Heating & Cooling Your Home

Typical types of heating systems

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• 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.

• 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 heating system.

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• 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.

Ground source heat pumps

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• The right choice for you?

  

  Many Vermonters are wondering if a ground source heat pump (GSHP) would lower their energy costs. A GSHP system requires a large initial investment, so it makes good economic sense to determine whether this technology will be cost-effective for your specific needs. This page will help you identify important points to consider as you evaluate your options.

• What is a ground source heat pump?

  A GSHP system uses electricity to pump heat to and from the ground to heat and cool a building. The ground acts as either a heat source for heating or a heat sink for cooling. The system includes an electric water pump, to pump the water used to transfer heat to and from the ground, and a type of compressor called a heat pump. To provide heating, the heat pump extracts and concentrates heat from the incoming water and transfers it to a building's heat-distribution system (forced air or water) and/or water-heating system. To provide cooling, the heat pump transfers heat from a building's air to water that is then pumped back underground.

• There are multiple GSHP options in Vermont.

  Most installations use open-loop systems, in which groundwater is pumped from a drilled well through a heat pump, which transfers heat into the building, and then most of the water is pumped back to the well. Closed-loop systems circulate a heat-transfer fluid through coils of buried tubing to move heat either to or from the ground.

  Choosing a system appropriate for the physical characteristics of your property and for your budget requires the design expertise of a GSHP contractor, along with the advice of an unbiased energy professional. For commercial buildings, this energy professional would be a mechanical engineer who is familiar with GSHP technology and alternatives. For residential buildings, speak with a certified Home Performance with ENERGY STAR^® contractor.

  

• Vermont commercial buildings

  Typically, GSHP systems installed in Vermont commercial buildings are designed to provide both heating and cooling. The cost effectiveness of a GSHP system is likely to be greater when it's installed at the time of building construction, rather than as a replacement system, and when the building has large heating and air-conditioning needs. However, it may also be cost effective, in some circumstances, to replace existing commercial heating and cooling systems with GSHP systems. For more information about using GSHP systems in commercial buildings, visit the commercial HVAC page.

• Vermont Homes

  Most GSHP systems for homes in Vermont are designed to supply space heat and, less often, to provide air- conditioning and/or supplement water heating. For homes with smaller heating needs that also require little or no air conditioning, the cost effectiveness of a GSHP is more limited. Also, it's more cost- effective to place a GSHP system in a new home than in an existing home because installation costs are lower at the time of new construction.

• Efficiency First

  Regardless of the kind of heating/cooling system you use, keep in mind that the first steps toward reducing heating and cooling costs are to minimize air leakage and to optimize the insulation levels of a building. This is particularly important with GSHP systems. That's because the cost of buying and installing a larger-capacity GSHP system is typically far greater than the cost of reducing a building's heating and cooling needs through energy efficiency.

  For residential customers, you can find a Home Performance with ENERGY STAR contractor to guide you through a GSHP project. 

  For commercial customers, you can find an HVAC professional serving commercial customers to help guide you through a GSHP project. 

• How efficient is it?

  Although GSHP equipment may be rated as efficient, the actual overall operating efficiency of a system will be lower than the rated equipment efficiency because of the amount of electricity required by the system's pumps. System efficiency may be further reduced by flaws in design and/or installation. The extent of efficiency losses varies from one installation to another, but losses can be significant. The efficiency of GSHP equipment, in heating mode, is indicated by its coefficient of performance (COP), which is the amount of heat provided per unit of energy used. The efficiency of the equipment in cooling mode is indicated by the Energy Efficiency Ratio (EER), which is the amount of heat removed per unit of energy consumed. ENERGY STAR qualified heating and cooling equipment installed as part of a GSHP system must meet or exceed the efficiency standards outlined in the table below:

  GSHP System Type	ENERGY STAR Minimum Equipment Efficiency
  	Heating (COP)	Cooling (EER)
  Open-Loop System	3.6	16.2
  Closed-Loop System	3.3	14.1

• Potential benefits

  • A well-designed and correctly installed GSHP system can be an efficient way to use electricity to heat and cool some buildings, such as larger buildings with substantial air-conditioning loads.
  • When used for heating, GSHP systems can emit up to 50% less carbon dioxide than is emitted by other fossil-fuel heating systems. Even greater emission reductions can be achieved when the electricity to power GSHP equipment comes from renewable sources, such as solar or wind.
  • The potential for a GSHP system to reduce heating and cooling costs from those of conventional heating and cooling systems generally increases as energy prices increase.

