Jim Katen Posted December 13, 2009 Report Share Posted December 13, 2009 Jim K.....Would you know where I can find detailed descriptions on furnace categories? Marc Here are the definitions from the 2006 IRC. VENTED GAS APPLIANCE CATEGORIES. Appliances that are categorized for the purpose of vent selection are classified into the following four categories: Category I. An appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent. Category II. An appliance that operates with a nonpositive vent static pressure and with a vent gas temperature that is capable of causing excessive condensate production in the vent. Category III. An appliance that operates with a positive vent static pressure and with a vent gas temperature that avoids excessive condensate production in the vent. Category IV. An appliance that operates with a positive vent static pressure and with a vent gas temperature that is capable of causing excessive condensate production in the vent. Category I appliances include gas furnaces that has draft hoods as well as the more modern fan-assisted furnaces. Category IV appliances include the high efficiency condensing furnaces that are so popular now. Category II and III appliances are very rare. I can't remember the last one that I saw of either type. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
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