Jim Wheeler 2012-12-14 03:47:10
High-efficiency furnace history During most of my lifetime, furnaces were just furnaces. The main difference was whether they were gas or oil. Oh, there were some minor efficiency claims, but most were in the range of 60% to 70%. Then, sometime in the early 1980s Lennox came up with its highefficiency “Pulse” furnace, which was probably one of the best-publicized new products in our industry since I can’t remember when. All of a sudden, our industry and the general public were aware of the fact most furnaces weren’t as efficient as they could be. Now understand the Lennox Pulse was not the type of high-efficiency furnace we are aware of today because it was an entirely new concept. Using the technology of the “buzz bombs” of World War II, rather than simply burning the gas as other furnaces do, it exploded it in tiny bursts that created a better energy transfer to the heat exchanger. It needed no exhaust fan since the bursts also took care of the venting. However, the Pulse was noisy and was eventually phased out in favor of the complicated furnaces we’ve all become so familiar with. Carrier put out a training program back then that I carried and taught with throughout our company’s territory. Carrier explained high-efficiency furnaces were nothing new since the company had manufactured a high-efficiency gas furnace toward the beginning of the 20th century. However, Carrier phased it out back then because it was problematic and the return on investment was too low to justify the added costs. What problems did Carrier foresee? The first was the deterioration of the heat exchangers (which many manufacturers later went on to experience) because the moisture created in the higher-efficiency combustion combined with acids from the combustion of the common chemicals found in most indoor air simply ate away the exchangers. Carrier also foresaw a problem with the venting capabilities of high-efficiency furnaces. Since the combustion air exiting the furnace is much cooler, it doesn’t warm the vent pipes or chimneys enough to allow them to draw properly. Land of make believe There is quite a difference between the legal situation of the early and later parts of the 20th century, because we now have all sorts of government agencies keeping an eye on us to make sure consumers are getting the highest efficiency out of everything, even if it’s just make believe. What am I talking about? It helps to realize that the 30% to 40% of the heat that used to be vented outdoors wasn’t really wasted. It was the engine that caused the vents and chimneys to draw. And since natural gas is one of our country’s most abundant and least-expensive forms of energy, this method didn’t usually cost too much to operate. What did we replace it with? Try electric motors and all sorts of controls and safety devices that raised the consumer cost of the product several times and probably didn’t save much actual energy once you consider the added electrical costs. Unfortunately, as with the foolish and needless phaseouts of our CFC and HCFC refrigerant gases (which don’t have to be vented into the atmosphere), it’s probably too late now to change things. As with the refrigerants, those who have paid the higher prices for their furnaces, the new venting schemes, the more expensive repair bills and all the failed secondary heat exchangers, there is an unwary and uninformed public. People like you and me. Jim Wheeler is an award-winning journalist who has worked in various positions in the HVACR industry since the early 1970s. His articles have been appearing every month since October of 1986. Contact him at firstname.lastname@example.org.
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