Principles of Heat in Plumbing Systems PDF

PowerPoint 4 Principles of heat in relation to plumbing systems LESSON INTENT All will be able to describe the different principles of heat transfer Describe the different situations where we will encounter the different heat principles within a system Leaners will be able to distin...

PowerPoint 4 Principles of heat in relation to plumbing systems LESSON INTENT All will be able to describe the different principles of heat transfer Describe the different situations where we will encounter the different heat principles within a system Leaners will be able to distinguish the best materials for conducting heat  PRINCIPLES OF HEAT Heat transfer There are three methods by which heat can be transferred: Conduction Convection Radiation  TRUE OR FALSE QUESTIONS! If you heated a bit of copper pipe and you was holding the other end would the heat transfer into your hand? TRUE OR FALSEThis = is true the heat would transfer into your hand through conduction Heat travels around a room the heat rises and as it cools it falls this is called convection? TRUE OR FALSE This = is TRUE as the room gets hotter heat rises and the cold air passes through the radiator and the cold air is reheated. Conduction Conduction happens when heat travels through or along a material (one molecule to the next). Heating copper tube to solder, or heating coil in a DHWC. Copper is a very good thermal conductor. Plastics tend not to be good thermal conductors. CONDUCTION NOT ALL MATERIALS ARE GOOD THERMAL CONDUCTORS, AND WE CAN USE THE BAD CONDUCTORS AS INSULATORS. THE FASTER HEAT TRAVELS, THE BETTER CONDUCTOR THE MATERIAL IS. COPPER GOOD CONDUCTOR ALUMINIUM IRON Materials that are GLASS BRICK good thermal WATER conductors are also WOOD POLYSTYRENE good electrical STILL AIR BAD CONDUCTOR conductors. Convection Can only take place in a fluid or gas. Convection occurs when molecules are heated, they heat and rise, and when they cool they fall. This is the main way a DHWC heats the water up by. Radiation This is heat transfer via infrared light. It transfers heat from one body to another without heating the space in between. Heat transfer Heat is measured in 0C or scientifically in Kelvin (K). Certain situations mean that heat needs to be retained – and at other times emitted – but always controlled. Hot water cylinder pipes need insulating to keep the heat in, so the hot water does not lose its temperature (efficiency). Heat transfer Cold water mains pipe needs to be insulated to stop condensation forming on the pipe. White cars are more common in hot countries, as white reflects the sun’s heat. In solar panels, shiny surfaces are needed to absorb the heat from the sun. Dark colours absorb heat – unpainted cast iron. Light colours reflect heat – polished aluminium. Heat remains in the pipework when it is insulated and therefore increases efficiency and reduces running costs. Needs to be controlled: Building Regs part L. Programmers – only on when needed. Boiler stat – not too high (primary circuit). Cylinder stat – not above 600C (secondary circuit). Room stat – as low as possible. TRVs – control individual rooms. Zones – upstairs and downstairs. City and Guilds 6035 Level 2 Unit 201 CHECK YOUR KNOWLEDGE WITH THESE QUESTIONS. 1. What is conduction? 2. What is convention? 3. What is radiation? 4. What metal is the best conductor of heat? 5. What is heat transfer? TRAFFIC LIGHT IT: WHERE IS YOUR LEARNING AT? Red = I have not really understood the content we have studied today (write down 2 questions that you need help with) Amber = I have understood the content on Effective Questionning (write down 1 one question you need to clarify) Green = I have understood all the content (write down one example from what we have studied)