Furnaces in forced air heating systems, boilers in hot water systems, fireplaces and space heaters can be fueled by natural gas. It is delivered to your house through an underground pipeline. (It is not available in some areas.)
Most equipment fueled by propane is similar to that fueled by natural gas. In many cases, the only differences are one or two small components that can often be changed by a registered contractor to convert a unit from one fuel to the other. Propane is delivered by truck and stored in a tank on your property.
There are three main types of gas furnaces:
Conventional (with a seasonal efficiency range of 55 to 68 per cent)
Mid-efficiency (78 to 82 per cent)
High-efficiency (90 to 98 per cent)
Gas boilers have similar ranges of seasonal efficiency.
Older conventional gas furnaces and boilers
Some older furnaces and boilers, which are no longer produced but are still in use, require a continuous liner in a masonry chimney or a metal “B” vent chimney. The liner is needed because the combustion gases contain water vapor which condenses on masonry and causes deterioration over time. About 35 per cent of the heat from the fuel goes up the chimney with these models.
Mid-efficiency gas furnaces and boilers
These models remove more heat from combustion gases so that less heat escapes when the gases are exhausted and efficiency is improved. Depending on the circumstances, they might be vented through a wall or through a chimney.
High-efficiency (condensing) gas furnaces and boilers
These models extract so much heat from combustion gases in order to achieve their efficiency, that they can be safely vented through a narrow plastic pipe that runs through the wall.
Gas-fueled fireplaces
Gas fireplaces are sometimes used to provide space heating, though they are often chosen for aesthetic reasons. There can be significant differences in energy efficiency from one model to another, and the effective efficiency of some types can be significantly affected by how they are used.
Oil furnaces and boilers have a burner, a heat exchanger and a blower or pump. Oil is delivered by truck and stored in a tank, which is usually located in the basement.
Older conventional oil furnaces and boilers
Older, conventional oil furnaces and boilers with a standard burner have a seasonal efficiency generally ranging from 60 to 70%. Like older, conventional gas furnaces and boilers, they are no longer produced. However, in an existing model that is working well, the seasonal efficiency can be improved by replacing the burner with a flame retention unit – usually a more cost-effective step than replacing the entire furnace.
New oil furnaces and boilers
A typical new oil furnace or boiler has a seasonal efficiency rating generally ranging from 78 to 86 per cent. Many of these units can be vented through the wall.
Oil stoves
There are free-standing oil space heaters with a visible flame now available. There are no efficiency standards for these products.
Certified Residential and Commercial Inspectors in South Eastern Tennessee & Northern Georgia.