Winter Solstice is Thursday December 21st @ 10:27pm EST in. North America this year. This corresponds to Friday, December 22, 2023 at 03:27 UTC.
I could automatically set mine up that way but right now it’s a manual recharge.
I’m with you. I can conceptualize it but building it?The heat capacity of water is x5 higher than dry sand, gram per gram. The sand is more dense, x1.8, lets call it x2. So you need 2.5x as much dry sand to equal the same heat capacity as water at the same temperatures. The benefit of the sand is you can heat it far hotter than water, ie without a phase change. If you fill a set volume with water, and heat it to 95C (100C being the boiling point near sealevel) you would need to heat the same volume of sand about 2.5 times as hot to be the same energy storage. Any heat recapture system will need to be able to operate at these temperatures.
I played with some figures based on water - since I have lots of that, and it would be easy to move this heat around.
For a 100-million btu heating season, and assuming the water temperture needs to be at least 40C to provide any meaningful heating, the delta t is about 55C-degrees.
100-million BTU's /55C-degrees/ 4btu/degreeC = 454 cubic meters of water storage (120,000USGallons) if I had zero losses... so I cut firewood instead.
That's why I set it up this way. I only use the bare minimum grid.
That makes sense actually.
we did it!
My TOU rate is. Whatever time I use it I pay the same amount. lol
Yea mine also. Flat rate no matter when it’s used..
well that makes things easier!
me either!, with the small exceptions:
The way my PLC is programmed right now, if I leave it alone, the inverter will just drop to standby and the house will un off grid power when the battery voltage drops below 50.5 That works out to about 45% SoC on my 14S Li NMC cells.
I've been reading in the forums over on Hearth.com. Interesting reading when it comes to buffer tanks. The move has been towards gasification boilers combined with buffer tanks. Some are building buffer tanks out of 500 gallon or larger LP tanks, using spray foam insulation on the tanks after modifying and cleaning the tanks.The heat capacity of water is x5 higher than dry sand, gram per gram. The sand is more dense, x1.8, lets call it x2. So you need 2.5x as much dry sand to equal the same heat capacity as water at the same temperatures. The benefit of the sand is you can heat it far hotter than water, ie without a phase change. If you fill a set volume with water, and heat it to 95C (100C being the boiling point near sealevel) you would need to heat the same volume of sand about 2.5 times as hot to be the same energy storage. Any heat recapture system will need to be able to operate at these temperatures.
I played with some figures based on water - since I have lots of that, and it would be easy to move this heat around.
For a 100-million btu heating season, and assuming the water temperture needs to be at least 40C to provide any meaningful heating, the delta t is about 55C-degrees.
100-million BTU's /55C-degrees/ 4btu/degreeC = 454 cubic meters of water storage (120,000USGallons) if I had zero losses... so I cut firewood instead.
Most of the buffer tanks out there will work well with solar as a dump load or using a water to air heat pump combined with a wood boiler. I like the flexibility of using the buffer tanks. I think it certainly would help with days of limited PV production and allows for using heat from different sources based upon the seasonal temps.