• Potential drawbacks

  • GSHP systems are significantly more expensive to purchase and install than conventional heating and cooling systems. The cost to purchase and install a residential GSHP system can range from $10,000 to $30,000 more than the cost of a conventional system. It is difficult to estimate a comparable range of costs for commercial applications because each situation is site-specific.
  • GSHP systems that distribute heat through baseboard convectors or radiators generally will not perform well. This is because GSHP systems produce relatively low-temperature hot water. However, GSHP systems typically work well with low- temperature heat-distribution systems like radiant floor heating systems and forced air systems.
  • Some existing water wells don't have enough supply to meet the needs of an open-loop GSHP system. In these situations, a new well, pumping equipment, and possibly water treatment equipment may need to be purchased. Drilling through difficult soils and rock can increase initial investment costs.
  • Some residential GSHP systems deliver most but not all of a home's heating needs. Homes with such systems require supplemental heat during the coldest periods of winter. All supplemental heating equipment and operating costs should be considered when determining whether a GSHP system will be a cost-effective investment. An economic analysis worksheet is available to assist you in determining whether a GSHP system could be cost-effective in your building.

• Exercise care

  The GSHP industry is relatively new to Vermont. Currently, purchase and installation costs vary considerably from supplier to supplier and installer to installer. Also, only anecdotal data exists regarding the performance and operating costs of systems installed in Vermont. This makes it difficult to accurately compare vendors' cost projections with Vermonters' actual experiences. Whether in a commercial or residential application, it's advisable to exercise care in choosing equipment vendors and installation contractors. Efficiency Vermont recommends obtaining an independent assessment of savings estimates, which can be provided by an energy professional who is familiar with GSHP technology and alternatives. Before investing in a GSHP system, it's a good idea to balance purchase, installation, maintenance, and fuel costs against potential energy savings to determine whether you'll see a return on your investment. An economic analysis worksheet is available to assist you in determining whether a GSHP system could be cost-effective in your building.

• Steps to take to see if a GSHP system is right for you.

  1. The most important step is to work with an independent and objective energy professional. These experts can assess the efficiency of your building and calculate its heating and cooling needs. They also can inform you about cost-effective improvements you can make to reduce heating and cooling needs before investing in a new GSHP system.

     
     

     For residential customers, you can find a Home Performance with ENERGY STAR contractor to guide you through a GSHP project. 

     For commercial customers, you can find an HVAC professional serving commercial customers to help guide you through a GSHP project. 

     
     

     Please note: Efficiency Vermont does not endorse any particular partner in promoting this service. Efficiency Vermont neither expressly nor implicitly warrants the performance of any partner. Contact your contractor or supplier for details regarding equipment warranties.

  2. Contact a firm specializing in GSHP equipment and its installation. Ask for an estimated cost to purchase, install, and maintain the system.

     For a list of firms, please visit:

     • International Ground Source Heat Pump Association Business Directory
     • Renewable Energy Vermont Business Listing

     Please note: Efficiency Vermont does not endorse any particular partner in promoting this service. Efficiency Vermont neither expressly nor implicitly warrants the performance of any partner. Contact your contractor or supplier for details regarding equipment warranties.

  3. Work with your energy professional to compare your current heating and cooling energy costs with those incurred with a GSHP. For a commercial building, also ask for a life-cycle cost analysis.

     To help compare costs, a fuel-cost calculator and a GSHP economic analysis worksheet are available:

     • Fuel Calculator
     • GSHP Economic Analysis Worksheet

     To find available tax credits & incentives please visit:

     • EnergyStar.gov
     • DSIREUSA.org
  4. Contact Efficiency Vermont for information about how to evaluate a GSHP system for your application. We're here to help you find answers to your questions, so that you can decide whether a ground source heat pump is a cost-effective system for your needs. Call, toll-free, 888-921-5990.