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THE INSIDE SCOOP
GREEN BUILDER RECOMMENDS
The most effective steps a homeowner can take to keep a forced air heating system running efficiently are to seal and insulate the ducts, and clean the furnace filter. Heat can be lost from ducts running through unheated attics, basements, or garages. By using metal-backed tape to seal the seams between duct sections, then wrapping the ducts with fiberglass batt insulation, you can raise system efficiency by as much as 20%. To keep the system running smoothly, we also recommend cleaning or replacing the furnace air filter every three months.


 


AIR-SOURCE HEAT PUMP


VIRTUES
> Can provide heating and cooling
> No need for a chimney or exhaust flue
> More fuel-efficient than a fossil fuel furnace or boiler


CAVEATS
> Not practical in very cold climates
> Does not get air as hot as a furnace


GEOTHERMAL EARTH ENERGY
A geothermal heat pump (GHP) works on the same principle as an air-source heat pump. It can provide heating and cooling, but has a lower-temperature output in heating mode than a combustion appliance. What’s unique about a GHP is that it is a single unit that uses refrigerant-filled underground piping loops, installed horizontally or vertically, to exchange heat with the earth. Since underground temperatures tend to be stable year-round, these systems work well in warm and cold climates. A GHP is able to move three to five times more energy than it consumes, making it the most efficient heating system available. GHPs are available for use with forced air or hydronic distribution systems. While the hydronic models don’t get water as hot as a conventional boiler (122 F, compared to 150 F or more) their low temperature output is a perfect match for radiant floor heat.


 


GEOTHERMAL HEAT PUMP


VIRTUES
> Extremely energy efficient
> Good match for a radiant floor system


CAVEATS
> High installed cost
> Radiant loops can require a lot of land


 


A radiant floor consists of loops of hydronic tubing embedded in the structure of the floor. Warm water is pumped through the tubing which, rather than heating the surrounding air, radiates low-level infrared heat to the people and objects in the room. The tubing can be placed inside a concrete slab, or on top of a wood floor frame. In the latter, the installer typically routs channels for the tubing into the plywood subfloor. For retrofits, an easier way is to use a product like the Quik Trak system. It consists of pre-routed plywood strips that are laid over the existing subfloor, then covered with the finish flooring. www.uponor-usa.com


 


YORK AFFINITY MODULATING GAS FURNACE
The Affinity 9.C claims to be the highest rated gas furnace in the industry, with an AFUE of 98%. It includes a modulating burner that varies from 35% to 100% of maximum, in 1% increments, for exact temperature control. The variable speed blower motor operates quietly and efficiently while reducing electrical consumption. www.yorkupg.com


WEIL MCLAIN ULTRA SERIES 3 GAS BOILER
Ultra boilers feature AFUE efficiencies of 92%–93%. When used with a radiant floor system they can achieve system efficiencies up to 98%. The Ultra is also lighter than a conventional boiler—light enough, in fact, to be hung on a wall. Outdoor and indoor temperature sensors lets the boiler modulate its output for precise temperature control. www.weil-mclain.com


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GreenBuilder 11.2010

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