December 2011: CAZ Techniques

CAZ Techniques

The CAZ or Combustion Appliance Zone and its testing by a Certified BA is probably the singular most valuable service the full scale home assessment provides. All combustion appliances need dilution air in order to ignite/burn fuels completely and efficiently. The requirements could be as low as 17 CFM for a condensing furnace to as high as 600 CFM for an open free burning fireplace.

Things that affect this needed air for combustion/draft are essentially those considered and evaluated during the CAZ test and ensuing worst case scenario. Understanding these forces in a large context is useful for all people involved within the Home Performance field because the work they do either directly or indirectly impacts them (or at some point could). The following is extracted by an article entitled “Ten trends that can spell trouble.” By John Tooley in a tech update reprinted from a summer issue of Good Cents Magazine:

1.      Tighter houses
2.      More ventfree and ventless fuel burners
3.      More exhaust fans
4.      Lower vent gas temperatures
5.      More forced air systems
6.      Fewer returns
7.      Higher air handler flows
8.      De-compartmentalization of assemblies
9.      More is better
10.    Home is where the office is


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