Supplemental home heating for the cost of running a light bulb
The Attic Heat Harvester System is an extraordinarily efficient supplementary heating system that automatically provides very cheap heat at periods during the year when your home needs heat and hot attic air is available. The heat produced replaces far more expensive heat produced by all other home heating systems reducing your heating costs and the associated CO2 emissions.
The attic heat harvester payback time i.e. the time it takes for the initial cost of the attic heat harvester system to be recouped in energy savings, is far shorter than for all other heating systems but is difficult to accurately predict.
The major factors that determine the attic heat harvester payback time are:
a) Your heating costs
Installing an Attic Heat Harvester system in a UK home as a supplementary heating system will typically save you from 5 to 20% of your annual heating costs, the larger your heating costs the shorter the heating system payback time.
Heating costs vary greatly. Harvesting attic heat can save you considerably more if you're supplementing an electric, LPG or oil fuelled system than if your heating system is fuelled by gas. If your heating system is old your saving will be even greater and the payback time even shorter.
b) Your home's location
The amount of heat available to harvest is dependant on your home's location, especially it's latitude as this determines the amount of solar energy that heats the attic roof.
c) Your home's attic size, sunny roof area, roof pitch and construction
Large attics with dark surfaced sun facing roof areas absorb the most solar energy.
d) The length of the insulated duct
The hot air flow rate and hence the system efficiency reduces as duct length increases due to added air turbulence, air flow will be usually be greater the fewer the number of floors the duct passes through.
e) How poorly insulated your home is
A poorly insulated home needs more heating energy so harvesting attic heat in poorly insulated homes will reduce heating system payback time, however we strongly advise that your first priority be to insulate your home.
f) Your system installation costs
Attic heat harvester supplementary heating systems are generally easier and less expensive to fit to single floor homes than to multi-floor homes and in 'new-build' homes than to retrofitting to existing homes.