<h2><p>Heating and Cooling Systems</p></h2>		
		<p><a href="#anchor01">Efficiency Losses in a Heating System</a></p>
<p><a href="#anchor02">Duct Sealing</a></p>
<p><a href="#anchor03">Furnaces</a></p>
<p><a href="#anchor04">Heat Pumps</a></p>
<p><a href="#anchor05">Electric-Resistance Heat</a>
<p><a href="#anchor05">Hot-Water and Steam Boilers</a></p>
<p><a href="#anchor05">Upgrading or Replacing Heating Equipment</a></p>		
			<h1>Efficiency Losses in a Heating System</h1>		
		Not all the energy in the fuel you buy contributes to heating your house. Your heating system’s efficiency is the amount of useful heat you get as a percentage of purchased energy. Anything less than 100 percent represents waste, or lost efficiency. There are three kinds of heating system losses: combustion loss, cycling loss, and distribution loss. Combustion loss is simply the heat that goes up the chimney; it varies from about 30 percent to as little as 3 percent. That leaves a combustion efficiency between 70 percent and 97 percent; that is, the percentage of the fuel you buy that is converted to heat in the equipment. Combustion efficiency is mostly affected by equipment design; unless the burners are badly out of tune, it can’t be improved much unless you buy a new unit.
 Cycling losses occur when the heating equipment starts and stops. Each time the unit shuts off, some heat remains inside; some of that heat goes up the chimney. Cycling losses are affected by the equipment design, location, and controls; some efficiency improvements can be made if the controls are set poorly to begin with. Distribution losses occur when heat generated in the equipment gets out of the house before it reaches its destination. Distribution losses include duct air leaks and conductive losses through uninsulated ducts or pipes. Distribution losses can be significant: 5 percent to 30 percent, so in many homes a large improvement can be made.
			<p>Comfort and energy use</p>		
		Another fairly simple factor that affects heating-system performance is system balancing. Balancing refers to the temperature consistency from one room to the next. If one or more rooms are consistently too cold, people tend to set the thermostat high enough to be comfortable in those rooms. The rest of the house then overheats, using more energy. Balancing problems can be caused by thermal defects in the building, by problems in the distribution system, or by the thermostat location. Rooms that have air leaks, drafts, or missing insulation may lose heat faster than neighboring rooms, or they may just be uncomfortable. Thermal problems should be fixed before addressing the heating system. Once the building enclosure is properly treated, the distribution system can usually be adjusted for better balance.		
			<h1>Duct-Sealing</h1>		
		<p>Air leaks in a duct system can have an enormous effect on your house. Duct leaks rob a furnace, heat pump, or central air system of energy— sometimes close to half. Leaks can cause comfort problems, drive moisture flows, and sometimes even lead to dangerous back drafting of combustion equipment. Leaky basement ducts don’t usually waste much energy; sealing them is pretty easy, but there’s not much value to it. But ducts located in attics, garages, or vented crawlspaces can be a big energy problem. Sealing them can be the biggest opportunity for energy savings in many homes. Leaky ducts do more than let heat out. They also increase the air exchange in a house by 30 percent to 300 percent whenever the air handler is running. That is why furnaces have the reputation for drying out houses. Return leaks in a mechanical room or basement can backdraft a nearby water heater or even the furnace itself. Return leaks can also draw in radon gas, water vapor, subsoil pesticides, or airborne mold spores, distributing them throughout the house.</p><p>Supply air leaking into an attic or enclosed cathedral ceiling cavity can deliver moisture at an accelerated rate to cold roof sheathing, causing condensation. If the ducts also carry central air-conditioning, return leaks can bring in outdoor humidity in the summer, reducing cooling efficiency, and leaks can draw outside air into building cavities, where moisture can lead to mold inside the house. Duct leaks are even more important than shell air leaks: Each hole and crack is under pressure from the furnace fan and leaks the hot air from your furnace (or cold air from your air conditioner).</p>		
							<figure>
										<img src="/wp-content/uploads/2018/07/Heating_Pic1.png" title="Heating_Pic1" alt="Heating_Pic1" />											<figcaption>It’s important to peel back the insulation and vapor jacket to seal the duct connections. The black stains are from the air leaks.</figcaption>
										</figure>
		Return ducts can be a bigger challenge. Return systems are frequently patched together using a combination of plywood, sheet metal, joist or wall cavities, and a lot of wishful thinking. Many HVAC installers don’t pay much attention to returns, focusing mostly on supplies that get the air to where it’s supposed to go. But well-sealed returns are important for furnace efficiency, occupant health and safety, and building durability. Fortunately, it’s not typically necessary to seal ducts that are buried inside interior wall and floor cavities. However, you do want to ensure that those cavities don’t leak to outside spaces; if they do, seal those leaks at the thermal boundary to keep the ducts and the indoor air inside.		
