1. Heating Systems 2 nd law of thermodynamicsheat always flows from a hotter to a colder substance

4. 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) Winterindoor temperature is greater than outdoor temperature (flow is from inside out)

5. Commom Fuel Sources for Heating Wood Coal Oil Natural Gas (methane) Methane CH 4

6. Pre-Mid 1700s Open fire Fireplace with brick Fuel Source: wood

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

8. 1885-1900 Coal Boiler Natural convection (no electricity for pumps) Fuel Source: coal

9. 1900-1930s Coal Boiler Circulated water or steam to radiators Fuel Source: coal

10. 1930s - 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

11. 1950s -- Trend towards forced air heating systems to accommodate central air conditioning Fuel Source: forced air heating(natural gas) Air conditioning (electricity from coal)

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

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

14. 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