Introduction to heat • Is this heat? • When I touch it, it burns me. • I can feel the heat at a distance • The hot gases rise
Dec 18, 2015
Introduction to heat
• Is this heat? • When I touch it, it
burns me.• I can feel the heat at
a distance• The hot gases rise
But is this heat?
• Yes • The difference
between the two is Temperature
Any substance whose temperature is above -276 degrees celsuis or -460 degrees Fahrenheit contains heat
Whether something is hot or cold is subject to your preconceived
experience
• When we see blue we tend to think cold
• When we see red we tend to think hot
HVAC and R
• H is for heating
• V is for ventilation
• AC is for air conditioning or cooling
• R is for refrigeration
Heating
• Increasing temperature from an intensity that is felt as too low to a comfortable intensity
• This can be accomplished by combustion of a chemical that releases heat
• Moving of heat from one place to another
• Convincing the person that they are actually warm
Air Conditioning
• This is a little more complicated
• Air conditioned air is generally considered cooled air.
• Its humidity is also changed when it is cooled so it is considered conditioned
Refrigeration
• Refrigeration is generally considered as temperatures below human comfort
• First used to extend perishable food life
Heating Technology
• Technologically, heating is far easier than cooling
• The first forms were wood fired campfires around which everyone sat to be warmed
Advantages
• Easy to start if you had something hot and it had not rained lately
• Fuel was easy to find
• Fire looks cool
Disadvantages
• Was not self sustaining
• Smoke always followed you wherever you sat
• Rain had a dampening effect
• You were always cold on the side opposite the fire
The same temperature as the outside air which is why the
other rooms in the structure are very cold after the fire has been
burning for a while
The Franklin Stove (invented by Ben Franklin) covered the
majority of the open area that removed so much air and only allowed enough air to support
combustion
We have developed a stove that is reasonably efficient that can
heat a structure. Is this the best system for heating?
What if there are more than one room in the house?
• The temperature in the room with the stove will be warm
• All other rooms will be progressively cooler the farther they are from the heat source