Heating one's home has been done by ages by many difference methods. At the turn of the century older homes used parlour fireplaces and also used wood or coal to heat individual rooms.

As more advanced mechanical systems appeared, gravity systems using air as the mover of heat via convection became more common.

Some of you may remember growing up to the "monster" box in the basement with large pipes going up to large cast-iron floor grates usually in the floors but sometimes in the walls. Early systems relied on coal. hand-fed then later ones using oil burners became more popular.

Eventually toward the middle of the century gas became more popular. As lanes were laid in the ground the gravity systems with oil burners were replaced with gas conversion burners, then add-on blower units were added to make them more efficient. Following these millivolt versions of the modem furnace appeared finally evolving in the 1960's to the standard control system voltage of 24 volts, which controls the modern furnace operation.

Standard Efficiency

Furnaces available up to the early 1990's were pilot operated meaning they had a pilot light wasting fuel all the time.. They also had a draft hood which allowed air to leak up the flue all the time causing heat loss in the house. They were — 60-65% efficient.

Mid-Efficiency Gas Furnaces

Were introduced in the 1980's and. have totally replaced draft-back type furnaces with pilot Iites. These furnaces have a more advanced heat exchanger that results in higher efficiency and inducer fan which controls combustion & flame in the burners. Electronic ignition means there is no wasteful pilot lite and average efficiency is – 80%. They are ideal where a customer wishes toy upgrade an old furnace. has a smaller house, may be moving soon in future and wishes to have a new furnace to increase resale value.

These furnaces originally were allowed to be side wall vented using special pipe & sealant. However many installations failed resulting in carbon monoxide poisoning. The regulatory authorities decided to ban this pipe and also mandated that existing systems be retro fitted to a chimney system. As a result today all mid-efficiency furnaces must be' vented either into an approved chimney venting system or a masonry chimney that has the correct sized lines for the furnace and a water, heater if both are vented into it.

Mid-efficiency furnaces are declining in popularity partly because natural gas has increased in cost considerably and also that there are no incentives from the gas company to install them. Expect to eventually see them discontinued which will leave the most efficient furnace option

High-Efficiency Gas Furnace

Lennox first developed this product in the 1980's with the introduction of the "Pulse" furnace. It had, efficiencies of over 95% and was quite reliable. The original G14 Series was replaced with the new G21 Series in the 1990's. Early models had' problems with some heat exchangers. Please call us if you have one of these furnaces and have not had Lennox test it for more information.