536:. The primary gain in efficiency for a condensing gas furnace, as compared to a mid-efficiency forced-air or forced-draft furnace, is the capture of latent heat from the exhaust gases in the secondary heat exchanger. The secondary heat exchanger removes most of the heat energy from the exhaust gas, actually condensing water vapour and other chemicals (which form a mild acid) as it operates. The vent pipes, also known as the exhaust system, are often installed using PVC pipe instead of metal venting pipe to prevent corrosion, but this will vary based on geographical location of the installation and local regulations. The draft inducer allows for the exhaust piping to be routed vertically or horizontally as it exits the structure. A typical installation arrangement for high-efficiency furnaces includes a fresh air intake (supply) pipe that brings fresh air from outside the home to the furnace combustion unit. Normally the fresh combustion air is routed alongside the exhaust PVC during installation and the pipes exit through a sidewall of the home in the same location. High efficiency furnaces typically deliver a 25% to 35% fuel savings over a 60%
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The first category of furnaces is natural draft, atmospheric burner furnaces. These furnaces consisted of cast-iron or riveted-steel heat exchangers built within an outer shell of brick, masonry, or steel. The heat exchangers were vented through brick or masonry chimneys. Air circulation depended on
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Air convection heating systems have been in use for over a century. Older systems rely on a passive air circulation system where the greater density of cooler air causes it to sink into the furnace area below, through air return registers in the floor, and the lesser density of warmed air causes it
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that accumulated in the bottom of the burner area. In later years, these furnaces were adapted with electric blowers to aid air distribution and speed moving heat into the home. Gas and oil-fired systems were usually controlled by a thermostat inside the home, while most wood and coal-fired furnaces
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of the ductwork, the arrangement of ducts can be far more flexible than the octopus of old. In
American practice, separate ducts collect cool air to be returned to the furnace. At the furnace, cool air passes into the furnace, usually through an air filter, through the blower, then through the heat
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One of the benefits to a single-stage furnace is typically the cost for installation. Single-stage furnaces are relatively inexpensive since the technology is rather simple. However, the simplicity of single-stage gas furnaces come at the cost of blower motor noise and mechanical inefficiency. The
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The second category of furnace is the forced-air having atmospheric burner style with a cast-iron or sectional steel heat exchanger. Through the 1950s and 1960s, this style of furnace was used to replace the big, natural draft systems, and was sometimes installed on the existing gravity duct work.
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The system was simple, had few controls, a single automatic gas valve, and no blower. These furnaces could be made to work with any fuel simply by adapting the burner area. They have been operated with wood, coke, coal, trash, paper, natural gas, fuel oil as well as whale oil for a brief period at
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have been sealed using mastic or foil duct tape, the ductwork is likely to have a high leakage of conditioned air, possibly into unconditioned spaces. Another cause of wasted energy is the installation of ductwork in unheated areas, such as attics and crawl spaces; or ductwork of air conditioning
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blower motors on these single-stage furnaces consume more energy overall because, regardless of the heating requirements of the space, the fan and blower motors operate at a fixed-speed. Due to its One-Speed operation, a single-stage furnace is also called a single-speed furnace.
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A two-stage furnace has to do two stage full speed and half (or reduced) speed. Depending on the demanded heat, they can run at a lower speed most of the time. They can be quieter, move the air at less velocity, and will better keep the desired temperature in the house.
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The fourth category of furnace is the high-efficiency condensing gas furnace. High efficiency condensing gas furnaces typically achieve between 90% and 98% AFUE. A condensing gas furnace includes a sealed combustion area, combustion draft inducer and a secondary
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to rise in the ductwork; the two forces acting together to drive air circulation in a system termed 'gravity-fed'. The layout of these 'octopus’ furnaces and their duct systems is optimized with various diameters of large dampered ducts.
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The heated air was moved by blowers which were belted driven and designed for a wide range of speeds. These furnaces were still big and bulky compared to modern furnaces, and had heavy-steel exteriors with bolt-on removable panels.
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The furnace transfers heat to the living space of the building through an intermediary distribution system. If the distribution is through hot water (or other fluid) or through steam, then the furnace is more commonly called a
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A modulating furnace can modulate the heat output and air velocity nearly continuously, depending on the demanded heat and outside temperature. This means that it only works as much as necessary and therefore saves energy.
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A single-stage furnace has only one stage of operation, it is either on or off. This means that it is relatively noisy, always running at the highest speed, and always pumping out the hottest air at the highest velocity.
