The radiators around your house are there to heat your house. So why are you heating the street then!
First some explanation of heat loss theory. If the outside temperature is 0oC an the temperature inside is 20oC, the heat energy will try to move from areas of hot towards cold - it tries to equalise over time. The higher the inside temperature, the greater the temperature difference and therefore more energy tries to move towards the cold areas.
The walls in your house act as a barrier to the flow of heat inside towards the cold outside. If they are well insulated, the time taken for the heat to leak towards the cold outside is longer. The glass in windows is a poor insulator compared to the walls, so the heat is lost through the windows escapes quicker than through the walls.
Now we have established the basics, we need to think about radiators. They too work on the same rule that heat energy moves from hot to cold areas. The temperature in your room is not uniform. The radiator is likely to be around 60oC and it loses some heat in order to heat up the room. Objects such as walls near the radiator will be hotter than objects further away as they have absorbed more heat from the radiator. In areas where the heat loss is higher, will be colder - this is why standing near the windows will feel colder than standing in the middle of the room.
Plumbers used to put radiators on outside walls and under windows. So the outside wall, which is close to the radiator gets heated to maybe 35oC whereas the temperature in the room is only 20oC. The heat rising from the radiator is near a window so the heat energy escapes through the window. Using our heat loss theory rules, it is easy to see that the heated exterior wall behind the radiator will be losing more energy than the exterior wall a few feet away from the radiator.
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So what can we do about this? Well a simple thing is to buy reflective insulation to put behind the radiator. Rather than heating the exterior wall, the heat is reflected back into the room and hence reduces heat loss. Although this insulated foil is only thin, some types of it are equivalent to 55mm of polystyrene insulation so are highly effective at stopping this wasted heat. A more disruptive but effective solution is to move your radiators so that they on internal walls. Whilst doing this, thermostatic radiator valves can be installed. If you are a competent plumber, this shouldnt be an expensive activity to move the radiators but it will be time consuming. The ease of doing this will be heavily dependent on your existing pipework. This will stop heating up external walls and in addition if the radiator was under a window, will reduce the heat leakage through the window. The insulating foil should save about 40W per hour for a radiator 1m x 1m. Assume we have 30 days per year where the outside temperature is 0oC and you have the heating on 10 hours per day on these days, you will save about 70p per radiator per year. A roll of the foil from screwfix costs £7.33 for 2.5m x 50cm. Based on current energyprices and using gas heating the roll should save about £1.75 per year so will pay for itself in 4 years. |