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Combining 200 feet of pex with a Sand battery. Starting my first tests and progress so far.

100 foot of pex painted black thin plastic coating. mirrors.

100 foot of pex in sand battery

About 4 5-gal buckets of sand. covering pex pipe.

HUGE amount of styrofoam broken up, making like bean bags that I now have on top and bottom for insulation.

Recirculating pump pulling 50 watts.

For the last 2 days the heat in the battery has gone between 107 degrees to 132 degrees F

Before I put the sand battery on, I was heating a 5 gal bucket of water at 80 deg to 130 degrees in 5 hours.


The sand has been dried in my rocket oven, I destroyed 2 pumps before I learned that the heat was killing them, this recirculating pump made for heat works like a champ.

My main goal has been reached in being able to heat water for a shower with a 5 gal bucket, The secondary goal I have is to store enough heat in the sand to take a shower in the morning with the stored heat. I am almost to this point......
 

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Pretty cool!
Umm, I mean "hot" idea.

Are you just building heat in the sand or do you have an output plumbed in to use the heat?
 
I have taken about 3 showers from the hot water generated from this setup. I just take a 5 gal bucket of water out and 5 hours later I have hot water enough for a very good hot shower.

I did not know if this would work or not, so it just is a prototype. So for now I am carrying the water in. I figured out all I need to do is put 2.5 gal of water in the 5 gal bucket, then heat to about 180 degrees, bring that in add cold water till it feels right then have a shower, that makes for less weight to carry.

That said, I have 3 ideas of how this could be used.

1) add more sand to get perfect temp for growing plants.

2) remove some sand say go from 4 buckets to like 2 buckets, so the temp will rise higher and cook as a thermal cooker.

3) As is the temp is about perfect for making alcohol mash, or a methane as the bacteria would really like this temp range, so I might try my hand at making either.

4) If I switch to a metal pan inside and figure out how to protect my styro foam insulation, I may use hot air from my rocket stoves / solo stove DIY to heat via hot air. I would love to convert junk to hot showers.
 
Sand doesn't boil, but it also isn't quite as refreshing. So there's a trade off.
Yes there are trade offs.

Water that just sits can get bacteria to multiply in in which can cause problems if you are bathing in it or taking a shower in it.


As Mentioned, with sand you don't have to worry with steam, which can be explosive if not properly dealt with valves etc.


What I have been looking at is using the pex as a heat exchange so I can heat the sand with the water, then later use the same pipe to pull that heat back out of the sand.


Today I reached a temp of 140 degrees with the sand, I had put on more insulation on the pipes and that made a 10 deg difference. I have a few more tricks I want to try to squeeze out more from this system.


I have a large block of concrete that I want to test using it as a chimney, it has a large hole in the center already, I am thinking that I could put dry sand around the concrete to act as insulation. This makes me wonder what if I put a heating coil inside the concrete, then try to use that as a thermal battery.....


If nothing else, I have an emergency backup for a hot shower, and I am having fun trying different ideas.
 
Sand doesn't boil, but it also isn't quite as refreshing. So there's a trade off.
Sand has 20% the specific heat of water so you either have to get it really hotf, or use 5x the amount by weight to get the same performance as water.

So if your water if boiling maybe you're not using enough??
 
What a fun project! How many pounds of sand? I might try to play around with the math about how many BTU's you've got stored there.

I see you've got a bunch of the military grade solar panels that got dumped to the market. I was asked by a non-profit in Puerto Rico to check them out. They were offered to them but the panels had something big time wrong with them. I tested several and could never get more than 10 or 15 watts out of 200+ panel. (from a shaky memory since this was at least 5 years ago).
 

I found this video today....... Using the solar heat direct into water to heat the water for his fish....

So.... That would be another experiment I could run is to fill the tub with instead of sand, put in water and compare temps to sand...

But much of this has already been done as I thin k about it as there is specific heat for each substance...... But still :)
 
What a fun project! How many pounds of sand? I might try to play around with the math about how many BTU's you've got stored there.

I see you've got a bunch of the military grade solar panels that got dumped to the market. I was asked by a non-profit in Puerto Rico to check them out. They were offered to them but the panels had something big time wrong with them. I tested several and could never get more than 10 or 15 watts out of 200+ panel. (from a shaky memory since this was at least 5 years ago).



I have done the math using an un insulated 5 gal bucket...

There are 200 feet of pex line, 100 feet of pex line holds .9 gal so I have 1.8 gal of water in the pex line that is also heated.....

So revised figures.

250 watt hours in, ( to power the pump ) 810 watt hours out, with much loss because no insulation.....

