The cost of natural gas has increased by 65% in the fall of
2000 but it is still the most economical and cleanest burning fossil
fuel. Here is how much more it will cost you to heat your home with
other energy source compared with natural gas:
| OIL |
27% |
| ELECTRICITY |
50% |
| PROPANE |
55% |
Heating Systems
The heating system includes four main components:
-
The heating unit (such as a furnace or
boiler) supplies heat.
-
The distribution system moves heat from the
heating unit to the living space. Some systems, such as electric
baseboard, supply heat directly without a distribution network.
-
The fuel provides energy to produce heat.
-
The controls regulate the system - for
example, the thermostat turns the system on or off to keep the house
at the desired temperature.
Heating Units
- a furnace provides heat to a forced air
distribution system.
- a boiler provides heat to a hydronic or hot water distribution
system.
- a space heater (e.g. gas fireplace) supplies heat directly to
the room where it is located.
These have no central heating unit or distribution system.
There are three main types of gas furnaces: conventional
(obsolete), mid efficiency and high efficiency. Seasonal efficiency
ranges from 55% to 65% for an older conventional furnace; from 78% to
82% for a mid efficiency furnace; and from 90% to 98% for a high
efficiency furnace. Natural gas boilers have similar ranges of seasonal
efficiency.
Conventional, sometimes referred to as
older gas heating units require a continuous, fire resistant liner in a
masonry chimney or a metal type 'B' vent (a pipe through the roof).
Combustion gases - including water vapor and carbon dioxide - are vented
through the chimney, but some heat escapes as well.
Some mid efficiency models do not require
a chimney. Instead, they use an electrically powered fan (or induced
draft) to force the exhaust gases through a vent to the outdoors. Much
of the heat that would have escaped through the chimney is saved.
A high efficiency furnace goes one step
further by extracting more heat from the hot gases before they are
exhausted. Water vapor, in particular, holds a substantial amount of
heat. The high efficiency model feature a stainless steel heat exchange
surface, so water vapor can be condensed and more heat captured. Some
condensing furnaces are equipped with a fan to vent the exhaust out of the
wall through a narrow plastic pipe.
Distribution Systems
Forced Air: Virtually all new homes and most
older homes have forced air distribution. A forced air system is based
on a network of ducts linking all rooms in the house. An air circulation
fan in the furnace forces warm air from the heating unit through
the duct work to the rooms. Registers in individual rooms can be
adjusted to control air flow. Cold air registers (returns) in the rooms
draw air back through separate duct work to the furnace. A forced air
system delivers heat quickly. It can circulate air continuously, and it
is ideal if central air conditioning or air cleaning is desired.
Hydronic: Hydronic or hot water distribution is
most often found in older homes. A hydronic system is based on a network
of pipes that carries heated water from the boiler to radiators in each
room. In modern installations, the water is circulated by a pump.
Today's hydronic systems also feature compact boilers, narrow copper
piping and stylish radiators. Hydronic systems may also be installed in
the floor.
