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[quote=Anonymous][quote=Anonymous][quote]I realize I’m only a stupid mechanical and electrical engineer who didn’t get a liberal arts degree from an Ivy, but perhaps one of you smart MBA’s or PhD’s can explain the whole “200% efficiency” thing to me?[/quote]

A heat pump is moving heat from outdoors to indoors, rather than creating heat by burning fossil fuel. If we put one unit of energy into a heat pump to power it, but it provides us with two units of energy in the form of heat, then its efficiency is 200%.

Even on a cold day, there is plenty of heat in the atmosphere that can be "harvested" by a heat pump and moved indoors. At the molecular level, heat is the movement of molecules -- and air molecules are always moving, even on a frigid winter day.

In contrast, a gas furnace burns fuel to create heat. The max possible efficiency is 100%, assuming we have a perfect gas furnace in which their is no loss of energy. With a perfect furnace, one unit of energy (stored in the gas) is translated into one unit of heat output. So the efficiency is 100%.

Modern heat pumps can achieve efficiencies of over 300%, versus a gas furnace that has, as a theoretical limit, an efficiency of 100%.

Its true that heat pumps are usually powered by electrical grids that depend heavily on fossil fuels, and it is also true that many power plants that use fossil fuel to generate electricity are wasteful and inefficient. So one has to consider the net effect -- the waste at the power plant versus the high efficiency of the heat pump. If a power plant wastes 30% of the potential energy stored in fossil fuel, but a heat pump is 300% efficient, then one still comes out way ahead using a heat pump -- that is, using a heat pump is, overall, a more efficient option for heating our homes.

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DP,  however natural gas is much cheaper than electricity so you don't really save money by switching and are probably paying more.[/quote]

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