			<p>Duct insulation</p>		
		<p>Ductwork that runs through unconditioned space should be insulated, if it is not already. Typically, supply ducts are insulated but often have weak spots at register boots and other major connections. Often, return ductwork is left uninsulated.</p><p>Ducts should be insulated with vinyl-faced fiberglass wrap; R-6 is the minimum allowed by current residential codes; R-8 is required for supply ducts in attics. If possible, attic ducts should have higher R-values. Think about it: In winter, attic temperatures are nearly as cold as outdoors; in summer (for air-conditioning ducts), they are often much hotter than outdoors. If the ducts are close to the attic floor, cover them completely with loose-fill insulation. If that is not possible, try to find R-10 or higher duct wrap. Of course, seal all the duct connections tightly before insulating.</p>		
			<h1>Furnaces</h1>		
		The furnace is by far the most common type of heating system in the country. In fact, it’s so common that many people use the word furnace to describe any type of heating equipment. Furnaces create heat by burning fuel, usually natural gas. Oil and liquefied petroleum (LP, or propane) gas are also used in areas where piped gas is unavailable. By contrast, heat pumps and electric furnaces use electricity to heat the air; they also use a duct system to deliver heat, but they are not furnaces and do not have a fuel supply, chimney, or vent pipe. Boilers burn gas or oil but create hot water or steam instead of warm air. Furnace efficiency can be improved by performing regular maintenance, improving airflow, adjusting control settings, and sealing leaky ductwork.		
										<img src="/wp-content/uploads/2018/07/Heating_Pic2.jpg" title="Heating_Pic2" alt="Heating_Pic2" />											
			<p>Regular maintenance</p>		
		<p>Regular furnace maintenance is important to keep things running well, just as with any machine, but tune-ups and filter replacements don’t really save energy. Be sure to change the filter once or twice a year; more frequently is not much benefit because filters actually work better once some dust has built up on them. If the filter never gets dirty, however, then you may have a duct leak that is causing a loss of efficiency. Keeping registers open and free of obstructions may help your comfort, but this also won’t affect your energy bills noticeably.</p><p> </p><p>If you have a gas furnace, you should have it cleaned and tuned every two to four years. An oil burner should be tuned every year. Don’t wait until cold weather hits—that’s when the service companies are busy. You may get a better price if you get the tune-up in the spring.</p>		
							<figure>
										<img src="/wp-content/uploads/2018/07/Heating_Pic3.png" title="Heating_Pic3" alt="Heating_Pic3" />											<figcaption>Air filters should be replaced occasionally for best furnace performance. This pleated filter is more effective than the standard cheap fiberglass filter, and it doesn’t cost much more.</figcaption>
										</figure>
			<p>Low airflow</p>		
		<p>Low airflow can also reduce furnace efficiency. It can be caused by clogged air-conditioning coils, low fan speed settings, loose fan drive belts, undersized ductwork, or duct obstructions. Sometimes airflow is low to one room or section of the house, causing discomfort. Diagnosing low airflow is complex, but once identified, the fixes are usually fairly easy and inexpensive. These improvements are probably better left to a professional, but it’s good to be informed, because many technicians don’t bother checking airflow. If a service person is unable to explain in sensible terms what is happening in your system, you may want to get an opinion from another technician.</p>		
			<p>Furnace Tune-Up</p>		
		A professional tune-up for a gas furnace includes cleaning the burner and heat exchanger, checking the adjustment of air and fuel flow, cleaning and checking the heat exchanger for leaks, and testing draft pressure and carbon monoxide levels. The air-handler fan should be cleaned and lubricated as needed, once every two or three tune-ups. In addition, internal controls may be checked and adjusted if necessary. Don’t expect any real energy savings from a gas furnace tune-up; every two to four years is often enough. Oil burners are more finicky than gas burners. Most oil furnaces benefit from annual professional service; fuel filters, burner nozzles, electrodes, combustion chamber, heat exchanger, and flue pipe all need regular cleaning and adjustment. Checking heat exchangers and testing combustion efficiency are also useful. Try to find a technician who is knowledgeable, methodical, and thorough. If you have an oil furnace, the service technician might also recommend installing a smaller oil nozzle. This can reduce the heat output of the furnace, better matching it to the house and increasing operating efficiency slightly.		
