The Heat pump “battle” carries on… Air Source versus Ground Source

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Variable speed compressor technology is not restricted to geothermal heat pumps. It had first found its way into what are often considered ground source’s poor cousins: air source heat pumps (ASHP).

Both types of heat pumps use a refrigeration cycle to draw heat from the outside in winter to heat a building, and pull heat from the inside to cool it in summer. GHPs use loops of buried tubing to exchange heat with the ground, while ASHPs use an above-ground fan and heat exchanger assembly similar to the evaporator on a traditional whole house air conditioner.

hp snowBefore the advent of variable speed compressor technology, air source heat pumps were only suitable in mild climates because heating performance fell off rapidly at temperatures below 10°C, while the near constant temperature of the earth allowed GHPs to operate efficiently in any climate. Now, the most efficient ASHP models only begin to lose significant heating efficiency at -15°C, a change which has made them more practical in most northern climates.

With variable speed technology, these ASHP units are now suitable for heating climates where the temperature occasionally falls below -18°C, although they always require some form of back up heat.



While variable speed air source heat pumps can be competitive with geothermal heat pumps in retrofit situations and smaller, better insulated buildings and less extreme climates, GHPs remain by far the most efficient way to heat and cool a building in northern climates.

If super-insulated, small buildings ever become the standard way to build a home, geothermal heat pump manufacturers may have something to fear from air source heat pumps. Fortunately for GHP manufacturers, but unfortunately for the rest of us, that day is still a long way off.

Coming soon…

WaterFurnace water-to-water heat pumps with OptiHeat vapor injection technology

This patented technology incorporates an additional heat exchanger that diverts excess heat and re-injects it into the system. This creates higher exiting water temperatures and optimum compressor operating conditions. Using standard R-410A refrigerant, the new 5 Series w-t-w will provide hot water up to 150°F and can utilized for high temperature application like baseboard radiant heat, pool/spa heating, radiant floor, snowmelt, aquaculture and process water installations.

Vapor-inj   VI-Compressor

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