Storing heat in bricks

AntronX said:

Water 1.163Wh/Kg/K * 65°C(dt) = 76Wh/Kg
Brick 0.278Wh/Kg/K * 550°C(dt)= 153Wh/Kg

Click to expand...

Run the figures for the same delta. That is a pretty ridiculous comparison.

As Oz stated, you won't be pumping bricks.

One thing you miss is one law of thermodynamics. Heat moves to cold, the higher the delta between the heat and cold, the faster the transfer. As delta lowers, the transfer will decrease. An object at 550C delta will emit heat at a rate very high. You will need some serious insulation to hold the specific heat of the object.

Zwy said:

Run the figures for the same delta.

Click to expand...

The point of bricks is 10x delta they can handle. And they stay solid unlike water. Heat exchanger is used to retrieve heat or clever design as with UK storage space heaters.

JJJJ said:

I spent hours reading about how one could trap heat in the form of water in underground cisterns. The presenter provided some fancy math.

Click to expand...

Underground is not good unless you can keep any water from touching the surface of the tank. Any water touching and it will transfer heat at a high rate even with good insulation around the tank.

JJJJ said:

Water is a good transport method for heat exchange. He was talking about free energy.

Click to expand...

No such thing as free energy, anyone who speaks of it is a quack.

JJJJ said:

I even tried an experiment based on his writings. At the end of the day he was smoke and mirrors. It’s not that water can’t be used to move heat it’s just that there is no free lunch.

Click to expand...

I'm building a garage/shop for the tanks and boiler. Any heat lost from the boiler and tanks will heat that building. The shop portion is for all the woodworking equipment that clutter my current shop and have spread across 3 buildings. Plus other things. We could use a garage and heated is a bonus.

JJJJ said:

Those are some impressive water tanks. Radiant heat has a proven track record. Look forward to future updates.

Click to expand...

This will be a multi year project. I started collecting pieces so I could plan the building. I needed to determine ceiling and door height as an example.

AntronX said:

The point of bricks is 10x delta they can handle.

Click to expand...

I understand that however you miss several key points I mentioned concerning thermodynamics. I work in mobile HVAC all thru the summer, I know just a little bit about moving heat energy. The fact is per gram, water is the better store of energy.

AntronX said:

And they stay solid unlike water. Heat exchanger is used to retrieve heat or clever design as with UK storage space heaters.

Click to expand...

The same thermal energy (btu's or Kwh) is required to charge a 10X delta substance as any substance of lower delta concerning available thermal energy for use. One can only extract the same amount of thermal energy as put in. The losses at 10X delta will be considerably higher however.

Those of you who think they can charge thermal storage to use all thru winter without spending a huge amount of money are living a fantasy. To get to that point, you will need a phase change medium. Technicalities aside, it isn't impossible but it sure isn't economical.

Quattrohead said:

Yeah in the UK we call those storage heaters and they run on the Economy 7 tariff, well at least they did when I was a kid 40 years ago LOL.
They had a manual damper on the top that you could adjust to regulate the heat output but they invariably were extremely hot in the morning and had no heat left by the end of the day so overall slightly useless.

Click to expand...

Things have moved on a lot since then. We have storage heaters Dimplex Quantums (the latest can be controlled via the internet) as we don't have access to a gas supply (as in natural gas not petrol). We store the heat in the bricks inside the heaters using overnight cheap rate electricity, which also charges our storage battery, and release the heat at set times throughout the day, where a fan operates, pushing air through the heaters, around the hot bricks and out as heated air. They are pretty efficient. We never run out of heat as used to happen with the older style. The older style had very little insulation and very little control, the Quantums are the exact opposite!
If anyone is thinking of designing and building their own 'brick heat storage' then looking the Quantums might give them some useful information.
I am not advocating that this process of storing and then releasing heat is the best process, though if you could use free energy during hot days and store the heat for a cold night (on the same day) then it might be a viable option. But isn't that what a lot of us do anyway and would it be simpler just to store the free energy in a battery and use that to power a heater when it gets cold?

AntronX said:

Water 1.163Wh/Kg/K * 65°C(dt) = 76Wh/Kg
Brick 0.278Wh/Kg/K * 550°C(dt)= 153Wh/Kg

Click to expand...

As part of the learning process regarding thermal storage, I ran across John Siegenthaler's training videos. Start with this part of the video comparing various storage medium and the volume required. He does talk about concrete and sand for the same temperature change compared to water.


