2. HEATING SYSTEMS

3. Questions Why do we need heating systems? What was the first heating system? Which types of energy do you need to operate today’s heating systems?

4. How is the human body like a heating system? Purpose of a heating system Comparison of components in a radiant heat system vs. the human body Seasonal heat flow associated with your house and your body Purpose of insulation

5. Desert Cottontail—how does the rabbit shed excess thermal energy? http://k43.pbase.com/o6/50/493350/1/81965672.V6 e9SMLr.DesertCottontail7907web.jpg Fur keeps the rabbit warm at night Ears serve as heat radiators (see blood vessels)

6. Function of a heating system 1.Burn a fuel 2.Heat a fluid (air or water) 3.Circulate a heated fluid 4.Transfer thermal energy into a space o By convection, conduction and radiation

7. Heating System Any device or process that transfers energy to a substance to raise the temperature of the substance.

8. The problem: HEAT FLOW FROM HOUSE During cold days

9. Three thermal energy transfer methods in action.

10. Different types of heating systems Radiant heating system Forced-air heating system Wood stove Fireplace Heat Pump Circulation of geothermal fluids

11. Radiant Heat System Where does the thermal energy go?

12. Forced-air Heating System

13. Solar Heating System

14. Wood Stoves

15. Geothermal Heating Systems

16. Do you see where thermal energy is added to a fluid and can you find the exhaust?

17. http://www.hometips.com/hyhw/comfort/38comf.html http://www.woodfloorsonline.com/techtalk/woodwater7.html http://www.greenenergy.org.uk/sta/solarenergy/howwork.htm http://www.diydata.com/projects/centralheating/balancing/balancing.htm http://www.northridgevillehistoricalsociety.org/images/schoolinnorthw.jpg http://www.totalcomfortnc.com/geo.htm http://www.igshpa.okstate.edu/geothermal/geothermal.htm

18. Heating Systems 2 nd law of thermodynamics—heat always flows from a hotter to a colder substance

21. Explain why the heat flow for a home is different in the winter vs. the summer. Summer– outdoor air temperature is greater than indoor air temperature (flow is from outside in) Winter—indoor temperature is greater than outdoor temperature (flow is from inside out)

22. Commom Fuel Sources for Heating Wood Coal Oil Natural Gas (methane) Methan e CH 4

23. Mid-1700’s to 1800’s Fireplace with brick Franklin iron wood stove Fuel Source: wood

24. 1885-1900 Coal Boiler Natural convection (no electricity for pumps) Fuel Source: coal

25. 1900-1930’s Coal Boiler Circulated water or steam to radiators Fuel Source: coal

26. 1930’s - Radiant Heat and Forced Air Heating Systems Circulated “heated” water or steam to radiators and “heated” air through ducts to registers Fuel Source: natural gas and oil

27. 1950’s -- Trend towards forced air heating systems to accommodate central air conditioning Fuel Source: forced air heating(natural gas) Air conditioning (electricity from coal)

28. Burn a fuel Heat a fluid Circulate a heated fluid radiator Water- filled pipes Radiant energy 90 F 150 F Radiant Heating System

29. Burn a fuel Heat a fluid Circulate a heated fluid convection Forced-air Heating System (can be adapted to central whole-house air conditioning)

30. Convection, Conduction or Radiation? 1.Stick in campfire 2.Hot air balloon rising 3.Hot concrete surface at pool 4.Lizard sunning itself on a rock 5.Pan of soup warming on the stove 6.Foot on cold tile floor Conduction Convection Radiation Convection Conduction