Technology has changed everything drastically over the last 150 years, including the way we heat our homes. The heating systems of today have come a long way from the days of wood-burning stoves, offering a variety of ways to heat modern homes that are both more economic and more ‘green’.
Prior to 1885, most American homes used wood burning fire places, or metal lined devices called Franklin Stoves (invented by Benjamin Franklin in 1742). This was the prevailing technology of the time, and wood was plentiful.
Toward the end of the 19th century, metal lined stoves gave way to cast iron radiators. This type of heating system ushered in the era of central heating for American homes. A coal-fired boiler in the basement would send hot water or steam up through pipes to radiators paced in each room.
In the same period, Dave Lennox invented the first riveted-steel coal furnace in 1885. With no electricity, these furnaces utilized the natural conversion of warm air rising, transporting heat through ducts from a basement to the rooms upstairs.
Since there was no electricity to move the air around, these furnaces were able to transport the heat through natural conversion or warm heated air rising from the basement furnaces to the rooms upstairs.
In 1935 electricity entered the picture with the development of the first forced air furnace. This system utilized the power of an electric fan to distribute coal-fired heat through ductwork. Shortly after 1935, gas- and oil-fired versions of forced air furnaces became the prevailing technology.
Today approximately 71% of US homes heat using a central warm-air furnace. Nearly 14% of those use a heat pump, which supplies both heated and cooled air.
For most, heat pumps provide an energy-efficient alternative to a traditional furnace and air conditioning system. They still use electricity to move air, but because they move warm or cool rather than generate it, they operate at little as 25% of conventional heating and cooling equipment.
There are several different types of heat pumps:
Air-source heat pump – Uses air to transfer heat in the air out for cooler temperatures, or inside for warmer temperatures.
Ductless mini-split heat pump – Provides heat pump efficiency without any ductwork. A small outdoor compressor/condenser connected by a conduit to as many as four indoor air-handling units – each with its own thermostat. Oversized or poorly located units can end up wasting energy and costing more. Check which of your local HVAC contractors have experience installing ductless mini-split heat pumps.
Geothermal heat pump – Uses the constant temperature of the earth instead of air as the exchange medium – transferring heat between your house and the ground or a close water source. These are significantly more expensive to install, but they are significantly lower operating costs, do not depend on outside temperatures, and require little to no maintenance.
Absorption heat pump – Works by way of an ammonia-water absorption cycle, absorbing heat from the interior of a room for cooling, and/or releasing heat into the interior for heating. They’re powered by natural gas, propane, solar energy, or geothermal-heated water instead of electricity, and most often used in commercial or industrial buildings.