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Definition

FURNACES: Samuel E. Forman, in his 1911 book, “The Stove,” Stories of Useful Inventions, defined the furnace as a large stove placed in the cellar from which pipes ran to all the rooms of the house.

A century and a half of furnace manufacturing

1. Image of a coal-fired furnace

1. Gravity furnace from 1887.
Click the image for more information.


Over the past 150 years, the furnaces used to heat homes have improved immeasurably. The early ones were made of cast iron and were prone to leaking their noxious products of combustion, such as carbon monoxide. Most were also fueled by coal, which was dirty and dusty, and they needed attention from homeowners several times a day. Today's furnaces are made of steel and computer controlled, and require no more human intervention than an annual service from a technician.

However, early furnaces did offer advantages over wood and coal stoves, and fireplaces. A single unit could be tucked away in the cellar and provide warmth to the whole house, and they had few moving parts so they lasted many decades. The fuel they burned generated warm air that rose naturally through convection because warm air is lighter than cold air. This was the reason they were called gravity furnaces.

The many ducts that sloped upwards from gravity furnaces in all directions earned them the nickname “octopus” furnaces. The ducts carried the rising warm air into each room of the house. Meanwhile cold air was displaced by the warm air, gradually sinking (through the force of gravity) to the floor where it was collected by ducts at the base of the walls that returned it to the furnace to be reheated.

As they became more widely available, oil and gas began to replace coal as the fuel of choice, reducing the labour homeowners had to put into their furnaces. As well, thermostats that raised and lowered temperatures and other controls improved and became increasingly automatic reducing the labour involved in keeping a home comfortable. Then, in the mid-1930s fans were attached to furnaces and forced-air heating was born.

Forced-air heating improved efficiency and helped keep temperatures uniform throughout the house. Also, constant air circulation, air filtration, and humidification became possible.

Section Gallery

2. Cutaway view of an oil-fired, forced-air furnace3. Ad promotes the heating power of a Garnet furnace4. Diagram of a high-efficiency-condensation-gas-furnace

5. Photo of a modern furnace6. Image of a gravity furnace made by Grimsby Stove and Furnace7. Advertisement for an early gas-fired warm air furnace

Factually Speaking

In 1895 two inventors, Ernest Bryant and Ezra Smith, engaged a machinist, Dave Lennox (founder of what is now Lennox International), to build a riveted steel furnace that would address problems with cast iron such as cracking and warping, which could lead to leakage of flue gases.

The early 1900s gravity warm air furnace

1. Image of an arc-welded steel warm-air furnace

1. The central warm-air steel furnace of the mid-
20th century. Click the image for
more information.


Warm air gravity furnace technology would be good news for Canadian households beginning in the latter years of the 19th century, to enter the mainstream in the early 20th. With the advent of the warm air furnace the principal heat source for Canadian homes would disappear from the kitchen and parlour into the basement.

Missed by many would be the cozy warmth of the late 19th century parlour stove on which many Canadian homes, both urban and rural, had come to depend for their winter warmth and comfort. Like much technology, it “giveth while it taketh away.”

Paradoxically that sense of parlour-stove coziness had been replaced by a wider sense of warmth and comfort throughout much of the home. With the gravity, warm-air furnace many Canadians would take their first steps towards central automatic warm air heating. While imperfect, the gravity warm-air furnace would distribute a blanket of warm air, more or less throughout the house, in a manner not previously imagined.

The effectiveness of the furnace, now tucked away in the basement, depended on a simple principal of science, warm air rises. The upwards movement of warm-air from the furnace to the first and second floors of the home was facilitated by a sprawling network of large round sheet metal pipes, typically 14 to 18 inches in diameter. The cold air would be drawn back to the furnace for reheating by a similar system of cold air pipes.

Section Gallery

Factually Speaking

During the 1930s electrical welding technology increased the speed and quality of furnace manufacture. Source: International Directory of Company Histories, Vol. 37. St. James Press, 2001.

An automatic furnace milestone:
The birth of the “Winter Air Conditioner”

1. Cutaway view of a furnace, with humidification, that ran on coal, oil or gas

1. The “winter air conditioner” of the late 1930s.
Click the image for more information.


Automatic warm air heating, in the form of a “winter air conditioner,” was first marketed in Canada in the mid to late 1930s. When it arrived, it was as a breath of fresh air to a people ready to move beyond subsistence living, huddled around the parlour stove or warm air register.

The winter air conditioner represented a convergence of five advanced technologies of the period: First, a high pressure oil atomizing, gun-styled oil burner, new for the times; second, an automatic control system consisting of combustion, safety, and temperature limit controllers; third, a high volume squirrel cage blower, guaranteeing warm air circulation throughout the home; fourth, air filters; and fifth, a warm air humidifier.

More than just a central warm air furnace, the winter air conditioner was a total “system.” The system, with many component parts, would generate heat automatically and distribute it throughout the home, changing the air several times each hour. The system would include new high tech streamlined duct work, for distributing warm air, register faces for comfortable air delivery to every room, as well as a room thermostat that would maintain temperature within a range of plus or minus 2°F.

