Heating Systems

Heating accounts for about half of a Vermont home's energy needs. After your house and car, a central heating system is likely to be your largest purchase. It should last at least 20 years, so it's worthwhile to consider your heating options carefully. Heating systems can use a variety of energy sources: oil, natural gas, propane, electricity, kerosene, wood, coal or the sun. If you heat your home primarily with electric baseboard heat or portable or permanent electrical heat sources, please call Efficiency Vermont. We can help reduce your electricity costs.

TYPICAL TYPES OF HEATING SYSTEMS:

FURNACES

Furnaces distribute heated air through a system of supply and return ducts. Heated air enters rooms through supply ducts and is brought back to the furnace for reheating through return ducts. Some high-efficiency furnaces also use high-efficiency fan motors sometimes called Electronically Commutated Motors (ECM) or brushless DC motors. These motors use about half the power of a standard furnace fan motor and can thus reduce your winter electric bills. And if you have a central air conditioner, you can save on summer electric bills.

Furnace ductwork needs to be balanced so that rooms with supply registers do not become pressurized and rooms with returns do not become depressurized. Both of these situations can increase air leakage between indoors and out, which can contribute to poor indoor air quality. Twenty percent or more of the heat your furnace produces can be lost through leaky ductwork. To avoid this problem, use smooth-wall metal ducts sealed with foil tape or mastic sealant and then insulated. Avoid installing ductwork in unconditioned spaces such as attics, knee walls and crawl spaces. Clean and replace filters at least once per year or as often as necessary to ensure clear pathways for air.

BOILERS

Steam Boilers

Steam boilers heat water until it becomes a vapor and quickly distribute the steam through pipes to radiators. The radiators distribute heat to each room, and the condensed water then returns to the boiler (either in the same pipe or through separate piping) for reheating into steam.

Hydronic Boilers

Hydronic boilers (also called hot water systems) use pumps and valves to move heated water to radiators, baseboard convectors, or radiant floor systems. Different areas of the house can be "zoned" so that the temperature can be adjusted separately in each zone. Insulate pipes and avoid installing hot water distribution in unconditioned spaces such as attics, knee walls and crawl spaces. Radiant floor heat distribution systems should be insulated on the underside of the floor.

SPACE HEATERS

Space heaters are essentially "spot" heaters that heat a single room or even the whole house if it's a small or very efficient house with an open floor plan. A wide variety of space heaters exist, using different kinds of fuel. Some have supplemental fans to help distribute heat. Depending on the characteristics of the space intended to be heated, more than one unit may be required. If you have a constant need for supplemental space heaters, you may have insufficient insulation and/or excessive air leakage that needs to be repaired. If you need to use electric space heaters, take proper safety precautions. Space heaters should be positioned away from any flammable materials and should not be left unattended.

Unless operated exclusively by electricity, space heaters should always be vented to the outside. The combustion process creates harmful byproducts (including carbon monoxide) in addition to large amounts of water vapor, and it is important that these pollutants be removed from your home. If you choose to use an unvented or "vent-free" heater in your home, be aware that you must also have an oxygen depletion sensor (often integral with the unvented heater) and a carbon monoxide detector. Unvented heaters must be used in well-ventilated areas.

WOODSTOVES

Woodstove efficiencies can range from under 50% to almost 80%, depending on their construction and on how they are used. You can increase the efficiency of your woodstove by keeping the stove temperature high enough to completely burn the wood and combustion gases. Consult the manufacturer or your supplier for recommended temperatures. You can purchase a temperature gauge designed specifically for woodstoves that shows you when your stove has reached optimal temperatures.

FIREPLACES

Wood-burning fireplaces are great for aesthetics and ambiance, but they typically lose more heat than they generate. Fireplaces also waste large amounts of the heat generated by your central heating system by drawing in cold outdoor air through any leakage points in the house. Traditional wood fireplaces are, therefore, best used when the central heating system is not needed. Sealed-combustion gas fireplaces can be over 90% efficient and are thus a far better choice as a useful heat source.

Wood-burning fireplaces should have well-fitted glass doors and a source of outside air for the firebox.

Woodstoves and fireplaces should not be operated for extended periods with just a smoldering fire because those produce substantial amounts of carbon monoxide, particulates and creosote.

Well-seasoned wood burns cleaner and also optimizes the amount of useful heat energy gained. Be sure to close the damper tightly when the fireplace/woodstove is not in use. A specially designed chimney balloon or rigid insulation can help reduce heat loss up the chimney when it's not in use. To prevent chimney fires and blockage, keep chimney flues clear of creosote and be sure that the chimney is in sound condition. Have a professional chimney technician inspect and clean all chimneys at least once a year.

