"It holds the heat"

EddyMerckx

I’m pretty sure I know the answer to this but thought it was a good topic for conversation. I have heard people use the term “it holds the heat” to explain reasons why they like a wood stove, cast iron radiator or cast iron baseboard. My response to this has always been "I don’t know why you want a heat emitter to hold the heat”, I would think you would the heat to be out in the room where you are sitting not held within the heat emitter." lol

STEVEusaPA

More mass=holds more heat.

GGross

While the mass certainly will "hold the heat" what most are trying to express when they say that is that they like the feeling of radiant heat. It can be quite difficult to put into words the feeling of different heat sources. You won't really hear too many contractors describe it that way either, because naturally it is not holding it, it is radiating it out in to the room. The best way to decide what you like best is too actually feel some different heat emitters in action

mattmia2

The mass evens out the heat, it continues to radiate heat long after the boiler stops. That makes the temperature more even if the anticipator in the thermostat is set up correctly.

Any heat it holds isn't lost, it has to be transferred to the room eventually. Things with more mass do it over a longer period of time.

EdTheHeaterMan

No No No, everyone has this all wrong, They are talking about all the molecules in the cast iron. each one has little hands that actually HOLD on to the heat!
It's all very scientific!

GGross

@EdTheHeaterMan

Everyone give Ed a Hand! He really outdid himself this time

EdTheHeaterMan

EddyMerckx said:

I’m pretty sure I know the answer to this but thought it was a good topic for conversation. I have heard people use the term “it holds the heat” to explain reasons why they like a wood stove, cast iron radiator or cast iron baseboard. My response to this has always been "I don’t know why you want a heat emitter to hold the heat”, I would think you would the heat to be out in the room where you are sitting not held within the heat emitter." lol

And you thought this was a serious website

EdTheHeaterMan

I must apologize to all those 118 viewers.
I may have been a little quick to post this very scientific information. That molecule was not an Iron molecule. I think it was concrete or some other masonry derivative. Here is the actual Iron molecule over water. It said so in the description. and it is obvious by the color, that it is getting rusty over the water

mattmia2

isn't concrete an ionicly bonded crystal? er, well cement.

EdTheHeaterMan

mattmia2 said:

isn't concrete an ionicly bonded crystal? er, well cement.

That is why I made the correction. Accuracy is of the utmost importance.
No matter how off-topic it may be!

Motorapido

EdTheHeaterMan said:

I must apologize to all those 118 viewers.
I may have been a little quick to post this very scientific information. That molecule was not an Iron molecule. I think it was concrete or some other masonry derivative. Here is the actual Iron molecule over water. It said so in the description. and it is obvious by the color, that it is getting rusty over the water

This pic looks like the cover of an Alan Parsons record from the 1970s. It'll be a chart-topping hit.

ethicalpaul

It also takes longer to heat up before it starts radiating heat

HomerJSmith

More mass=holds more heat.

Not as simple as that. Heat is heat energy. What happens scientifically aside from the little hands is that when energy is applied to a molecule the electrons move from its stable orbit to a orbital ring further from the nucleolus and when the electrons move back to their stable orbit the molecule give off the radiation. That's the way heat energy is transferred.

Some materials are better at this storage and release of energy.

hot_rod

The water content and the weight of the metal, becomes a flywheel. Takes some time to warm, and also emits heat until it cools to the ambient temperature around it.

EdTheHeaterMan

EddyMerckx said:

I’m pretty sure I know the answer to this

After reading all the comments Eddy... Are you sure that you know the answer? Hands on molecules... Flys of Wheels,

EddyMerckx said:

I would think you would the heat to be out in the room where you are sitting not held within the heat emitter." lol

So, maybe a radiator made of fiberglass, or paper would be better. I think I'll try to find one of those stiff cotton boilers to connect them to. I'll need to use @hot_rod Bob's thermal camera to test the results.

This will be a "Joint" effort... because you got to be smokin' somethin' to think this is going to work.

Hot_water_fan

I’m pretty sure I know the answer to this but thought it was a good topic for conversation. I have heard people use the term “it holds the heat” to explain reasons why they like a wood stove, cast iron radiator or cast iron baseboard. My response to this has always been "I don’t know why you want a heat emitter to hold the heat”, I would think you would the heat to be out in the room where you are sitting not held within the heat emitter." lol

I agree. If the boiler is the right size, the water temperature should remain nearly constant over the course of an hour. So what does a heavier emitter provide in that situation?

ChrisJ

Hot_water_fan said:

I’m pretty sure I know the answer to this but thought it was a good topic for conversation. I have heard people use the term “it holds the heat” to explain reasons why they like a wood stove, cast iron radiator or cast iron baseboard. My response to this has always been "I don’t know why you want a heat emitter to hold the heat”, I would think you would the heat to be out in the room where you are sitting not held within the heat emitter." lol

I agree. If the boiler is the right size, the water temperature should remain nearly constant over the course of an hour. So what does a heavier emitter provide in that situation?