The system represented significant advancements in applied science and engineering design, materials development, manufacturing processes, and fabrication methods.

Enclosed in a modern streamlined cabinet, the winter air conditioner could be located in a corner of the basement, freeing space for other uses like work benches and laundry rooms, and a place for leisure and entertainment called the “recreation room.” Beyond its potential for new levels of performance and comfort, the winter air conditioner would be shamelessly promoted as a principal portal to new lifestyle living for Canadians.

Section Gallery

2. Image of an “Oil-o-Miser” oil burner3. Image of an underfeed coal stoking attachment4. Composite image of a filtering, squirrel-cage fan wheel and early humidifier5. Image showing a blower and electric motor

6. Howard Furnace advertisement from 19587. Image of a Hi-boy gas furnace8. Image showing a basement recreation room with a furnace in the corner

Factually Speaking

By the mid-1930s forced-air furnaces were pushing old-style, gravity furnaces out of the marketplace. However, the simplicity and durability of gravity furnaces meant many remained in service for decades to come.

Initial development of the condensing
gas furnace in Canada

1. Diagram of a condensing furnace

1. Diagram of a condensing furnace
Click the image for more information.


In late 1978, the Canadian Gas Research Institute (CGRI) in Toronto, Ontario advised Canadian gas furnace manufacturers it had developed a condensing technology that could potentially greatly improve the efficiencies of gas furnaces. The goal was 90 percent efficiency versus 78-80 percent for mid-efficient models and 60 percent for the old standard furnaces, to match new US condensing technologies.

Three companies signed confidentiality agreements to commit to produce such a product over 1979-80: Inter-City Gas Corp. of Winnipeg via its manufacturing division (Anthes, Bullochs, Furnasman); Clare Brothers, Preston, Ontario; and Clawsey-Short, Galt, Ontario. Little was known of this new technology, and the three participants soon realized CGRI’s condensing technology was not as far advanced as they had expected. The key issues of secondary heat exchanger material, condensate removal, and power venting were far from resolved in CGRI’s project.

Actual furnace design was also left to the participants. ICG and Clare chose the “wrap around” style of oil furnace heat exchangers, and power burners. ICG was the first on the market in 1980 with its “Ultimate” model, and Clare followed with its “Megasave” model, both near 90 percent efficiency ratings.

Unfortunately, for the manufacturers, the Canadian industry and initial customers, the first and second generation of these appliances were fraught with problems. They eventually disappeared and were replaced under licensing agreements by successful U.S.-designed units. The unresolved problems in those early Canadian-made condensing furnaces were still secondary heat exchanger failure; lack of knowledge of and product for condensate removal; the appliances’ physical dimensions; and premature failure of the power exhaust gas venters selected.

One Canadian manufacturer which did have early success with its own “Ultramax” condensing model was Duomatic Olsen of Wallaceburg, ON. The American “invasion” had a Bryant model using a variable speed fan in 1981, Lennox in 1982, and the other brands followed — the high efficient era was underway, and is now the dominant gas furnace in 2010. Changes in technologies take time to transfer — as it was over the previous 130 years.

Section Gallery

Factually Speaking

High-efficiency gas furnaces first became available in the early 1980s.

The trials of developing a
condensing oil-fired furnace

1. View inside a condensing oil-fired furnace

1. View inside a condensing oil-fired furnace.
Click the image for more information.


With the gas heating industry growing with 90 percent efficient condensing gas furnaces, oil heat’s need for an oil-fired condensing furnace became obvious. Inter-City Gas, a utility, and Anthes, its manufacturing division in Winnipeg, Manitoba, contracted with Eneroil Research Ltd. of Toronto, Ontario in the early 1980s to find a design solution. However, the high price of oil and the federal “off-oil” program convinced ICG to focus on gas heating.

Eneroil’s engineer Robert Smith continued to develop the technology on his own. That research and development had begun with a gas furnace heat exchanger developed by Anthes. Smith designed an atomized water scrubbing system, Comfort Plus, to capture the heat from exhaust flue gases. The spray system partially flashes to steam, mixes with the flue gases, scrubs the sulphurous particulates, cools the gases to dew point, and dilutes the acidic condensate while cleansing the heat exchanger.

As a standalone condensing heat recovery unit, Comfort Plus had CSA approval in 1984 and could be installed on the cold air return on most rear-breach low-boy oil furnaces or on Eneroil’s Comforter mid-efficient oil furnaces. The unit was field tested by several Canadian oil companies and a US agricultural cooperative.

When Eneroil went into bankruptcy later in the 1980s, its assets were retained by Hunter Enterprises of Orillia, Ontario, which had been manufacturing the units for Eneroil.

Hunter then made several design changes to bring the furnace up to CSA safety standards and make it suitable for manufacturing.

Later, Hunter sold its oil-heat division to Duomatic Olsen in Wallaceburg, Ontario.

Section Gallery

2. Cutaway view of an oil-fired condensing furnace


Article Sources

A century and a half of furnace manufacturing

  • Research from the archives of the HVACR Heritage Centre Canada (DCSB #215)
  • Sources have not been added yet.

