525:. 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
362:. 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.
481:. This style furnace still used large, masonry or brick chimneys for flues and was eventually designed to accommodate air-conditioning systems.
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586:. 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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350:. Furnaces are permanently installed to provide heat to an interior space through intermediary fluid movement, which may be
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402:(PVC) pipes that can be vented through the side or roof of the structure. Fuel efficiency in a gas furnace is measured in
346:, is an appliance used to generate heat for all or part of a building. Furnaces are mostly used as a major component of a
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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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622:. One major advantage of this type of system is that it also enables easy installation of central
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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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734:. 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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626:, 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
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766:"Handbook on Single, Multi & Variable Speed Furnaces"
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would range anywhere from just over 50% to upward of 65%
446:
Diagram of natural draft gas furnace, early 20th century.
351:
920:
808:
Engineering calculations in radiative heat transfer
804:
103:. Unsourced material may be challenged and removed.
532:
863:
691:
2403:
868:(2nd ed.). Instrument Society of America.
692:Johnson, Bill; Standiford, Kevin (2008-08-28).
987:Lieberman, P.; Lieberman, Elizabeth T (2003).
744:
1022:
901:
844:
250:The examples and perspective in this article
830:. American Society of Mechanical Engineers.
613:heat. Because the fan easily overcomes the
66:Learn how and when to remove these messages
1789:High efficiency glandless circulating pump
1038:Heating, ventilation, and air conditioning
1029:
1015:
965:
882:
601:Forced-air gas furnace, design circa 1991.
849:(1st ed.). Gulf Publishing Company.
306:Learn how and when to remove this message
288:Learn how and when to remove this message
225:Learn how and when to remove this message
163:Learn how and when to remove this message
2223:Mold growth, assessment, and remediation
847:Handbook of valves, piping and pipelines
718:
596:
572:
505:
441:
317:
188:This article includes a list of general
966:Perry, R.H.; Green, D.W., eds. (1997).
887:. Mechanical Engineering Publications.
828:Fundamentals of radiation heat transfer
2404:
406:(Annual Fuel Utilization Efficiency).
2096:Programmable communicating thermostat
1010:
763:
2218:Mechanical, electrical, and plumbing
969:Perry's Chemical Engineers' Handbook
885:The valve and actuator user's manual
811:(1st ed.). Pergamon Press Ltd.
638:systems in attics in warm climates.
568:
370:; other common fuel sources include
236:
174:
101:adding citations to reliable sources
72:
31:
13:
2079:Minimum efficiency reporting value
989:Working Guide to Process Equipment
921:Goldstick, R.; Thumann, A (1986).
904:Calculations in furnace technology
577:"Octopus" furnace with oil burner.
194:it lacks sufficient corresponding
14:
2443:
2121:Standard temperature and pressure
1834:Packaged terminal air conditioner
1370:Passive daytime radiative cooling
1099:Heat pump and refrigeration cycle
923:Principles of waste heat recovery
698:. Cengage Learning. p. 116.
47:This article has multiple issues.
16:Device used for heating buildings
1190:Absorption-compression heat pump
906:(1st ed.). Pergamon Press.
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241:
179:
77:
36:
2085:Normal temperature and pressure
1465:Vapor-compression refrigeration
782:from the original on 2020-07-05
537:
533:Types of furnace output control
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88:needs additional citations for
55:or discuss these issues on the
2417:Residential heating appliances
883:Whitehouse, R.C., ed. (1993).
805:Gray, W.A.; Muller, R (1974).
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712:
685:
112:"Furnace" central heating
1:
2233:Testing, adjusting, balancing
2177:Building information modeling
2172:Building services engineering
1749:Ground-coupled heat exchanger
1277:Demand controlled ventilation
1225:Building insulation materials
991:(2nd ed.). McGraw-Hill.
972:(7th ed.). McGraw-Hill.
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559:
501:
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1794:High-pressure cut-off switch
1345:Ice storage air conditioning
1266:Dedicated outdoor air system
695:Practical Heating Technology
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409:
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2137:Thermostatic radiator valve
1939:Thermostatic radiator valve
1450:Underfloor air distribution
1385:Radiant heating and cooling
1303:Energy recovery ventilation
1215:Automobile air conditioning
1079:Domestic energy consumption
866:Improving boiler efficiency
764:Ahmed, Rifat (2020-06-01).