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What a fun project! How many pounds of sand? I might try to play around with the math about how many BTU's you've got stored there.

I see you've got a bunch of the military grade solar panels that got dumped to the market. I was asked by a non-profit in Puerto Rico to check them out. They were offered to them but the panels had something big time wrong with them. I tested several and could never get more than 10 or 15 watts out of 200+ panel. (from a shaky memory since this was at least 5 years ago).

I got my panels for Santan solar, I am very happy with them they are running my mini split cooling my home now ;-)
 
Sand has 20% the specific heat of water so you either have to get it really hotf, or use 5x the amount by weight to get the same performance as water.

So if your water if boiling maybe you're not using enough??

This is not my first experiment. I first started with using a 240 V stove heating element in the sand with over 1,000 watts of power going to it. Sand got up to over 1,000 F when i put a leaf in it, it instantly caught fire. That was very fun, and I burnt the coil up doing that, but I have an idea of how to fix that for long term use.

This experiment is targeting a system that I just use solar heated water to see what it can do, and test various elements of this, I just wanted to get an ballpark of what this system can do....... Now lets say I was to add a solar panel with a coil in the sand, I could push that sand temp to over 180 degrees very easy with not much effort, then I could cook with this system, or have a very very long shower with the amount of shower temp water I could make with this setup.

I also have in mind using my coil with my rocket stove to run in line with this setup...... so that 130 degree water could be also brought up to a more handy temp...... I need to switch to a metal container instead of the plastic one I have now before I venture in that direction.
 
If you get to expanding it, a Fafco Solar Bear pool heater provides a lot of square footage with very low resistance.

Thanks for that tip..

 
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This is not my first experiment. I first started with using a 240 V stove heating element in the sand with over 1,000 watts of power going to it. Sand got up to over 1,000 F when i put a leaf in it, it instantly caught fire. That was very fun, and I burnt the coil up doing that, but I have an idea of how to fix that for long term use.

This experiment is targeting a system that I just use solar heated water to see what it can do, and test various elements of this, I just wanted to get an ballpark of what this system can do....... Now lets say I was to add a solar panel with a coil in the sand, I could push that sand temp to over 180 degrees very easy with not much effort, then I could cook with this system, or have a very very long shower with the amount of shower temp water I could make with this setup.

I also have in mind using my coil with my rocket stove to run in line with this setup...... so that 130 degree water could be also brought up to a more handy temp...... I need to switch to a metal container instead of the plastic one I have now before I venture in that direction.
why not just use a greater amount of water? cheaper, easier to dispose off and i dare say safer.
 
How is sand better than water?
Sand doesn't boil, but it also isn't quite as refreshing. So there's a trade off.
Yes there are trade offs. Water that just sits can get bacteria to multiply in in which can cause problems if you are bathing in it or taking a shower in it.

... whereas sand doesn't grow bacteria? ... so it's OK to bath or take a shower in it ?? :LOL:??
 
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... whereas sand doesn't grow bacteria? ... so it's OK to bath or take a shower in it ?? ??
can you take a shower with sand???

and how much bacteria do you have growing in your water heater right now?
 
What a fun project! How many pounds of sand? I might try to play around with the math about how many BTU's you've got stored there.

I see you've got a bunch of the military grade solar panels that got dumped to the market. I was asked by a non-profit in Puerto Rico to check them out. They were offered to them but the panels had something big time wrong with them. I tested several and could never get more than 10 or 15 watts out of 200+ panel. (from a shaky memory since this was at least 5 years ago).
Yeah one has to match the ohms to the solar panel. I am going to test a voltage booster as I am hearing they help get the most out for a heater coil.
 
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why not just use a greater amount of water? cheaper, easier to dispose off and i dare say safer.
So what is your suggested container for all of this water? How are you going to insulate all of this water? I am interested at what you your thinking, and what the cost would be for this proposal.
 
So what is your suggested container for all of this water? How are you going to insulate all of this water? I am interested at what you your thinking, and what the cost would be for this proposal.
many people build boxes out of wood lined with some water proof material- very inexpensive.
check out this site
 
many people build boxes out of wood lined with some water proof material- very inexpensive.
check out this site

I love that site have been there several times. So I guess you have not done this before? I have seen david poz on youtube who built a system like you mentioned on youtube, I have followed his experiments for some time.


Epdm rubber $175...

 
I love that site have been there several times. So I guess you have not done this before? I have seen david poz on youtube who built a system like you mentioned on youtube, I have followed his experiments for some time.


Epdm rubber $175...

I don't live in a freezing climate so no hat exchange system for me.

I'll be doing something more like this but maybe with a flat plate collector and maybe thermosiphon
 

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