While you might think super heating a medium to a high temperature is easy, it isn't as easy as you think, it may not be efficient and it may not be inexpensive to implement.

Hi. Some interesting ideas in here. I like that people are poking at the edges. Some things are viable, and some are not, but it never hurts to do the thought experiment or even some testing. That's how we find new ideas.

Geothermal (ground source) was mentioned in a negative light above, but I will say my ground source heat pump is on year 13 and I don't regret it a bit. Closed loop, and north enough to need some serious heat, but it works well for me. The bit of storage in the ground temp, coupled with the delayed ground temp swing for the seasons makes it especially good in the first 1/2 of winter or summer. That and radiant floors for the coldest couple months works well for me.

There is also a lot of mention above of losses when changing mediums, etc. That is true in one way, but in another, as long as all your heat losses are contained in the same envelope you are trying to heat, you are not really out anything heat wise. However, losses can happen if your heating system goes out to another building, like a boiler.

I like seeing the plans put into action. Keep your thinking caps on.

SunDave said:

Hi. Some interesting ideas in here. I like that people are poking at the edges. Some things are viable, and some are not, but it never hurts to do the thought experiment or even some testing. That's how we find new ideas.

Click to expand...

I wholeheartedly agree... to a point.

However, along those lines I recently heard something that really hit me.

“In the beginner’s mind there are many possibilities, but in the expert’s there are few”​

― Shunryu Suzuki

At risk of being labeled the "expert" (I'm not) I can stay I've been around this stuff for a long time and I've yet to see a sand and/or seasonal heat storage project that really panned out. To be honest I think many were purposely designed to relieve investors of thier money or garner government grants knowing full well they wouldn't pan out.

Still if anyone is going to crack this sand and/or seasonal heat storage challenge it will be someone who hasn't already figured out that it can't be done.

SunDave said:

Geothermal (ground source) was mentioned in a negative light above, but I will say my ground source heat pump is on year 13 and I don't regret it a bit. Closed loop, and north enough to need some serious heat, but it works well for me. The bit of storage in the ground temp, coupled with the delayed ground temp swing for the seasons makes it especially good in the first 1/2 of winter or summer. That and radiant floors for the coldest couple months works well for me.

Click to expand...

I too am on year 13 with my closed loop geothermal. Love it, only problem was a fan motor failed a few months before the 10 year warranty was up so it only cost me an $85 for a service call. Most of the trouble with geothermal that I've seen comes from inexperienced installers and/or open loop (pump and dump) systems..

Pump and dump is the worst (never ending problems), only way I'd ever consider ground source would be closed loop. I own a backhoe and could install my own loops easily plus install my own unit but with the new air to water units, I'd certainly run the figures for both.

Zwy said:

Pump and dump is the worst (never ending problems), only way I'd ever consider ground source would be closed loop. I own a backhoe and could install my own loops easily plus install my own unit but with the new air to water units, I'd certainly run the figures for both.

Click to expand...

If stats are to be believed (50/50 shot there...) the air source are getting much closer to the ground source. Still not quite there for sub -20F environments but very good progress. Now that I have the ground loop I would definitely replace the water source heat pump, but if I was building new I would look into air. The dumb design of the ones I saw so far have the water going to the outdoor part of the unit. That seems off to me.

I went with a waterfurnace synergy 3D. Heats air, hydronic and potable water (desuperheat), all in the same unit. Luckily I have a friend that does excavation. We installed my slightly oversized ground loop at about 10ft deep.

OzSolar said:

I too am on year 13 with my closed loop geothermal. Love it, only problem was a fan motor failed a few months before the 10 year warranty was up so it only cost me an $85 for a service call. Most of the trouble with geothermal that I've seen comes from inexperienced installers and/or open loop (pump and dump) systems..

Click to expand...

Nice to hear it's working for you. I agree on the open loop, pump and dump too. You would need perfect water for that to work long term. It just isn't likely to work out.

ksmithaz1 said:

You bury it in a portable volcano... Don't you know anything?

Click to expand...

IIRC , from my jewelry manufacturing days , 90% platinum could tolerate that amount of heat… about 3200- 3300 F , So technically it could be used , but at about 1000 USD per Oz on the spot market Today , X how ever many thousands of lbs the 2 inch thick plates the container weighed + fabrication cost and the resulting security team to guard it 24/7.

……… well…. With no profit to the builder it would cost at least Several Hundred Million dollars,
depending on platinums price.

