Sand battery heater

if wanting to dump excess electricity and geyser is already in the mix
i would get a spare geyser tank and use it as a feeder to existing geyser
this is what i did , got a tank for free only had to remove it

so whatever it is heated to it just reduces the work your normal one needs to do
thus timeshifting some after hours geyser consumption can also use a small element and have it running all day leaving capacity for kettle etc

i have a 1kw element on mine , switch it on early morning to drain the battery further if not empty enough to optimise savings
then switch it off once i see the hrs to charge full is gonna be too late to get battery full
once the battery is full late afternoon i switch it back on to use excess again
 
I plan to try this out next winter. While it might still require some gas to heat my bedroom, if I can raise the temperature a few degrees without additional cost, that's a positive outcome.
 
OP-
This technology has been in use in places like New Zealand since the 70s.
Putting a geyser heating element into sand I don't think will end well.
If I were you I'd rather use proper nichrome wire and embed that into a ceramic type of material like they do with panel heaters. I forget how they do it, but Google should help.
 
Why not just use an oil heater instead? It is portable, and has an adjustable thermostat, which cycles the power to the heating element on & off (which saves on electricity consumption) - unlike a conventional bar element heater, which has no such capability.

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Ivan Leon said:
Why not just use an oil heater instead? It is portable, and has an adjustable thermostat, which cycles the power to the heating element on & off (which saves on electricity consumption) - unlike a conventional bar element heater, which has no such capability.

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If I heat up the oil heater during the day, will it still be warm in the evening when I require it?
 
BBSA said:
If I heat up the oil heater during the day, will it still be warm in the evening when I require it?
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The usual way to utilise an electric oil heater is that you only turn it on when you need it to warm the room, otherwise you leave it switched off. Most electrical appliances that do not have internal batteries as well (like a portable radio, laptop, cell phone or tablet), need a constant supply of electricity to power them - so if you have solar power, then you will only need sufficient battery storage capacity to allow you to utilise any electrical devices that need power to operate during the night, like exterior lights, a fridge, and the oil heater.
 
Willie Trombone said:
Do you have double glazing and other insulation? Efficiency first IMO - works in winter and summer.
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Also, consider carpets & underfelt for the bedroom/s & living room, and linoleum for the dining room, kitchen & bathroom, instead of ceramic tiles (if your flooring has them).

You can also reduce / eliminate any airgaps in windows & doors by using those self-adhesive foam sealing strips you can get at hardware stores.
 
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Ivan Leon said:
The usual way to utilise an electric oil heater is that you only turn it on when you need it to warm the room, otherwise you leave it switched off. Most electrical appliances that do not have internal batteries as well (like a portable radio, laptop, cell phone or tablet), need a constant supply of electricity to power them - so if you have solar power, then you will only need sufficient battery storage capacity to allow you to utilise any electrical devices that need power to operate during the night, like exterior lights, a fridge, and the oil heater.
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He wants heat at night from solar.
 
Speedster said:
He wants heat at night from solar.
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Solar charges the batteries during the day - appliances (lights / fridge / heater) utilise stored electricity from batteries via an inverter at night - cycle repeats every 12 hours - for an effective solar installation, the batteries should always be capable of providing power for the entire night without being fully depleted... :)

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Ivan Leon said:
Solar charges the batteries during the day - appliances (lights / fridge / heater) utilise stored electricity from batteries via an inverter at night - cycle repeats every 12 hours - for an effective solar installation, the batteries should always be capable of providing power for the entire night without being fully depleted... :)

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Thank you for explaining that. I had no idea how conventional solar systems work before you enlightened me.
 
Gordon_R said:
Sounds like a really bad idea IMO. You need a whole degree in heat transfer and thermodynamics to make it work. Sand is cheap but not ideal, and you need fans and other equipment to get the heat out when you need it.
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Several metal rods welded between two metal plates with the heating element attached to the bottom and a heatsink attached to the top. And a fan. That should do it.

Large insulated water tank would be a better idea IMO. Pumped through a radiator in the house.

EDIT: Saw a youtube video a few years back where some guy in Alaska built his house on top of a giant insulated concrete reservoir of water that is heated by solar. He ran his "consumption" water through coils of copper pipe placed in that tank to heat it up and also ran his underfloor heating through there.

Might have been this one:

 
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Speedster said:
Thank you for explaining that. I had no idea how conventional solar systems work before you enlightened me.
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Apparently the Ozzie PM (supposedly a 'very highly educated' & respected individual) could have used this simple explanation, as he seemingly has NO cooking clue how solar power actually works...

 
tetrasect said:
Several metal rods welded between two metal plates with the heating element attached to the bottom and a heatsink attached to the top. And a fan. That should do it.

Large insulated water tank would be a better idea IMO. Pumped through a radiator in the house.
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Think they are saying water isn't as good as you think as it starts evaporating etc... You can't heat it as much as sand..... But would take a lot to overcome the 5x higher specific heat capacity of sand!?

-around 20kg/L of water you heat 40 degrees uses about a 1kwh. So maybe take it to almost 100 (I. E. Add 80) and that's 2kWh
- to do the same 2kWh with sand you'd have to heat by 400 degrees... Which sounds mental but is possible... And won't explode like a steam pressure vessel.

Hmm certainly interesting isn't it!
 
richjdavies said:
Think they are saying water isn't as good as you think as it starts evaporating etc... You can't heat it as much as sand..... But would take a lot to overcome the 5x higher specific heat capacity of sand!?

-around 20kg/L of water you heat 40 degrees uses about a 1kwh. So maybe take it to almost 100 (I. E. Add 80) and that's 2kWh
- to do the same 2kWh with sand you'd have to heat by 400 degrees... Which sounds mental but is possible... And won't explode like a steam pressure vessel.

Hmm certainly interesting isn't it!
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Yeah but it's a lot easier, more versatile and safer to work with lower temperatures because you can use water as a heat transfer fluid as well as for storage. You can also use cheap household PEX piping, fittings, and standard water pumps.

Good luck trying to extract and transport heat from 450 degree sand. Water is out of the picture so you'd have to have oil flowing through welded metal pipes cause even the solder would melt. And forget about pumps, you'd have to design it to circulate via convection.

A 1000L water reservoir could store about 70kwh going from 20 to 80 degrees. And that's only 1 cubic meter of water.
Dunno about you, but that's a lot of excess solar power in my book.
 
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tetrasect said:
Yeah but it's a lot easier, more versatile and safer to work with lower temperatures because you can use water as a heat transfer fluid as well as for storage. You can also use cheap household PEX piping, fittings, and standard water pumps.

Good luck trying to extract and transport heat from 450 degree sand. Water is out of the picture so you'd have to have oil flowing through welded metal pipes cause even the solder would melt. And forget about pumps, you'd have to design it to circulate via convection.

A 1000L water reservoir could store about 70kwh going from 20 to 80 degrees. And that's only 1 cubic meter of water.
Dunno about you, but that's a lot of excess solar power in my book.
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But putting a m3 water tank in your bedroom isn't really feasible. Sticking a bucket full of sand on top of a closet is a lot more doable.
 
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