ELECTRIC HEAT

Electricity is the most expensive energy source in Vermont, even as gas and oil prices rise. Not only does it cost you a lot of money to heat with electricity, but the amount of energy used is far more significant than many people think. If electric heat is utilized during the coldest periods of winter, Vermont's energy demands will increase, ultimately leading to higher electricity rates. If you use electricity to heat your home, please call Efficiency Vermont. We can help reduce your electricity costs.

TAKING CONTROL OF YOUR SYSTEM:

Whatever type of heating system you have, you can optimize its efficiency through the way that you operate it. Here are three strategies to keep in mind:

Thermostats

By turning the temperature down 10º while you are asleep and while the household is away for the day (16 hours per 24hour period) you can reduce your annual heating costs by as much as 15%. Use a programmable thermostat to automatically have your house warm for you when you get up and when you come home at the end of the day. The energy used to bring the house back up to a comfortable temperature does not exceed the energy you save while the thermostat setting is lower.

For any thermostat to function properly, it must be located in the space you want to heat. And keep in mind that you will not heat the room faster if you turn the heat up higher than you want the temperature to be.

Some thermostats rely on a mercury switch that needs to be level to be accurate. For this reason as well as because of environmental concerns, non-mercury models are recommended. If you replace a thermostat that contains mercury, dispose of it properly at your local solid waste district drop off point. Visit www.mercvt.org for more information, or call the Vermont Department of Environmental Conservation at 802.241.3455.

Zones

Having multiple heating zones allows you to keep the temperature low in rooms that are infrequently used. If you have a forced-air heating system, you save energy by closing registers and doors in unused rooms. However, this can unbalance your ducted distribution system which can affect the efficiency of the system and can lead to health and safety issues. Please contact your heating contractor or Efficiency Vermont with questions about zoning your forced-air heating system. With a hot water system, it's much simpler: Turn down the thermostat for the zones you don't wish to heat.

Outdoor Reset

With hot water systems, you can install controls that optimize the efficiency of your system. The outdoor reset control senses the outdoor temperature and adjusts the water temperature in your boiler accordingly. In this way, you maintain a comfortable house while heating the water only to the temperature that you need.

BUYING NEW HEATING EQUIPMENT:

Thinking of Switching to Alternative Fuels?

If the heating system in your house is older than 20 years, it's near the end of its useful life. It's a good idea to replace it before it fails. New systems are far more efficient than older models, so they will keep you comfortable for less money. The indicator of efficiency is the AFUE (Annual Fuel Utilization Efficiency) rating. The higher the AFUE rating, the lower your heating costs. Look for equipment with a minimum efficiency rating shown in the table below. You can find the AFUE on the yellow Energy Guide tag attached to the equipment. Note that this rating applies only to your furnace or boiler, not to the parts of your system that distribute heat. Both of the components need to be appropriately sized and installed, or they can substantially reduce total system efficiency.

Exception: Oil furnaces or boilers rated higher than 87% AFUE are not currently recommended due to their higher maintenance requirements. When buying furnace and boiler systems, look for the ENERGY STAR® label to ensure that you are getting high efficiency. Woodstoves, gas space heaters and fireplaces are not available with the ENERGY STAR label.

A key to optimizing your system's efficiency is to make sure that it's the right size for your home. An oversized system not only will be more expensive to purchase, but also will be more expensive to operate. This is because it will cycle on for shorter periods of time than an appropriately sized system will. This results in a fuel-inefficient system much like a car getting worse mileage on short city drives than on long highway drives. Ask your heating contractor to perform a heat loss calculation of your home in order to properly size your heating system.

Woodstoves

To find an efficient woodstove, look for a model that heats secondary combustion air - which ensures more complete combustion of the flue gases - and with ceramic glass which radiates heat well. To find a woodstove that has been certified to meet U.S. Environmental Protection Agency (EPA) standards look for a label indicating the model's efficiency and particulate emissions.

Make sure your woodstove is properly sized for the room where it is to be located. An oversized woodstove will operate on low burn more frequently, which is an inefficient way to burn wood. It also results in creosote buildup, which is a cause of chimney fires. A good retailer of woodstoves should be able to help you choose the proper size for your needs. In a well-insulated house, you can increase your stove's efficiency and improve its drafting ability by bringing combustion air directly from the outdoors. Ask for a manufacturer's combustion air kit.

