Arkansas HVACR NewsMagazine January 2024

HVACR NewsMagazine January 2024

Tech News

Combustion Air Intake

80% induced-draft furnaces pull air in from around the unit (and are sometimes called “open combustion” furnaces). High -efficiency condensing furnaces have dedicated piping assemblies that bring combustion air in from the outdoors. This design allows you to have more control over the combustion air. It especially reduces the risk of contaminated combustion air due to VOCs, such as in nearby cleaning products or off-gassing paints. The combustion of a 90%+ furnace is “sealed” as a res ult. This difference is also important for home performance since 90%+ furnaces aren't using combustion air from the home that will need to be replaced by outside air or backdrafting through other appliances or exhaust. Sealed combustion is especially important in applications with encapsulated attics that have nowhere to draw combustion air from. That's why 90%+ gas furnaces are often seen in performance homes, even in the South. We interrupt this article by encouraging you to subscribe to Bryan ’ s website. We greatly appreciate his sharing articles for the NewsMagazine to reprint, but we only scratch the surface of what the HVAC School has to offer. From podcasts to YouTube to Tech Tips, you ’ ll enhance your knowledge and be connected to one of the most widely followed technical trainers for technicians in the country. Click on the picture or logo to learn more.

Drainage assembles that go straight to the outdoors may also pose problems in low ambient temperatures. The water can freeze into solid ice at the outlet, which will cause the drain to back up. Water management is one of the trickier parts of dealing with 90%+ furnaces, as the furnaces that preceded it never had to deal with it to the same degree. When in doubt, you can look up the manufacturer’s literature for help. Those manuals may have insulation guidelines and considerations based on your climate. For example, if the furnace is installed in an unconditioned space, such as an attic, the condensate drain may require heat tape to be applied.