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and multi-speed blower. These furnaces were physically much more compact than the previous styles. They were equipped with combustion air blowers that would pull air through the heat exchanger which greatly increased
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large, upwardly pitched pipes constructed of wood or metal. The pipes would channel the warm air into floor or wall vents inside the home. This method of heating worked because
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373:. Heating appliances that use steam or hot water as the fluid are normally referred to as a residential steam boilers or residential hot water boilers. The most common
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while allowing the heat exchangers to become smaller. These furnaces may have multi-speed blowers and were designed to work with central air-conditioning systems.
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heating is used, especially where the cost of electricity is low or the primary purpose is for air conditioning. Modern high-efficiency furnaces can be up to 98%
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and operate without a chimney, with a typical gas furnace being about 80% efficient. Waste gas and heat are mechanically ventilated through either metal
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had no electrical connection and were controlled by the amount of fuel in the burner and position of the fresh-air damper on the burner access door.
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Furnaces can be classified into four general categories, based on efficiency and design, natural draft, forced-air, forced draft, and condensing.
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597:. One advantage of a boiler is that the furnace can provide hot water for bathing and washing dishes, rather than requiring a separate
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601:. One disadvantage to this type of application is when the boiler breaks down, neither heating nor domestic hot water are available.
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413:(PVC) pipes that can be vented through the side or roof of the structure. Fuel efficiency in a gas furnace is measured in
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the turn of the century. Furnaces that used solid fuels required daily maintenance to remove ash and
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The third category of furnace is the forced draft, mid-efficiency furnace with a steel
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ASHRAE Handbook. Heating, ventilating and air-conditioning systems and equipment
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745:. Vol. 11 (11th ed.). Cambridge University Press. p. 358.
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Fiveland, W.A.; Crosbie, A.L.; Smith, A.M.; Smith, T.F., eds. (1991).
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source for modern furnaces in North
America and much of Europe is
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637:, simply by adding a cooling coil at the outlet of the furnace.
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By comparison, most modern "warm air" furnaces typically use a
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deal primarily with the United States and do not represent a
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exchanger of the furnace, whence it is blown throughout the
777:"Handbook on Single, Multi & Variable Speed Furnaces"
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would range anywhere from just over 50% to upward of 65%
457:
Diagram of natural draft gas furnace, early 20th century.
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2004:
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Engineering calculations in radiative heat transfer
114:. Unsourced material may be challenged and removed.
879:(2nd ed.). Instrument Society of America.
703:Johnson, Bill; Standiford, Kevin (2008-08-28).
998:Lieberman, P.; Lieberman, Elizabeth T (2003).
1033:
261:The examples and perspective in this article
8:
841:. American Society of Mechanical Engineers.
624:heat. Because the fan easily overcomes the
77:Learn how and when to remove these messages
1800:High efficiency glandless circulating pump
1049:Heating, ventilation, and air conditioning
1040:
1026:
1018:
612:Forced-air gas furnace, design circa 1991.
860:(1st ed.). Gulf Publishing Company.
317:Learn how and when to remove this message
299:Learn how and when to remove this message
236:Learn how and when to remove this message
174:Learn how and when to remove this message
2234:Mold growth, assessment, and remediation
858:Handbook of valves, piping and pipelines
199:This article includes a list of general
977:Perry, R.H.; Green, D.W., eds. (1997).
898:. Mechanical Engineering Publications.
839:Fundamentals of radiation heat transfer
695:
417:(Annual Fuel Utilization Efficiency).
2107:Programmable communicating thermostat
7:
2229:Mechanical, electrical, and plumbing
980:Perry's Chemical Engineers' Handbook
896:The valve and actuator user's manual
822:(1st ed.). Pergamon Press Ltd.
649:systems in attics in warm climates.
381:; other common fuel sources include
112:adding citations to reliable sources
2090:Minimum efficiency reporting value
1000:Working Guide to Process Equipment
932:Goldstick, R.; Thumann, A (1986).
915:Calculations in furnace technology
588:"Octopus" furnace with oil burner.
205:it lacks sufficient corresponding
25:
2132:Standard temperature and pressure
1845:Packaged terminal air conditioner
1381:Passive daytime radiative cooling
1110:Heat pump and refrigeration cycle
934:Principles of waste heat recovery
709:. Cengage Learning. p. 116.
58:This article has multiple issues.
27:Device used for heating buildings
1201:Absorption-compression heat pump
917:(1st ed.). Pergamon Press.