Pellet Stoves

Wood pellet stoves burn more efficiently than their cord wood counterparts. Pellet appliances include efficiency boosting features such as an electric igniter, fan-induced air supply and a pellet feeder that work together, often by thermostatic control, to adjust the fuel-to-air ratio. These features allow the heat output to vary, resulting in a cleaner, more efficient wood burning process. Most pellet stoves cannot provide heat during an electricity outage, but battery backups are available for many types of pellet stoves.

Click Here for more on Wood and Pellet Stoves.

Fireplaces

An open-hearth masonry fireplace is not an efficient heat source. In fact, it can increase your energy costs by drawing your home's heated air up the chimney. However, there are a number of things you can do to increase the efficiency of your fireplace. Look for these features:

Sealed-combustion that draws outside air to the firebox.
Ceramic glass doors that prevent house air from being lost up the chimney.
Heated secondary combustion air, to burn wood most efficiently. You also can turn your existing fireplace into an efficient heating appliance by installing a sealed fireplace insert. If you choose not to include any of the above features in your open fireplace, you can reduce the loss of house heat up the chimney by using the fireplace when your central heating system is turned off

Gas "Wood" Stoves

Gas-burning stoves with glass doors and artificial logs are primarily decorative. However, a few manufacturers offer gas stoves that provide heat efficiently and have a high enough heat output for general heating. Some manufacturers list heating efficiency. However, because no standardized testing exists for gas-fired stoves, it is difficult to compare efficiency claims of different brands. The use of "vent-free" gas heaters and fireplaces is discouraged, because they can increase humidity in homes to levels where condensation on windows and other cool surfaces can increase.

Gas & Kerosene Space Heaters

Permanently mounted, gas or kerosene space heaters that are vented to the outdoors can be a good heating option for modestly sized, well-insulated, air-sealed homes. These heaters can also be useful when you need to temporarily warm a room that is otherwise unused. The most energy-efficient models have ducted outside combustion air and a programmable thermostat that you can set to control the room temperature on a given schedule. Many space heaters have an Annual Fuel Utilization Efficiency (AFUE) rating, established by the U.S. Department of Energy, that allows you to compare efficiency across brands. Look for a gas space heater with an AFUE of 80% or higher, or a kerosene space heater with an AFUE of 85% and higher. For safety reasons, an unvented portable gas or kerosene space heaters should never be used indoors.

COMBUSTION SYSTEMS SAFETY:

Fossil-fuel-burning and wood burning appliances, heating systems and water heaters create potentially lethal combustion gases. Ideally, these gases leave the house through a chimney or exhaust duct. However, conditions can exist under which combustion gases are drawn back into the house. This is called "backdrafting." This section will explain how the draft process works and how you can lower the risk of backdrafting and other hazardous conditions.

The Draft Process & Backdrafting

Gases leave the house through a process called "atmospheric draft." Atmospheric draft occurs when the high temperature of the gas causes it to initiate and maintain an upward flow, or draft, out of the building via the chimney flue pipe. However, the draft process can be overcome and reversed by negative pressures in the house created by exhaust fans, clothes dryers and combustion appliances. This causes the flue gases to enter the living space by spilling out the flue. Soot and debris under the draft hood is a sign that this has been occurring.

To reduce the potential for backdrafting:

All systems - Ideally, all systems that burn wood or fossil fuel should be sealed combustion units, which provide air directly from the outside to combustion equipment. All new homes built after December 31, 2004, are required by the Residential Energy Code to have outdoor combustion air delivered to all combustion appliances, including woodstoves and fireplaces. Another option is a power-vented unit, which uses a fan to force exhaust out of the house.
Woodstoves and fireplaces - See that woodstoves and fireplaces have tight-sealing doors and no chimney leakage to the inside.
Unvented Heaters - If you choose to use an unvented or vent-free propane or natural gas heater in your home, be aware that you must also have an oxygen depletion sensor (often included in the unvented heater). Unvented heaters must be used in well-ventilated areas in conjunction with carbon monoxide detectors. Also be aware that these heaters introduce substantial amounts of moisture into your home, potentially leading to moisture-related problems.

Other Important Safety Considerations:

To reduce the chance of fire, always maintain recommended clearances (distances from walls, floors and other combustible materials to the stove or fireplace). You can find out about required clearances from the manufacturer, the installer, your local code inspector or the fire marshal.

Never store flammable liquids (such as paint, gasoline, etc.) near combustion equipment. Fumes can be pulled into the air intake or flue pipe, causing corrosion, and a spill can be quickly ignited by the flames.