Heating

As we reach mid-October the nights have started to become chillier, with sub-40F for the first time since we've been in this house. As a consequence we've started using the central heating, which leads me to make a few comparisons with UK heating systems.

The majority of UK houses are heated via a boiler and radiators. The boiler (usually fuelled by gas or sometimes oil) heats water is a semi-enclosed system, which then circulates round the various radiators in the house. The radiators slowly heat up from the water, and whenb theyv are good and hot (hot enough to be uncomfortable to touch) transmit heat to the air in contact with them. The heated air then circulates by convection, and eventually the whole room is warmed. Some heat is transmitted directly to the room by radiation (hence the name), but not much.

All that takes time, so it takes 20 minutes to half an hour before the air in the room starts to feel warmer.

In a typical US house, a furnace (usually located in the basement or garage) heats air directly, which is then circulated round the house via hidden ducts under the floors, behind walls and ceilings. Instead of radiators, which take up space and prevent the placement of furniture against walls where a radiator is located, there are flat grills on the floor, wall or ceiling, which vent air into the room. In strategic locations there are also exhaust vents which carry air out of the room to ensure good circulation.

As the final target is to have warm air in the house, it seems a much more efficient method to heat the air directly, than to heat water to heat radiators to heat the air.