252:
190:
88:
47:
2096:Normal temperature and pressure
1476:Vapor-compression refrigeration
793:from the original on 2020-07-05
544:Types of furnace output control
99:needs additional citations for
66:or discuss these issues on the
2428:Residential heating appliances
894:Whitehouse, R.C., ed. (1993).
816:Gray, W.A.; Muller, R (1974).
123:"Furnace" central heating
1:
2244:Testing, adjusting, balancing
2188:Building information modeling
2183:Building services engineering
1760:Ground-coupled heat exchanger
1288:Demand controlled ventilation
1236:Building insulation materials
1002:(2nd ed.). McGraw-Hill.
983:(7th ed.). McGraw-Hill.
1805:High-pressure cut-off switch
1356:Ice storage air conditioning
1277:Dedicated outdoor air system
706:Practical Heating Technology
2148:Thermostatic radiator valve
1950:Thermostatic radiator valve
1461:Underfloor air distribution
1396:Radiant heating and cooling
1314:Energy recovery ventilation
1226:Automobile air conditioning
1090:Domestic energy consumption
877:Improving boiler efficiency
775:Ahmed, Rifat (2020-06-01).
385:(liquefied petroleum gas),
275:, discuss the issue on the
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2297:Institute of Refrigeration
2178:Architectural technologist
1650:Electrostatic precipitator
875:Dukelow, Samuel G (1985).
640:Air is circulated through
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36:
29:
2350:Volatile organic compound
2209:Environmental engineering
2173:Architectural engineering
1975:Ultra-low particulate air
1560:Automatic balancing valve
1488:Variable refrigerant flow
1340:Heat recovery ventilation
1283:Deep water source cooling
679:Outdoor wood-fired boiler
2397:Template:Home automation
2219:Kitchen exhaust cleaning
1915:Solar-assisted heat pump
1515:Air conditioner inverter
1294:Displacement ventilation
1185:Vapour pressure of water
1170:Thermal destratification
659:Phase-out of gas boilers
32:Furnace (disambiguation)
2392:World Refrigeration Day
2239:Refrigerant reclamation
2168:Architectural acoustics
2112:Programmable thermostat
2044:Clean air delivery rate
1940:Thermal expansion valve
1855:Pressurisation ductwork
1765:Ground source heat pump
1206:Absorption refrigerator
742:Encyclopædia Britannica
220:more precise citations.
18:Furnace (house heating)
2382:Glossary of HVAC terms
2344:Sick building syndrome
2224:Mechanical engineering
1935:Smoke exhaust ductwork
1366:Mixed-mode ventilation
913:Davies, Clive (1970).
856:Warring, R. H (1982).
758:"Furnaces and Boilers"
613:
589:
522:
458:
425:The name derives from
359:central heating system
334:
39:Boiler (water heating)
2402:Template:Solar energy
2080:Intelligent buildings
2039:Carbon dioxide sensor
1426:Room air distribution
1246:Central solar heating
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399:electrical resistance
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2438:Industrial processes
2204:Duct leakage testing
2194:Deep energy retrofit
2138:Thermographic camera
2075:Infrared thermometer
1550:Air source heat pump
1499:Water heat recycling
1065:Air changes per hour
756:US Dept. of Energy.
521:A condensing furnace
345:), referred to as a
281:create a new article
273:improve this article
108:improve this article
30:For other uses, see
2433:Industrial furnaces
2070:HVAC control system
2060:Home energy monitor
2034:Building automation
1820:Inverter compressor
1482:Variable air volume
1391:Passive ventilation
1361:Kitchen ventilation
1261:Constant air volume
1231:Autonomous building
2333:Indoor air quality
2277:ASTM International
2214:Hydronic balancing
1991:Wood-burning stove
1870:Radiator reflector
1655:Evaporative cooler
1466:Underfloor heating
1451:Thermal insulation
936:. Fairmont Press.
762:US Dept. of Energy
614:
590:
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459:
411:polyvinyl chloride
393:and in rare cases
335:
2443:Firing techniques
2410:
2409:
2326:Health and safety
1905:Scroll compressor
1860:Process duct work
1615:Convection heater
1610:Condensing boiler
1540:Air-mixing plenum
1436:Solar combisystem
1272:Cross ventilation
1075:Building envelope
674:Jetstream furnace
664:Condensing boiler
580:Heat distribution
527:Condensing boiler
486:Energy efficiency
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283:, as appropriate.