Then you would have to find a way to insulate the white hot platinum container. This is overall a very bad idea.

It would be well out of the price range for everyone I have ever known…

I think a heat pump or some space heaters sound more practical.

Just sayin……..
J.

SunDave said:

If stats are to be believed (50/50 shot there...) the air source are getting much closer to the ground source. Still not quite there for sub -20F environments but very good progress. Now that I have the ground loop I would definitely replace the water source heat pump, but if I was building new I would look into air. The dumb design of the ones I saw so far have the water going to the outdoor part of the unit. That seems off to me.

Click to expand...

Much of the gains with air to water heat pumps is the use of thermal storage. Run the unit during the day, which also is the same time the sun will be out, with temps higher than at night. I'm always looking for efficiency curves on air to air units and never seem to locate any so it is hard to know at what temp the efficiency drops off. Many use the heat strip anyway when temps get very cold.

The reason for the water/glycol to the condensing unit is everything can be packaged into the outdoor unit such as circulator pumps and easier install as a monoblock. Just run water lines and electric to the house.

Water to water is very efficient if used with radiant heat, air to water with radiant will not be as efficient but should be more efficient than using a heat exchanger in a plenum with water to water or air to water. Low temp emitters allow the thermal storage to supply heat for a much longer time with the increased delta of the tank between cycles. I believe this is the move forward with radiant heat and thin plate emitters. As with solar systems, covering the first 90 to 95% is easy, it is the last 5 to 10% that is costly. One option is of course additional heat generating capacity with gas condensing boilers or just use electric resistance when heat pump efficiency drops below 1:1.

SunDave said:

I went with a waterfurnace synergy 3D. Heats air, hydronic and potable water (desuperheat), all in the same unit. Luckily I have a friend that does excavation. We installed my slightly oversized ground loop at about 10ft deep.

Click to expand...

I can do the ground loop myself, I have the room. I will have the thermal storage in place so it gives me options to run several different ways. I like options, shifting from one heat source to another depending on the season and outdoor temps allows greater efficiency but a larger investment upfront.

OzSolar said:

At risk of being labeled the "expert" (I'm not) I can stay I've been around this stuff for a long time and I've yet to see a sand and/or seasonal heat storage project that really panned out. To be honest I think many were purposely designed to relieve investors of thier money or garner government grants knowing full well they wouldn't pan out.

Click to expand...

They use under ground insulated box with rocks thermal energy storage for the experimental high pressure air "energy storage" facilities. Because they need to retain thermal energy when pressurizing air and heat it back up when releasing it.. This is on large scale though

Both water and stone are already in use. In Belgium for example the 'brick' heaters used to be pretty common, warm them up overnight (cheap tariff) and slowly discharge the heat during the day. In other countries they are less common.

Main stone types are soapstone or clay tiles

More info about this subject: https://en.wikipedia.org/wiki/Storage_heater

In Belgium they are called 'accumulatiekachels' (you can google that), identical to the Britisch ones @Crowz was referring to.


Water storage is also available/tested. Here in NL there are 2 'known' companies to have an actual product available:
Solar freezer -> Many houses here in NL have a basement, which isn't really a basement, but just a 50-100cm space below the surface which also runs plumbing and utilities (mainly gas/water).
The Solar freezer is basicly just a massive waterbed.. a bag which contains.. water.
Its not a self-running system, it just is a cheaper alternative to a ground-bound heat pump. Drilling the required holes isn't always possible/affordable/allowed, so this system uses the water as source for a heatpump (Which is more effective than a air-bound heatpump in the winter)

Another commercially available set is the Borg T4. This is similar to the Solar freezer, however its put in the garden with its own insulaton

gotbeans said:

They use under ground insulated box with rocks thermal energy storage for the experimental high pressure air "energy storage" facilities. Because they need to retain thermal energy when pressurizing air and heat it back up when releasing it.. This is on large scale though

Click to expand...

Please elaborate. Links?

DJSmiley said:

Both water and stone are already in use. In Belgium for example the 'brick' heaters used to be pretty common, warm them up overnight (cheap tariff) and slowly discharge the heat during the day. In other countries they are less common.

Click to expand...

Myself and other's on this forum are doing just that and we aren't challenging that it can be done. I've been doing it for 30+ years in fact. It's when people start talking about 550c or higher temps like it's commonplace with materials available today that we start asking questions. No answers yet.

OzSolar said:

Please elaborate. Links?

Click to expand...

