What is zone heating and how can it save on central heating costs?
Forced air central heating systems distribute heated air from a central furnace unit through ducts to various points in the home. The furnace burners cycle on and off as often as 3-4 times per hour depending on the thermostat's setting and sensitivity. Typical gas furnace inputs range from 80,000 to 120,000 BTU/hr and are sized to heat the home in the very coldest weather.
During average heating weather, furnace "on cycle" times may be relatively short with the burners shutting down before peak efficiency is even reached. This results in reduced efficiencies through "cycling losses" (like a car's mileage in stop and go traffic). Also, room comfort levels fluctuate along with furnace heat cycles, sometimes warm one minute and cool the next. With central furnace systems, it's often necessary to overheat portions of the home just to get comfortable in the area where you actually are.
By contrast, an efficient zone heater puts warmth directly into the space you wish to heat with virtually no cycling losses. Both electric and gas stoves, fireplaces and inserts utilize special lightweight steel and ceramic components to heat up quickly and reach efficiency in minutes. Installed in one or more of your main living zones, you can enjoy increased comfort while reducing furnace usage in colder weather, or eliminating it during warmer Spring and Fall weather.
What is a BTU?
A BTU or British Thermal Unit is the amount of heat required to raise 1 pound of water 1 degree fahrenheit. All gas appliances are rated in BTU's/hr Input which is an approximation of the amount of gas consumed on full fire in one hour as expressed in terms of the heat potential of the gas. Depending on the design and efficiency of the appliance, a certain proportion of the heat generated from burning ends up as useful heat in the room (Heat Output) while some portion is lost to vents and chimneys (Flue Loss). We encourage the use of efficient appliances in a 70% + range, both for the benefits they provide to the homeowner and as a means of conserving fuel. Efficiency is determined at full fire, without optional blowers, and after the heater is up to operating temperatures.
How many BTUs will I need?
The amount of heat you require will depend on a number of factors such as room size, insulation levels, amount and type of windows, climate and the type and use of other heating systems in the home. It will also vary from hour to hour, day to day and season to season because of these same factors. To give you a general guideline, studies average winter home heat requirement was between 10,000 and 20,000 BTU/hr. Specifically, a 1300 square foot house in Vermont with average insulation required 14,000 BTU/hr in January and February.
What is the Comfort Zone and how does this relate to BTU's?
The Comfort Zone is that area in your home that can attain an even comfort level using a steady burning efficient heat source like a stove or fireplace. Depending on your house layout and fireplace location, the Comfort Zone may be one room or a complete level or zone. In Fall or Spring, a high efficiency gas zone heater may easily provide comfort for the entire home. The amount of BTU's of heat necessary to maintain this Comfort Zone is generally in the range of 5,000 to 15,000 BTU/hr. This relatively small amount of heat can be very effective, especially when it is constant and not operating in an "on/off" cycle like a furnace. In fact, too large a heat output will overheat your room; the "Bigger is Better" mentality just doesn't make sense. With a truly efficient zone heater, this is simply not the case.
Why is adjustable heat output so important?
Most hearth appliances are designed with variable heat controls that you can turn down to a very low setting when needed. A high BTU fireplace with limited turn down is just another furnace and will not provide a Comfort Zone. This is another reason we're particularly fond of the small hearth appliances in which we specialize; they do a great job while burning fuel effiiciently.