641:
374:(liquefied petroleum gas),
264:, discuss the issue on the
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2286:Institute of Refrigeration
2167:Architectural technologist
1639:Electrostatic precipitator
864:Dukelow, Samuel G (1985).
629:Air is circulated through
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18:
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2339:Volatile organic compound
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2198:Environmental engineering
2162:Architectural engineering
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1964:Ultra-low particulate air
1549:Automatic balancing valve
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1477:Variable refrigerant flow
1329:Heat recovery ventilation
1272:Deep water source cooling
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668:Outdoor wood-fired boiler
2386:Template:Home automation
2208:Kitchen exhaust cleaning
1904:Solar-assisted heat pump
1504:Air conditioner inverter
1283:Displacement ventilation
1174:Vapour pressure of water
1159:Thermal destratification
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648:Phase-out of gas boilers
21:Furnace (disambiguation)
2381:World Refrigeration Day
2228:Refrigerant reclamation
2157:Architectural acoustics
2101:Programmable thermostat
2033:Clean air delivery rate
1929:Thermal expansion valve
1844:Pressurisation ductwork
1754:Ground source heat pump
1195:Absorption refrigerator
731:Encyclopædia Britannica
209:more precise citations.
2371:Glossary of HVAC terms
2333:Sick building syndrome
2213:Mechanical engineering
1924:Smoke exhaust ductwork
1355:Mixed-mode ventilation
902:Davies, Clive (1970).
845:Warring, R. H (1982).
747:"Furnaces and Boilers"
602:
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511:
447:
414:The name derives from
348:central heating system
323:
28:Boiler (water heating)
2391:Template:Solar energy
2069:Intelligent buildings
2028:Carbon dioxide sensor
1415:Room air distribution
1235:Central solar heating
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388:electrical resistance
321:
2427:Industrial processes
2193:Duct leakage testing
2183:Deep energy retrofit
2127:Thermographic camera
2064:Infrared thermometer
1539:Air source heat pump
1488:Water heat recycling
1054:Air changes per hour
745:US Dept. of Energy.
510:A condensing furnace
334:), referred to as a
270:create a new article
262:improve this article
97:improve this article
19:For other uses, see
2422:Industrial furnaces
2059:HVAC control system
2049:Home energy monitor
2023:Building automation
1809:Inverter compressor
1471:Variable air volume
1380:Passive ventilation
1350:Kitchen ventilation
1250:Constant air volume
1220:Autonomous building
2322:Indoor air quality
2266:ASTM International
2203:Hydronic balancing
1980:Wood-burning stove
1859:Radiator reflector
1644:Evaporative cooler
1455:Underfloor heating
1440:Thermal insulation
925:. Fairmont Press.
751:US Dept. of Energy
603:
579:
512:
448:
400:polyvinyl chloride
382:and in rare cases
324:
2432:Firing techniques
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2315:Health and safety
1894:Scroll compressor
1849:Process duct work
1604:Convection heater
1599:Condensing boiler
1529:Air-mixing plenum
1425:Solar combisystem
1261:Cross ventilation
1064:Building envelope
663:Jetstream furnace
653:Condensing boiler
569:Heat distribution
516:Condensing boiler
475:Energy efficiency
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2116:Smart thermostat
2111:Room temperature
1694:Fireplace insert
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1298:Electric heating
1293:District heating
1288:District cooling
1205:Air conditioning
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386:. In some areas
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1970:Whole-house fan
1884:Run-around coil
1879:Reversing valve
1824:Mechanical room
1814:Kerosene heater
1804:Infrared heater
1734:Gasoline heater
1674:Fan filter unit
1589:Condensate pump
1574:Centrifugal fan
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1390:Radiant cooling
1365:Passive cooling
1360:Microgeneration
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1462:
1457:
1452:
1447:
1442:
1437:
1432:
1427:
1422:
1420:Solar air heat
1417:
1412:
1410:Renewable heat
1407:
1402:
1397:
1392:
1387:
1382:
1377:
1372:
1367:
1362:
1357:
1352:
1347:
1342:
1337:
1332:
1326:
1321:
1319:Forced-air gas
1316:
1311:
1306:
1300:
1295:
1290:
1285:
1280:
1274:
1269:
1263:
1258:
1253:
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1207:
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1186:
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1179:
1177:
1176:
1171:
1169:Thermodynamics
1166:
1161:
1156:
1151:
1146:
1141:
1139:Psychrometrics
1136:
1131:
1126:
1121:
1116:
1111:
1106:
1101:
1096:
1094:Gas compressor
1091:
1089:Fluid dynamics
1086:
1081:
1076:
1071:
1066:
1061:
1056:
1050:
1048:
1042:
1041:
1034:
1033:
1026:
1019:
1011:
1004:
1003:
997:
984:
978:
963:
949:
937:
931:
918:
912:
899:
893:
880:
874:
861:
855:
842:
836:
823:
817:
801:
799:
796:
793:
792:
773:Green Leaf Air
756:
737:
722:, ed. (1911).