Heavy cast iron radiators in a cycling system behave like capacitors in a linear power supply.
They smooth out the pulsing output. Filling in the gaps.

For example, massive cast iron radiators in a steam system that cycles on and off can still provide a nice steady temperature with the proper controls.


In the situation you provided I'm not sure, perhaps no benefit.

hot_rod

energy will always move from an object a a higher temperature to an object of lower temperature.

The rate of the transfer depends on the temperature difference. if you want more heat output from a radiant floor, open the doors and windows

Radiant transfer is line of sight, at the speed of light. Like when the sun comes out from behind a cloud, you feel the energy almost instantly.

ArthurPeabody

Would you want a towel that held the water?
I used to live in a cabin in the mountains. I heated with a wood stove. I didn't get up at night to fuel the fire. That the stove held so much heat made the night more comfortable.

Jackmartin

I dont know about holding the heat come heating season in Winnipeg you will see windows open in every single pipe heating plant. In their case they want the heat to literally stay in the emitters, I have been to blocks seeing some of the ladies wearing beach wear in the middle of January. Strange all these ghoul property managers think spending stupid amounts on gas is just the way it is. I would suggest put all of them together and you might reach a cats IQ, with apologies to cats.

weatherman

I would like to weigh in on this topic.
As I understand it, "holds the heat" is a form of storage or capacitance of certain materials.
The first wave of energy transfer to this material would be conductance and radiation from the original source of energy.
As this energy is stored in this material any difference in temperature would cause energy to be emitted via radiation and conduction from that material.

Lance

Ya know what holds heat? A Hot Potato. It never seems to cool fast enough for me.

ronewold

This is exactly why I love my wood stove- it holds the heat! The last thing I want is to have the heat all over the kitchen floor. That's dangerous and smoky.

ChrisJ

ronewold said:

This is exactly why I love my wood stove- it holds the heat! The last thing I want is to have the heat all over the kitchen floor. That's dangerous and smoky.

Your comment made me think of this.

EddyMerckx

I guess this was a good subject for good conversation. Ultimately I think people like the "radiant" heat of what a cast iron radiator or cast iron base board can provide and in the cast of a wood stove it becomes a situation of liking the radiant heat it gives off along with not having to get up in the middle of the night to restoke the stove.

ChrisJ

EddyMerckx said:

I guess this was a good subject for good conversation. Ultimately I think people like the "radiant" heat of what a cast iron radiator or cast iron base board can provide and in the cast of a wood stove it becomes a situation of liking the radiant heat it gives off along with not having to get up in the middle of the night to restoke the stove.

I suspect most of the stored heat in a wood stove would be in the brick not the thin sheet metal. I guess some may have cast doors.

BradHotNCold

Here I thought this was a serious business but find more Heat energy generated by molecules of laughter!

scott w.

If you had radiators of all the exact same size, one made of glass, one made of plastic, one made of steel, one made of aluminum, one of carbon fiber and one made of cast iron, which would radiate heat the longest?

mattmia2

It is between the cast iron/steel and the glass, assuming they are all the same thickness, probably the glass.

JK_Brown

I have recently watched a couple videos on "sand" batteries. Using sand as a store for heat generated when rates are low then extracting it later reaching temps near 500F. A couple efforts for industrial scale in Europe. That wood stove would "hold heat" better if it had a dry sand jacket to hold the heat, but would be slow to get started warming the room or people.

ChrisJ

JK_Brown said:

I have recently watched a couple videos on "sand" batteries. Using sand as a store for heat generated when rates are low then extracting it later reaching temps near 500F. A couple efforts for industrial scale in Europe. That wood stove would "hold heat" better if it had a dry sand jacket to hold the heat, but would be slow to get started warming the room or people.

Why would a dry sand jacket work better than the bricks they have?

fentonc

This property is called 'specific heat capacity' (how much energy is involved to raise/lower the temperature by 1 degree) and is really well characterized for pretty much everything:
https://www.engineeringtoolbox.com/specific-heat-solids-d_154.html

In units of KJ/(kg-K):

• Brick: 1.0
  
• Dry sand: 0.8
  
• Copper: 0.39
  
• Glass: 0.84
  
• Iron: 0.46
  
• Water: ~4
  

If you want to get it hotter than the boiling point of water, sand is probably just cheaper than brick if you need a lot of it, but brick does seem to have about 25% higher specific heat capacity than sand by weight.

Bulldog8265

I just wish steam and hot water boilers would "hold the heat" when I am cleaning one in a small boiler room in 90 degree 60% humidity day!!!!

HEATSPEC

AS AN OVERSIMPLIFICATION:
HIGH mass is generally desirable for emitters, as it evens out the radiation for a longer period, adding to comfort.
LOW mass is generally desirable for absorbers [boilers, thermal solar panels, etc.] as it generally makes for a higher delta T and thus quicker absorption of heat from the generating source.