The early 1900s gravity warm air furnace

  • Research from the archives of the HVACR Heritage Centre Canada (DCSB#65, HD1008O).

An automatic furnace milestone: The birth of the “Winter Air Conditioner”

  • Research from the archives of the HVACR Heritage Centre Canada (DCSB #4, HD1001M).
  • Howard Air Conditioning Design for Canadian Conditions: Sales Bulletin 38-1, 1938

The trials of developing a condensing oil-fired furnace

  • Research from the archives of the HVACR Heritage Centre Canada (DCSB #103).

Initial development of the first condensing gas furnaces in Canada

  • Research from the archives of the HVACR Heritage Centre Canada (DCSB #49, HD1006G).
  • Author: Dave Tayler, as reported to “Warming Up” in April 2010. He was ICG/Inter-City Gas vice president, manufacturing and supply, Winnipeg, Manitoba, and is now an industry business consultant, Simcoe, Ontario.
  • Bryant Heating and Cooling: www.catalogue.bryant.com/corp.details/.
  • Galt Buying Guides, Online since 1995, via http://www.galttech.com/research.
  • Natural Resources Canada, via www.nrc-crn.gc.ca.

SIDEBAR

  • S.E. (Samuel Eagle) Forman, Stories of useful inventions (New York: The Century co., 1911).
  • Galt Buying Guides, Online since 1995, via http://www.galttech.com/research.
  • Bryant Heating and Cooling, via www.catalogue.bryant.com/corp.details/.
  • Natural Resources Canada, via www.nrc-crn.gc.ca.
  • Research from the archives of the HVACR Heritage Centre Canada.

Image Credits

A century and a half of furnace manufacturing

  • Clare Brothers, Descriptive catalogue of fine stoves, ranges and hollow-ware, of warm air furnaces, registers and combination heaters, 1893-4, Internet Archive, via www.archive.org.
  • Oil furnace, via http://activerain.com/image_store/uploads/1/0/2/6/5/ar125122617956201.jpg.
  • Globe and Mail, May 14, 1887.
  • Natural Resources Canada, via http://www.nrcan-rncan.gc.ca/residential/personal/gas-propane-furnaces.
  • Carrier furnace, source not found
  • Grimsby furnace, HHCC Collection.
  • Red Hot Huron furnace, Western Foundry, Eaton’s ad, Toronto Daily Star, February 3, 1908.

The early 1900s gravity warm air furnace

  • Scanned Image Table, No.S11.
  • Parlour Heater: The Ideal Fitter: 21st Edition, p.70, 1925. Scanned Image [Table HD007O], No. S46.
  • Schematic of Gravity Warm Air Furnace: Norris, Warm Air Heating and Winter Air Conditioning: Second Edition, McGraw Hill, pg.6, 1950. Scanned Image [Table HD007O], No.S43.
  • Steel Heat Exchanger: Howard Advertisement, 1940. Scanned Image [Table HD007O], No.S7.
  • Schematic of Forced Warm Air Furnace: Norris, Warm Air Heating and Winter Air Conditioning: Second Edition, McGraw Hill, pg.7, 1950. Scanned Image [Table HD007O], No.S12.
  • Scanned Image [Table HD007O], No.S44.

An automatic furnace milestone: The birth of the “Winter Air Conditioner”

  • Scanned brochure (detail), 004_0 (furnace), Howard Furnace and Foundries Ltd., Toronto, 1940, T.H. Oliver Collection.
  • Ibid., 004_1 (burner), Howard Furnace and Foundries Ltd., Toronto, 1940, T.H. Oliver Collection.
  • Ibid., (detail), 004_2 (coal feeder), Howard Furnace and Foundries Ltd., Toronto, 1940, T.H. Oliver Collection.
  • Ibid., 004_134 (filter, fan, humidifier), Howard Furnace and Foundries Ltd., Toronto, 1940, T.H. Oliver Collection.
  • Ibid., 004_25 (blower, motor), Howard Furnace and Foundries Ltd., Toronto, 1940, T.H. Oliver Collection.
  • Scanned flyer, 004_5, Howard Furnace and Foundries Ltd., Toronto, 1958, T.H. Oliver Collection.
  • Ibid., (detail), 004_6 (hi-boy furnace), Howard Furnace and Foundries Ltd., Toronto, 1958, T.H. Oliver Collection.
  • Scanned brochure (detail), 004_7 (rec room), Howard Furnace and Foundries Ltd., Toronto, 1940, T.H. Oliver Collection.

Initial development of the first condensing gas furnaces in Canada

  • Public domain, via Wikipedia Commons.
  • 2003 Survey of Household Energy Use (SHEU) – Summary Report, Office of Energy Efficiency, Natural Resources Canada, via http://oee.nrcan.gc.ca/publications/statistics/sheu-summary/residential.cfm?attr=4.

The trials of developing a condensing oil-fired furnace

  • “Dornback Furnace Division”, n.d., http://www.dornbackfurnace.com.
  • Ibid.