720:Chisholm, Hugh
711:
705:978-1418080396
704:
683:
682:
680:
677:
676:
675:
673:Masonry heater
670:
665:
660:
658:Forced-air gas
655:
650:
643:
640:
570:
567:
561:
558:
552:
549:
539:
536:
534:
531:
523:heat exchanger
514:Main article:
503:
500:
491:heat exchanger
486:
483:
469:
466:
453:warm air rises
439:
436:
431:
428:
422:, which means
411:
408:
322:An oil furnace
314:
313:
296:
295:
256:of the subject
254:worldwide view
249:
247:
240:
233:
232:
187:
185:
178:
171:
170:
85:
83:
76:
71:
45:
44:
42:
35:
15:
9:
6:
4:
3:
2:
2444:
2433:
2430:
2428:
2425:
2423:
2420:
2418:
2415:
2413:
2410:
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2407:
2392:
2389:
2387:
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2379:
2377:
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2364:
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2320:
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2307:
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2299:
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2279:
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2272:
2269:
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2259:
2257:
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2252:
2249:
2248:
2246:
2244:organizations
2240:
2234:
2231:
2229:
2226:
2224:
2221:
2219:
2216:
2214:
2211:
2209:
2206:
2204:
2201:
2199:
2196:
2194:
2191:
2189:
2188:Duct cleaning
2186:
2184:
2181:
2178:
2175:
2173:
2170:
2168:
2165:
2163:
2160:
2158:
2155:
2154:
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2144:
2138:
2135:
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2130:
2128:
2125:
2122:
2119:
2117:
2114:
2112:
2109:
2107:
2104:
2102:
2099:
2097:
2094:
2092:
2089:
2086:
2083:
2080:
2077:
2075:
2072:
2070:
2067:
2065:
2062:
2060:
2057:
2055:
2052:
2050:
2047:
2045:
2042:
2040:
2039:Control valve
2037:
2034:
2031:
2029:
2026:
2024:
2021:
2019:
2016:
2014:
2011:
2009:
2006:
2004:
2001:
2000:
1998:
1992:
1986:
1983:
1981:
1978:
1976:
1973:
1971:
1968:
1965:
1962:
1960:
1959:Turning vanes
1957:
1955:
1952:
1950:
1947:
1945:
1942:
1940:
1937:
1935:
1934:Thermal wheel
1932:
1930:
1927:
1925:
1922:
1920:
1917:
1915:
1912:
1910:
1907:
1905:
1902:
1900:
1899:Solar chimney
1897:
1895:
1892:
1890:
1887:
1885:
1882:
1880:
1877:
1875:
1872:
1870:
1867:
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1857:
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1840:
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1800:
1797:
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1715:
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1707:
1705:
1702:
1700:
1697:
1695:
1692:
1690:
1687:
1685:
1682:
1680:
1677:
1675:
1672:
1670:
1669:Fan coil unit
1667:
1665:
1662:
1660:
1657:
1655:
1652:
1650:
1647:
1645:
1642:
1640:
1637:
1635:
1632:
1630:
1627:
1625:
1622:
1620:
1617:
1615:
1614:Cooling tower
1612:
1610:
1607:
1605:
1602:
1600:
1597:
1595:
1592:
1590:
1587:
1585:
1582:
1580:
1577:
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1557:
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1547:
