flues and windows.

Hi Everyone,

I was wondering if anyone has specifics about flue(and air intakes) positions(facing up, facing down), locations and distances from building openings, for hi efficiency furnaces.

Thank you,


They are slightly different for each manufactur and clearly identified in their installation manuals.

ICC Has a bunch of different spec on this and it also depends on if it is residental or commercal




See page 18

I found no screens too.


Screens on intakes or exhausts not a good idea. screen material on intake could result in hoar frost formation during sub zero conditions. Screen material not hardware cloth on the exhaust can restrict and reduce the vent gases where even though furnace may continue to run high carbon monoxide levels are produced.


Good point. It didn’t make it to my report, but I asked the client to chat with the HVAC guy(since the heat didn’t work they were going to chat) and ask about screens around a occupied area. See the deck and proximity, could have kids putting stuff in there.