| 摘要 |
The invention relates to the conversion of a substantially conventional gas fired furnace utilizing two or more of the clam shell-type heat exchanger cells, which is modified by converting one cell to a final stage counterflow heat exchanger for the hot gases of combustion, which modification incorporates directing the gases of combustion from the fired cells in a counterflow path through the non-fired cell by utilizing a positive displacement fan and then exhausting the gases of combustion. The modification eliminates the need for positive venting, while substantially increasing the operational efficiency of the furnace unit. The normal flue gas temperature in this type of furnace will be about 450 DEG F., while with the modification, the temperature will be reduced to less than about 200 DEG F. and efficiency will be increased by greater than 10 percent.
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