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1537:
1535:
1532:
1530:
1527:
1525:
1522:
1520:
1517:
1515:
1512:
1510:
1507:
1505:
1502:
1501:
1499:
1495:
1489:
1486:
1484:
1481:
1478:
1475:
1472:
1469:
1466:
1463:
1461:
1460:Vapor barrier
1458:
1456:
1453:
1451:
1448:
1446:
1443:
1441:
1438:
1436:
1435:Solar heating
1433:
1431:
1430:Solar cooling
1428:
1426:
1423:
1421:
1418:
1416:
1413:
1411:
1408:
1406:
1405:Refrigeration
1403:
1401:
1398:
1396:
1393:
1391:
1388:
1386:
1383:
1381:
1378:
1376:
1375:Passive house
1373:
1371:
1368:
1366:
1363:
1361:
1358:
1356:
1353:
1351:
1348:
1346:
1343:
1341:
1338:
1336:
1333:
1330:
1327:
1325:
1322:
1320:
1317:
1315:
1312:
1310:
1307:
1304:
1301:
1299:
1296:
1294:
1291:
1289:
1286:
1284:
1281:
1278:
1275:
1273:
1270:
1267:
1264:
1262:
1259:
1257:
1254:
1251:
1248:
1246:
1245:Chilled water
1243:
1241:
1238:
1236:
1233:
1231:
1228:
1226:
1223:
1221:
1218:
1216:
1213:
1211:
1208:
1206:
1203:
1201:
1198:
1196:
1193:
1191:
1188:
1187:
1185:
1181:
1175:
1172:
1170:
1167:
1165:
1162:
1160:
1157:
1155:
1152:
1150:
1147:
1145:
1144:Sensible heat
1142:
1140:
1137:
1135:
1132:
1130:
1127:
1125:
1124:Noise control
1122:
1120:
1117:
1115:
1112:
1110:
1107:
1105:
1104:Heat transfer
1102:
1100:
1097:
1095:
1092:
1090:
1087:
1085:
1082:
1080:
1077:
1075:
1072:
1070:
1067:
1065:
1062:
1060:
1057:
1055:
1052:
1051:
1049:
1043:
1039:
1032:
1027:
1025:
1020:
1018:
1013:
1012:
1009:
1000:
998:0-07-139087-1
994:
990:
985:
981:
979:0-07-049841-5
975:
971:
970:
964:
960:
956:
952:
950:0-910110-80-8
946:
942:
938:
934:
932:0-88173-015-7
928:
924:
919:
915:
913:0-08-013366-5
909:
905:
900:
896:
894:0-85298-805-2
890:
886:
881:
877:
875:0-87664-852-9
871:
867:
862:
858:
856:0-87201-885-7
852:
848:
843:
839:
837:0-7918-0729-0
833:
829:
824:
820:
818:0-08-017786-7
814:
810:
807:
803:
802:
778:
774:
767:
760:
752:
748:
741:
733:
732:
726:
721:
715:
707:
701:
697:
696:
688:
684:
674:
671:
669:
666:
664:
661:
659:
656:
654:
651:
649:
646:
645:
639:
636:
632:
627:
625:
621:
616:
612:
608:
599:
595:
591:
589:
585:
575:
566:
557:
548:
544:
530:
528:
524:
517:
508:
499:
497:
492:
482:
480:
476:
465:
462:
456:
454:
444:
438:Natural draft
435:
427:
425:
421:
417:
407:
405:
401:
397:
393:
389:
385:
381:
377:
373:
369:
365:
361:
357:
353:
349:
345:
341:
337:
333:
329:
320:
310:
307:
292:
289:
281:
278:November 2022
271:
267:
263:
257:
255:
248:
239:
238:
229:
226:
218:
208:
204:
198:
197:
191:
186:
177:
176:
167:
164:
156:
145:
142:
138:
135:
131:
128:
124:
121:
117:
114: –
113:
109:
108:Find sources:
102:
98:
92:
91:
86:This article
84:
80:
75:
74:
69:
67:
60:
59:
54:
53:
48:
43:
34:
33:
29:
22:
2366:Fireproofing
2150:and services
2146:Professions,
2044:Gas detector
1944:Trickle vent
1919:Smoke damper
1914:Smoke canopy
1909:Space heater
1839:Plenum space
1774:Heating film
1654:Exhaust hood
1624:Dehumidifier
1564:Blast damper
1559:Barrier pipe
1534:Air purifier
1445:Thermosiphon
1324:Free cooling
1240:Chilled beam
1164:Thermal mass
1149:Stack effect
1134:Particulates
1114:Infiltration
1045:Fundamental
988:
967:
940:
922:
903:
884:
865:
846:
827:
809:
