Monday, January 4, 2010

Home Heating - Natural Convection Systems

Natural Convection Systems
These have warm air rising automatically from heaters because it is less dense than the air
around it. As in a chimney the natural convection draws more cool air into heaters to keep the process going.

The warmed air rises to the ceiling with little mixing With cool air. It loses heat to the ceiling somewhat as it fills the upper part of the room. Then it gradually descends as it is replaced by warmer air following it. Eventually it arrives where people are, 0-6' above the floor with little mixing with cool air along the way.
All shielded stoves and baseboard heaters work this way. And if they are not shielded they will lose some heat by radiation continuously and less will be carried by natural convection.

No electricity will be used to raise the warm air.
The whole room is heated eventually by the warm air at the ceiling slowly moving down.
No drafts are created.

Slow response when starting and stopping.
Warm air gets to the cool ceiling and it loses some heat to it.
It creates uneven temperatures where people are 0-6' above the floor.
It makes for cold floors.
If baseboard heaters are used they will need regular cleaning and they are successively harder to clean. This makes for increasing inefficiency throughout their lives.
Baseboard heaters should not be under any furniture. For this reason they limit the use of the space along walls.

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