm x-guvvy, brick internal walls, timber floor. We've expanded the north facing double glazed glass to 18m2. So all up + hydronic about 25m of apature.. At 170m2 living area that's 14%. I don't want to cook the house during the day, but do want to load up the thermal mass I have. Of course I do expect to use some gas...
In my case I think loading the thermal mass I have is a more cost effective, in terms of building my hydronic system. Probably geothermal based heat pump would have been more cost effective, but building the solar hydronic is definately more fun
We live in inner Canberra, and are doing a full rennovation anyway, this is one part of that renno.
Posted Thursday 28 Jan 2010 @ 8:19:31 pm from IP # -
Anonymous
UnregisteredYou can take this Solar Hydronic heating system for your house. It is a nice energy saving technique. And price of that system is also reasonable.
Posted Wednesday 28 Apr 2010 @ 6:45:07 am from IP # -
Another option for compact heat exchangers for solar heating project:
http://www.brazetek.comPosted Saturday 29 May 2010 @ 7:04:20 pm from IP # -
Ueee
MemberWow, I know i am only a new member and this is an old thread, but finding this is great, i am also in canberra and looking into solar hydronic heating, we have been in our house only a few years and have been digging into heating options for a while- all the house had was elictric wall heaters-yuk. My wife likes reverse cycle, but i don't want to see all the electricity from our pv system chewed up by heating costs. it would be great if we could get in touch, if you would like to email me please do at ewangibson84@hotmail.com. Thanks!
Posted Saturday 26 Mar 2011 @ 5:24:01 am from IP # -
Buzzman
MemberThick socks and warm jacket much cheaper than solar hydronic, or any other kind of hydronic for that matter.
Why warm air when you can warm yourself easier and cheaper?
I call this the "Eskimo principle".
You don't see too many of them lugging around huge heating units. Lightweight reindeer skin and sealskin clothing much warmer - even if these days they use polar fleece rather more often....
Posted Monday 28 Mar 2011 @ 7:04:04 am from IP #
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