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16:(Redirected from
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2372:Building science
2127:Smart thermostat
2122:Room temperature
1705:Fireplace insert
1411:Radon mitigation
1309:Electric heating
1304:District heating
1299:District cooling
1216:Air conditioning
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954:. ASHRAE. 1992.
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1981:Whole-house fan
1895:Run-around coil
1890:Reversing valve
1835:Mechanical room
1825:Kerosene heater
1815:Infrared heater
1745:Gasoline heater
1685:Fan filter unit
1600:Condensate pump
1585:Centrifugal fan
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1406:Radiant heating
1401:Radiant cooling
1376:Passive cooling
1371:Microgeneration
1241:Central heating
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1438:
1433:
1431:Solar air heat
1428:
1423:
1421:Renewable heat
1418:
1413:
1408:
1403:
1398:
1393:
1388:
1383:
1378:
1373:
1368:
1363:
1358:
1353:
1348:
1343:
1337:
1332:
1330:Forced-air gas
1327:
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1296:
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1188:
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1182:
1180:Thermodynamics
1177:
1172:
1167:
1162:
1157:
1152:
1150:Psychrometrics
1147:
1142:
1137:
1132:
1127:
1122:
1117:
1112:
1107:
1105:Gas compressor
1102:
1100:Fluid dynamics
1097:
1092:
1087:
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1077:
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1053:
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891:
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872:
866:
853:
847:
834:
828:
812:
810:
807:
804:
803:
784:Green Leaf Air
767:
748:
733:, ed. (1911).
731:Chisholm, Hugh
722:
716:978-1418080396
715:
694:
693:
691:
688:
687:
686:
684:Masonry heater
681:
676:
671:
669:Forced-air gas
666:
661:
654:
651:
581:
578:
572:
569:
563:
560:
550:
547:
545:
542:
534:heat exchanger
525:Main article:
514:
511:
502:heat exchanger
497:
494:
480:
477:
464:warm air rises
450:
447:
442:
439:
433:, which means
422:
419:
333:An oil furnace
325:
324:
307:
306:
267:of the subject
265:worldwide view
260:
258:
251:
244:
243:
198:
196:
189:
182:
181:
96:
94:
87:
82:
56:
55:
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46:
26:
24:
14:
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10:
9:
6:
4:
3:
2:
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2268:
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2259:
2257:
2255:organizations
2251:
2245:
2242:
2240:
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2235:
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2227:
2225:
2222:
2220:
2217:
2215:
2212:
2210:
2207:
2205:
2202:
2200:
2199:Duct cleaning
2197:
2195:
2192:
2189:
2186:
2184:
2181:
2179:
2176:
2174:
2171:
2169:
2166:
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2155:
2149:
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2141:
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2136:
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2115:
2113:
2110:
2108:
2105:
2103:
2100:
2097:
2094:
2091:
2088:
2086:
2083:
2081:
2078:
2076:
2073:
2071:
2068:
2066:
2063:
2061:
2058:
2056:
2053:
2051:
2050:Control valve
2048:
2045:
2042:
2040:
2037:
2035:
2032:
2030:
2027:
2025:
2022:
2020:
2017:
2015:
2012:
2011:
2009:
2003:
1997:
1994:
1992:
1989:
1987:
1984:
1982:
1979:
1976:
1973:
1971:
1970:Turning vanes
1968:
1966:
1963:
1961:
1958:
1956:
1953:
1951:
1948:
1946:
1945:Thermal wheel
1943:
1941:
1938:
1936:
1933:
1931:
1928:
1926:
1923:
1921:
1918:
1916:
1913:
1911:
1910:Solar chimney
1908:
1906:
1903:
1901:
1898:
1896:
1893:
1891:
1888:
1886:
1883:
1881:
1878:
1876:
1873:
1871:
1868:
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1706:
1703:
1701:
1698:
1696:
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1691:
1688:
1686:
1683:
1681:
1680:Fan coil unit
1678:
1676:
1673:
1671:
1668:
1666:
1663:
1661:
1658:
1656:
1653:
1651:
1648:
1646:
1643:
1641:
1638:
1636:
1633:
1631:
1628:
1626:
1625:Cooling tower
1623:
1621:
1618:
1616:
1613:
1611:
1608:
1606:
1603:
1601:
1598:
1596:
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1518:
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1513:
1512:
1510:
1506:
1500:
1497:
1495:
1492:
1489:
1486:
1483:
1480:
1477:
1474:
1472:
1471:Vapor barrier
1469:
1467:
1464:
1462:
1459:
1457:
1454:
1452:
1449:
1447:
1446:Solar heating
1444:
1442:
1441:Solar cooling
1439:
1437:
1434:
1432:
1429:
1427:
1424:
1422:
1419:
1417:
1416:Refrigeration
1414:
1412:
1409:
1407:
1404:
1402:
1399:
1397:
1394:
1392:
1389:
1387:
1386:Passive house
1384:
1382:
1379:
1377:
1374:
1372:
1369:
1367:
1364:
1362:
1359:
1357:
1354:
1352:
1349:
1347:
1344:
1341:
1338:
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1331:
1328:
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1318:
1315:
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1310:
1307:
1305:
1302:
1300:
1297:
1295:
1292:
1289:
1286:
1284:
1281:
1278:
1275:
1273:
1270:
1268:
1265:
1262:
1259:
1257:
1256:Chilled water
1254:
1252:
1249:
1247:
1244:
1242:
1239:
1237:
1234:
1232:
1229:
1227:
1224:
1222:
1219:
1217:
1214:
1212:
1209:
1207:
1204:
1202:
1199:
1198:
1196:
1192:
1186:
1183:
1181:
1178:
1176:
1173:
1171:
1168:
1166:
1163:
1161:
1158:
1156:
1155:Sensible heat
1153:
1151:
1148:
1146:
1143:
1141:
1138:
1136:
1135:Noise control
1133:
1131:
1128:
1126:
1123:
1121:
1118:
1116:
1115:Heat transfer
1113:
1111:
1108:
1106:
1103:
1101:
1098:
1096:
1093:
1091:
1088:
1086:
1083:
1081:
1078:
1076:
1073:
1071:
1068:
1066:
1063:
1062:
1060:
1054:
1050:
1043:
1038:
1036:
1031:
1029:
1024:
1023:
1020:
1011:
1009:0-07-139087-1
1005:
1001:
996:
992:
990:0-07-049841-5
986:
982:
981:
975:
971:
967:
963:
961:0-910110-80-8
957:
953:
949:
945:
943:0-88173-015-7
939:
935:
930:
926:
924:0-08-013366-5
920:
916:
911:
907:
905:0-85298-805-2
901:
897:
892:
888:
886:0-87664-852-9
882:
878:
873:
869:
867:0-87201-885-7
863:
859:
854:
850:
848:0-7918-0729-0
844:
840:
835:
831:
829:0-08-017786-7
825:
821:
818:
814:
813:
808:
789:
785:
778:
771:
768:
763:
759:
752:
749:
744:
743:
737:
732:
726:
723:
718:
712:
708:
707:
699:
696:
689:
685:
682:
680:
677:
675:
672:
670:
667:
665:
662:
660:
657:
656:
652:
650:
647:
643:
638:
636:
632:
627:
623:
619:
610:
606:
602:
600:
596:
586:
579:
577:
570:
568:
561:
559:
555:
548:
543:
541:
539:
535:
528:
519:
512:
510:
508:
503:
495:
493:
491:
487:
478:
476:
473:
467:
465:
455:
449:Natural draft
448:
446:
440:
438:
436:
432:
428:
420:
418:
416:
412:
408:
404:
400:
396:
392:
388:
384:
380:
376:
372:
368:
364:
360:
356:
352:
348:
344:
340:
331:
321:
318:
303:
300:
292:
289:November 2022
282:
278:
274:
268:
266:
259:
250:
249:
240:
237:
229:
219:
215:
209:
208:
202:
197:
188:
187:
178:
175:
167:
156:
153:
149:
146:
142:
139:
135:
132:
128:
125: –
124:
120:
119:Find sources:
113:
109:
103:
102:
97:This article
95:
91:
86:
85:
80:
78:
71:
70:
65:
64:
59:
54:
45:
44:
40:
33:
19:
2377:Fireproofing
2161:and services