			<p>Furnace control settings</p>		
		<p>The furnace controls can also have an impact on efficiency. The blower control, located above the heat exchanger, turns on the blower when it senses heat from the burner. The fan-on temperature should be set so the blower comes on between 90°F and 105°F; if it’s set too high, the burner will fire for a long time before the fan comes on, letting excess heat go up the chimney. If it’s set too low, the circulating air may feel uncomfortably cool.</p><p> </p><p>The fan-off temperature must be slightly lower than the fan-on temperature: between 85°F and 100°F. The lower it is set, the longer the fan will run at the end of the cycle when the thermostat turns off the burners, moving residual heat from the heat exchanger to your house. If your fan-on and fan-off temperatures are fixed (rather than adjustable) and set too high, the control can be replaced. Note that the temperature markings on adjustable controls are often poorly calibrated. Verify the actual fan-on and fan-off temperatures with a thermometer in the supply plenum.</p>		
			<h1>Heat Pumps</h1>		
		Air-source heat pumps, popular in some parts of the country, are basically air conditioners that can work in reverse to deliver heat into the house in winter. Heat pumps provide heating and cooling in one machine, with one duct system and no combustion. Heat pumps are not subject to backdrafting, combustion air requirements, or some of the offcycle losses to which furnaces are prone. Because they use ducts to deliver warm air to the house, heat pump ducts in attics, garages, and crawlspaces must be sealed thoroughly and insulated well. Heat pumps are more prone to airflow problems than furnaces are, and improper refrigerant charging can have a negative impact on both heating and cooling efficiency. 		
			<p>Operating efficiency and resistance heating</p>		
		Heat pumps are rated using Heating System Performance Factor, or HSPF. An HSPF of 6.8 corresponds to an efficiency of 200 percent. Most new heat pumps vary from 7.3 to about 10 HSPF; the larger the number, the more efficient the unit. An HSPF of 10 is approximately equal to 290-percent efficient—for every kilowatt-hour (kWh) of electricity you buy, you get almost 3 kWh of heat delivered to your house. How can a heat pump generate more energy than it consumes? The difference is made up by heat energy absorbed from the outdoor air. That energy goes into the system; because it’s free, it’s not counted in the measurement of efficiency. Most heat pumps, by themselves, operate at reasonable efficiencies until outside air temperatures drop to about 35°F to 40°F. As the outdoor air gets colder, less heat is available, and the heat pump output drops off, even as the house needs more heat. So cold-weather performance is typically supplemented with electric-resistance backup heaters. This auxiliary heat costs about three times more per unit of heat than the compressor heating cycle. That may be fine in regions with long summers, mild winters, and relatively low electric rates, but it’s not in much of the North, where electricity is expensive and winters are cold. One fairly inexpensive way to reduce the use of electric-resistance heating is to install an outdoor cutout thermostat. For about $100 to $150 installed, this device locks out the supplemental electric heat when the outdoor air temperature is above 30°F or 35°F.		
