Water tank as heat battery

Look up geothermal heating. Basically the same thing. It's good for maintaining a stable temp year round, but won't function as climate control unless you add a heater or chiller.

dont' know much about the efficiency though

>>1157255
yes works and as far as i know is done in some houses

>>1157255
Some people do this and run black pipes out into the sun, usually covered in some box. In places where it freezes there is either a heat exchanger with anti-freeze in the outdoor loop or the entire system uses anti-freeze. Some greenhouses use them too; everything from geothermal to Trombe wall.

The main design decision is if you live on flat ground or have access to a hill below your house, if you want to use solar. If your house is on a hill you can use passive solar (thermosiphon) to pump the water from the solar heaters into the water tank and into your house. No electric pump is needed with such a system, you just need to use large diameter pipe and as few elbows as possible. If you don't have a hill to use, you'll need to use an electric water pump.

>>1157255

It's been done, see the "Small buildings with internal STES water tanks" section :

https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storage

But these are almost certainly homes with extremely good insulation. Ye average drafty old wood home would lose the energy an order of magnitude faster.

You can actually make the calculations. Just take a heat transfer manual and work with it. It shouldn't be that hard.

But IMO the winter is too long for that.
Burning wood or something seems like Much simpler process.

Or you can have that water reservoir, calculate theheat loss per day at a stable temperature and get yourself a photovoltaic panel to replentish the heat loss. That's what i'd do.

>>1157396
That would be even cheaper then you'd think because you could use direct DC from the panels to a heating element.

>>1157255
This guy has done it and needs very little insulation. Heat loss can be used to keep humidity down in your basement.

Pipe this through google translate unless you master the language:
http://www.sondred.info/solvarme.htm

>>1159257
This was a good read, and I didn't need a translator!
The thing that guy built was for continuous use, not for long term storage.
Anyway, 20 cubic meters isn't that much so it won't keep warm that long...
People who heat with wood have usually 1-5 cubic meters of water for heat storage and you still need to heat often enough to realise that 20000 litres won't get you far.

>>1159347
20 m3 hot water represents an awful lot of energy.

20 m^3 * 1000 litres per m^3 * 80 degrees delta T * 4200 J/(K * kg) = 6720 MJ.

Wrap it in bubble plastic and it will last you a long time. And from my reading his situation was that he easily had excess energy and you really want to avoid boiling the water.

>>1159480
And how hot does the water need to be again to efficiently heat radiators? Input temperature of 40-50°C... Depending on the climate. You just got only half of the joules left. So at current electricity prices it a hundred a year. OP, don't spend too much on building the rig and the mechanism to actually heat it to 80°C. Don't even think about something as silly as bubble plastic, for starters the earth and the tank will crush it. Some XPS closed cell insulation maybe. And by the way, that shit is expensive. As are construction equipment (unless you have an excavator, like I do. Yay for me!) and the tank itself.

The Norwegian guy had a sane way of doing it. His tank looked like a IBC container and heat was used immediately. No long term losses as with a 20 cubic meter tank that just looses the heat to the ground eventually.

no matter how you insulate it, it will lose heat due to conduction and radiation

how much heat? get a heat transfer book

>>1157255
Will 20 cubic meters hold enough heat to actually heat your house throughout the winter?
And how would you heat that water, you'd need something that would "suck out" the heat of your house and pump it into the tank, because if you had just a pipe running though the tank the water would quickly reach equilibrium and store energy that wouldn't be enough to heat your home in winter for an hour

>>1157260
Geothermal is incredibly efficient. It beats the best gas furnaces by 10+% and is more than twice as efficient as standard air conditioning.