2157:Professions,
2055:Gas detector
1955:Trickle vent
1930:Smoke damper
1925:Smoke canopy
1920:Space heater
1850:Plenum space
1785:Heating film
1665:Exhaust hood
1635:Dehumidifier
1575:Blast damper
1570:Barrier pipe
1545:Air purifier
1456:Thermosiphon
1335:Free cooling
1251:Chilled beam
1175:Thermal mass
1160:Stack effect
1145:Particulates
1125:Infiltration
1056:Fundamental
999:
978:
951:
933:
914:
895:
876:
857:
838:
820:
817:
795:. Retrieved
783:
770:
761:
751:
740:
725:
705:
698:
639:
615:
603:
599:water heater
591:
574:
565:
556:
552:
549:Single-stage
530:
499:
496:Forced draft
482:
468:
460:
444:
430:
424:
350:
346:
338:
336:
313:
295:
286:
262:
232:
223:
204:
170:
161:
151:
144:
137:
130:
118:
106:Please help
101:verification
98:
74:
67:
61:
60:Please help
57:
2387:Warm Spaces
2029:Blower door
2007:and control
2005:Measurement
1986:Windcatcher
1960:Trombe wall
1900:Sail switch
1880:Refrigerant
1875:Recuperator
1750:Grease duct
1710:Freeze stat
1695:Fire damper
1565:Back boiler
1535:Air ionizer
1530:Air handler
1494:Ventilation
1346:Hybrid heat
1211:Air barrier
1130:Latent heat
379:natural gas
218:introducing
2423:Fireplaces
2417:Categories
2143:Thermostat
2065:Humidistat
1996:Zone valve
1965:TurboSwing
1840:Oil heater
1810:Humidifier
1740:Gas heater
1690:Fan heater
1660:Evaporator
1645:Economizer
1620:Compressor
1525:Air filter
1508:Components
1325:Forced-air
1221:Antifreeze
1194:Technology
1140:Outgassing
1080:Convection
809:References
797:2020-08-17
626:resistance
622:forced-air
571:Modulating
513:Condensing
479:Forced-air
472:"clinkers"
441:Categories
226:April 2014
201:references
134:newspapers
63:improve it
37:See also:
2253:Industry
2102:OpenTherm
1780:Heat pump
1775:Heat pipe
1725:Fume hood
1700:Fireplace
1605:Condenser
1555:Attic fan
1351:Hydronics
970:1078-6066
562:Two-stage
540:furnace.
421:Etymology
409:pipes or
403:efficient
369:, or hot
277:talk page
164:July 2007
69:talk page
2360:See also
2085:LonWorks
2019:Aquastat
1885:Register
1865:Radiator
1520:Air door
1320:Firestop
1120:Humidity
1095:Enthalpy
1085:Dilution
1070:Bake-out
1058:concepts
788:Archived
653:See also
642:ductwork
631:building
387:fuel oil
271:You may
2159:trades,
1730:Furnace
1595:Chiller
1267:Coolant
339:furnace
214:improve
148:scholar
2312:SMACNA
2272:ASHRAE
2092:(MERV)
2046:(CADR)
2024:BACnet
1977:(ULPA)
1830:Louver
1755:Grille
1630:Damper
1580:Boiler
1478:(VCRS)
1279:(DOAS)
1006:
987:
968:
958:
940:
921:
902:
883:
864:
845:
826:
713:
646:plenum
595:boiler
431:fornax
351:boiler
347:heater
203:, but
150:
143:
136:
129:
121:
2352:(VOC)
2346:(SBS)
2335:(IAQ)
2292:CIBSE
2287:BSRIA
2190:(BIM)
2134:(STP)
2098:(NTP)
1720:Freon
1490:(VRF)
1484:(VAV)
1342:(HRV)
1316:(ERV)
1290:(DCV)
1263:(CAV)
791:(PDF)
780:(PDF)
690:Notes
429:word
427:Latin
371:water
367:steam
279:, or
155:JSTOR
141:books
2307:LEED
2267:AMCA
2262:AHRI
1795:HEPA
1715:Flue
1640:Duct
1004:ISBN
985:ISBN
966:ISSN
956:ISBN
938:ISBN
919:ISBN
900:ISBN
881:ISBN
862:ISBN
843:ISBN
824:ISBN
711:ISBN
538:AFUE
490:AFUE
435:oven
415:AFUE
407:flue
395:coal
391:wood
375:fuel
127:news
2317:UMC
2302:IIR
2282:BRE
1675:Fan
618:fan
383:LPG
363:air
353:in
349:or
110:by
2419::
964:.
786:.
782:.
760:.
739:.
466:.
437:.
389:,
365:,
337:A
72:.
1041:e
1034:t
1027:v
1012:.
993:.
972:.
946:.
927:.
908:.
889:.
870:.
851:.
832:.
800:.
764:.
719:.
341:(
320:)
314:(
302:)
296:(
291:)
287:(
269:.
239:)
233:(
228:)
224:(
210:.
177:)
171:(
166:)
162:(
152:·
145:·
138:·
131:·
104:.
79:)
75:(
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