			<p>Airflow</p>		
		Heat pumps are even more sensitive to airflow than furnaces are. Heat pumps need to move a larger volume of air, but installers who are used to working with furnaces sometimes skimp on duct sizing, leading to low-airflow problems. Unfortunately, checking the airflow of a heat pump is not as easy as checking that of a furnace. It can be done with special instruments or with a version of the temperature-rise method used with the electric-resistance backup heat. Don’t attempt to take these measurements unless you understand exactly what you are doing—if you aren’t sure, get a service technician to do it for you. For best efficiency, heat pump airflow should be 375 CFM to 425 CFM per ton of heating capacity. It should never be below 300 CFM per ton. One ton equals 12,000 Btu per hour, and equipment is typically rated in increments of 1⁄2 ton, such as “24” (×1,000 Btu, or 2 tons), “30” (21⁄2 tons), “36” (3 tons), etc.		
			<p>Refrigerant charge</p>		
		Older heat pumps are also finicky about refrigerant charge. Many heat pumps, even when serviced regularly, are either over- or undercharged, which has a negative impact on efficiency. Unfortunately, many service technicians don’t take the time to diagnose or correct those problems; they typically get the system working and move on to the next service call. To measure charge correctly, airflow must be in the recommended range, and few technicians test airflow as a matter of course. There are very specific ways to measure refrigerant charge during unit operation. Depending on the type of unit, the superheat or subcooling must be measured carefully, as it is for an air conditioner. There are also several automated systems on the market today that trained technicians can use to analyze heat pump operation. Newer high-efficiency models should also be properly charged, but they are more forgiving of varying charge conditions and their efficiency doesn’t suffer as much.		
			<p>Heat pump service</p>		
		Like furnaces, heat pumps should be serviced regularly. Basic service can be done by anyone. Air filters should be replaced once or twice a year, as needed, and the outdoor coil should be kept free of snow and debris. Regular service calls— typically every two to three years—should include testing the controls, cleaning the blower and both the indoor and the outdoor coils as needed, and checking the insulation on the refrigerant lines. To service your heat pump, try to find a contractor whose technicians are certified by North American Technician Excellence (NATE, see www.hvacradvice.com), or who demonstrates a commitment to attending manufacturers’ programs frequently. An initial service appointment should include testing and fixing airflow problems, then carefully measuring and correcting refrigerant charge. Once that has been done, service technicians generally should not attach refrigerant gauges to the system unless the system performance drops off or there is other evidence that something is wrong. Refrigerant does not escape unless there is a leak.		
										<img src="/wp-content/uploads/2018/07/Heating_Pic4.png" title="Heating_Pic4" alt="Heating_Pic4" />											
										<img src="/wp-content/uploads/2018/07/Heatin_Pic5.png" title="Heatin_Pic5" alt="Heatin_Pic5" />											
			<h1>Weatherstripping Doors and Hatches</h1>		
		<p>Most modern doors and windows have good weatherstripping built in, but older ones usually don’t. In addition, many homes have at least one less-finished, or even makeshift, door or hatchway as part of the thermal boundary.</p>		
			<h4>Energy New England</h4>		
					<ul>
							<li >
										100 Foxborough Blvd., Suite 110 </br>Foxborough, MA 02035
									</li>
								<li >
										508-698-1200
									</li>
								<li >
										508-698-0222
									</li>
						</ul>
					<ul>
							<li >
					<a href="mailto:solutions@ene.org​">						
										solutions@ene.org
											</a>
									</li>
								<li >
					<a href="https://ene.org/">						
										www.ene.org
											</a>
									</li>
						</ul>
			<h4>Website</h4>		
					<ul>
							<li >
					<a href="https://ee.ene.org/">					Home
											</a>
									</li>
								<li >
					<a href="https://ee.ene.org/energy-assessment/">					Energy Assessment
											</a>
									</li>
								<li >
					<a href="https://ee.ene.org/recommendations/">					Recommendations
											</a>
									</li>
								<li >
					<a href="https://ee.ene.org/towns-we-serve/">					Town We Serve
											</a>
									</li>
								<li >
					<a href="https://ee.ene.org/home-advisor/">					Home Advisor
											</a>
									</li>
								<li >
					<a href="#">					Shop
											</a>
									</li>
								<li >
					<a href="https://ee.ene.org/contact/">					Contact
											</a>
									</li>
						</ul>
			<h4>social media</h4>		
							<a href="https://www.linkedin.com/company/energy-new-england/" target="_blank">
					Linkedin
				</a>