# In a normal fireplace with normal wood, on average what temperature would a plate be under the burning wood?

Discussion in 'Highly Technical' started by superHARD, Dec 27, 2006.

1. ### superHARD Diamond Member

Joined:
Jul 24, 2003
Messages:
7,828
1
Kind a long question, but if you put a plate under a burning log in a fireplace, how hot would that plate get?

#1

2. Similar Threads - normal fireplace normal Forum Date
Is electric charge in new TV body normal? Highly Technical Dec 12, 2016
is square root of 2 normally distributed? Highly Technical Aug 31, 2016
Low Voltage ram on a normal laptop? Highly Technical Oct 2, 2015
Why is the normal distribution of such importance to statistical models? Highly Technical Jul 25, 2010
How does one interpret values that are normalized with respect to multiple parameters Highly Technical Mar 14, 2010

3. ### oynaz Platinum Member

Joined:
May 14, 2003
Messages:
2,442
0
Does the log touch the plate? What is the plate made of?

#2
4. ### superHARD Diamond Member

Joined:
Jul 24, 2003
Messages:
7,828
1
Yes it touches the plate.

Metal plate

#3

Joined:
Jul 24, 2003
Messages:
7,828
1
#4
6. ### CycloWizard Lifer

Joined:
Sep 10, 2001
Messages:
12,352
0
I would think that it would depend on the type of wood, as the chemical composition of woods differ considerably. The 1500°F neighborhood sounds like it's in the right ballpark though.

#5
7. ### TheoPetro Banned

Joined:
Nov 30, 2004
Messages:
3,500
0
does the mass of the log come into play here? I would guess it would matter the type of material the plate is, the type of wood, the mass of the plate, air currents, volume of fireplace, and mass of wood.

#6
8. ### Megamixman Member

Joined:
Oct 30, 2004
Messages:
150
0
I think the mass of the wood would only come into play only under the circumstance where it is not enough fuel to put the plate into thermal equilibrium. I don't think we need to worry too much about the chemical composition of the wood, but more so rather the material that the plate is made of.The mass of the plate is important; the volume of the fireplace would be important if it could act as a restricting factor in the airflow.

#7
9. ### superHARD Diamond Member

Joined:
Jul 24, 2003
Messages:
7,828
1
1000-1500 F is my answer...at least it's close enough.

If your leaving a plate in a fire, why does it matter what the plate is made of (as long as it would burst into flames or something)?

#8
10. ### Cogman Lifer

Joined:
Sep 19, 2000
Messages:
10,117
19
I was going to try and refute you but really its a good point. The only problem is if you have a material like clay then it wont get as hot as metal would before the log completly burns out. however with metal the tempatures should stay roughly the same with little to no variation. The main question is what kind of wood do you have as diffrent material burn at diffrent temps as well the construction and aid of devices like catalitic converters all play a role in how hot.

#9
11. ### wwswimming Banned

Joined:
Jan 21, 2006
Messages:
3,712
1

when i started making jewelry i did it the "old-fashioned" way,
using iron molds in an oak or pine fire.

i had only 2 successes. the mold was in the shape of a cross.
the pellets i used melted completely into the shape of a cross;
the top is kind of rounded.

silver melts at about 1700 F i think.

the oak fires worked better than the pine fires (hardwood
burns hotter than softwood.)

#10
12. ### foges Senior member

Joined:
Mar 28, 2005
Messages:
324
0
Material of plate has no effect on final temperature, only on time and amount of wood needed to heat the plate.

Does wood have a specific temperature at which it will always combust (ie no varience)? or can it go to infinity if you varied the factors such as:
Efficiency/rate of combustion of wood
Chemical structure

So if you combusted wood super efficiently (tons of oxygen, lots of surface), it would just release an large amount of energy which would the be distributed in its surroundings and with more energy comes more heat.

#11
13. ### bobsmith1492 Diamond Member

Joined:
Feb 21, 2004
Messages:
3,870
1
We had a fire once where it melted the glass out of our fireplace doors...!

I came home and there were two big blobs where the windows had been. Fortunately, someone was home to move the table and furniture away. I think it was a massive birch stump (not split) we were burning.

#12
14. ### WHAMPOM Diamond Member

Joined:
Feb 28, 2006
Messages:
7,134
60
Metal conducts and absorbs heat easily. Ceramics won't, insulator
I would guess 500 degrees tops. Not enough to get red hot, since heat rises and the incoming draft feeding the flame would cool the plate.

#13
15. ### cougar1 Member

Joined:
Dec 5, 2006
Messages:
31
0
For an upper limit, you can use the adiabatic flame temperature. This is a theoretical number calculated by assuming that all of the heat produced by combustion goes into heating just the combustion products (the gases released upon combustion) with no losses. Essentially, this is the highest temperature that can possibly be achieved anywhere within the flame. According to http://www.doctorfire.com/flametmp.html , the adiabatic flame temperature for wood is about 1977°C. In reality this number will depend a bit on the type of wood and especially the moisture content (higher moisture leading to lower temperatures).

For your situation the temperature will be significantly lower, as most of the heat will be carried up through the chimney with the combustion gases and a significant amount will be radiated out into the room surrounding the fireplace. According to the reference above materials in housefires usually are below 1093°C, so even this would be a safe upper limit. As for the lower limit, that depends a lot on the materials involved, duration of the burn, and many other factors. In the extreme case of burning the top surface of a relatively thick log, the temperature may never get much above room temperature, since the log will essentially block any heat transfer to the plate below.

#14
16. ### StopSign Senior member

Joined:
Dec 15, 2006
Messages:
986
0
Guys, let's stick to Centigrade here. None of that Fahrenheit stuff.

#15

Joined:
Jan 11, 2000
Messages:
3,383