806:
784:. Retrieved
772:
759:
750:
740:
729:
714:
694:
687:
628:
604:
592:
588:water heater
580:
563:
554:
545:
541:
538:Single-stage
519:
488:
485:Forced draft
471:
457:
449:
433:
419:
413:
339:
335:
327:
325:
302:
284:
275:
251:
221:
212:
193:
159:
150:
140:
133:
126:
119:
107:
95:Please help
90:verification
87:
63:
56:
50:
49:Please help
46:
2376:Warm Spaces
2018:Blower door
1996:and control
1994:Measurement
1975:Windcatcher
1949:Trombe wall
1889:Sail switch
1869:Refrigerant
1864:Recuperator
1739:Grease duct
1699:Freeze stat
1684:Fire damper
1554:Back boiler
1524:Air ionizer
1519:Air handler
1483:Ventilation
1335:Hybrid heat
1200:Air barrier
1119:Latent heat
368:natural gas
207:introducing
2412:Fireplaces
2406:Categories
2132:Thermostat
2054:Humidistat
1985:Zone valve
1954:TurboSwing
1829:Oil heater
1799:Humidifier
1729:Gas heater
1679:Fan heater
1649:Evaporator
1634:Economizer
1609:Compressor
1514:Air filter
1497:Components
1314:Forced-air
1210:Antifreeze
1183:Technology
1129:Outgassing
1069:Convection
798:References
786:2020-08-17
615:resistance
611:forced-air
560:Modulating
502:Condensing
468:Forced-air
461:"clinkers"
430:Categories
215:April 2014
190:references
123:newspapers
52:improve it
26:See also:
2242:Industry
2091:OpenTherm
1769:Heat pump
1764:Heat pipe
1714:Fume hood
1689:Fireplace
1594:Condenser
1544:Attic fan
1340:Hydronics
959:1078-6066
551:Two-stage
529:furnace.
410:Etymology
398:pipes or
392:efficient
358:, or hot
266:talk page
153:July 2007
58:talk page
2349:See also
2074:LonWorks
2008:Aquastat
1874:Register
1854:Radiator
1509:Air door
1309:Firestop
1109:Humidity
1084:Enthalpy
1074:Dilution
1059:Bake-out
1047:concepts
777:Archived
642:See also
631:ductwork
620:building
376:fuel oil
260:You may
2148:trades,
1719:Furnace
1584:Chiller
1256:Coolant
328:furnace
203:improve
137:scholar
2301:SMACNA
2261:ASHRAE
2081:(MERV)
2035:(CADR)
2013:BACnet
1966:(ULPA)
1819:Louver
1744:Grille
1619:Damper
1569:Boiler
1467:(VCRS)
1268:(DOAS)
995:
976:
957:
947:
929:
910:
891:
872:
853:
834:
815:
702:
635:plenum
584:boiler
420:fornax
340:boiler
336:heater
192:, but
139:
132:
125:
118:
110:
2341:(VOC)
2335:(SBS)
2324:(IAQ)
2281:CIBSE
2276:BSRIA
2179:(BIM)
2123:(STP)
2087:(NTP)
1709:Freon
1479:(VRF)
1473:(VAV)
1331:(HRV)
1305:(ERV)
1279:(DCV)
1252:(CAV)
780:(PDF)
769:(PDF)
679:Notes
418:word
416:Latin
360:water
356:steam
268:, or
144:JSTOR
130:books
2296:LEED
2256:AMCA
2251:AHRI
1784:HEPA
1704:Flue
1629:Duct
993:ISBN
974:ISBN
955:ISSN
945:ISBN
927:ISBN
908:ISBN
889:ISBN
870:ISBN
851:ISBN
832:ISBN
813:ISBN
700:ISBN
527:AFUE
479:AFUE
424:oven
404:AFUE
396:flue
384:coal
380:wood
364:fuel
116:news
2306:UMC
2291:IIR
2271:BRE
1664:Fan
607:fan
372:LPG
352:air
342:in
338:or
99:by
2408::
953:.
775:.
771:.
749:.
728:.
455:.
426:.
378:,
354:,
326:A
61:.
1030:e
1023:t
1016:v
1001:.
982:.
961:.
935:.
916:.
897:.
878:.
859:.
840:.
821:.
789:.
753:.
708:.
330:(
309:)
303:(
291:)
285:(
280:)
276:(
258:.
228:)
222:(
217:)
213:(
199:.
166:)
160:(
155:)
151:(
141:·
134:·
127:·
120:·
93:.
68:)
64:(
23:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