Not sure where to find info, I've worked on site of 1 place.

It's called https://en.wikipedia.org/wiki/Adiabatic_process

There are many links not gonna read them all

This video had a chapter with it and is about air compression:
he talks about it at 4:30
at 7:15 - 9:00 has good info too about the process
The cars in the video seem to have had prototypes for like 15 years but are still not really existing... so I'd ignore that part of the video if you're even interested in compressed air to begin with lmao

As far as I know all compressed air energy storage facilities are still basically experimental stage, pretty sure some are actually attached to grid though unlike experimental things like tokamak ITER in europe

although its certainly low tech, dont earth structures store heat for the cold periods later in the day and im sure i saw on tv once, that some off grid homes (self built) use oil drums full of water as walls, gaining heat in the daytime and releasing it in the night time.

as ever though, some people try to use low tech solutions where there may be better options. mainly because low tech usually means low cost ....

MisterB1959 said:

although its certainly low tech, dont earth structures store heat for the cold periods later in the day and im sure i saw on tv once, that some off grid homes (self built) use oil drums full of water as walls, gaining heat in the daytime and releasing it in the night time.

as ever though, some people try to use low tech solutions where there may be better options. mainly because low tech usually means low cost ....

Click to expand...

Yea basic thermal mass.
homes in USA are insulated with very little thermal mass so internally they heat/cool very quickly.
If you have lots of thermal mass (barrels of water, for example) it takes a long time to heat/cool

so, during winter, if you heat it higher during hottest part of the day or ideally heat with the sun it takes less energy. So at night when you'd have to use less energy since it'll retain heat
opposite in summer
cool it as cold as you can (ideally at night) and it'll take a long time to heat up thus keeping the area cooler

Many places on earth can do a simple open/close windows during fall/spring and have zero heating/cooling for a few months of the year. If you have lots of thermal mass you can extend that to more months of the year... You'd want some fans/pumps to help circulate it faster though. 5-7AM usually coldest part of the day

In New Mexico, adobe bricks have been used for a long time. Technically we are storing heat in bricks. The sun heats the ones by the south window, wood stove heats the others. It helps but is not the solution in of itself.

Adobe homes have no wall insulation traditionally. Living at a higher altitude with cool nights can work quite well in the summer. Winter time requires heating (passive solar, fuel or wood) pretty much all of the time. Those people who just occasionally visit their adobe homes in the winter will need quite a bit of time heating it to make things comfortable other than standing in front of a roaring fire.

Yep good thermal mass and radiant / convection heat
There are some new earthen/green house designs with block/metal exterior, heavy insulation, and then block/brick interior. Keeps it very efficient

High thermal mass works very well if you live in an area where its scorching hot during the day, and freezing cold at night.

That is often the case in desert areas that are a long way inland, or at high altitudes.
The ultimate thermal mass dwelling might be an underground home or a cave.
There is a whole entire mining town in Australia that is pretty much all underground, that is Coober Pedy.
https://en.wikipedia.org/wiki/Coober_Pedy

KITROBASKIN said:

In New Mexico, adobe bricks have been used for a long time. Technically we are storing heat in bricks. The sun heats the ones by the south window, wood stove heats the others. It helps but is not the solution in of itself.

Adobe homes have no wall insulation traditionally. Living at a higher altitude with cool nights can work quite well in the summer. Winter time requires heating (passive solar, fuel or wood) pretty much all of the time. Those people who just occasionally visit their adobe homes in the winter will need quite a bit of time heating it to make things comfortable other than standing in front of a roaring fire.

View attachment 185582View attachment 185583

Click to expand...

I know this is an extreme example, but my friends and I have an off-grid cabin where it can get down to -40 (C or F, take your pick, they are the same at that point!). If we feel like winter adventure, we will go there on the coldest of days. We often open the doors and windows to warm it up when we first get there since it is roughly the average of day and night temps and is actually colder inside than out at first. Then we get a fire ripping and head to the local watering hole for about 6 hours. Still cold sleeping the first night...

Dave, I know what minus forty feels like, that is dangerously cold.
A few deep breaths can freeze your lungs.
Or it can cause the fillings to fall out of your teeth.

fillings used the past ~20 years are porcelain / composite resin and should be fine lol

gotbeans said:

fillings used the past ~20 years are porcelain / composite resin and should be fine lol

Click to expand...

It was about fifty years ago since I was in the Antarctic.
Mercury amalgam fillings back then, which I still have.