I have a coleman Evcon Gas Furnace Model 7956-856/D. It has an auxiliary combustion air intake (flex plastic pipe) running from the top of the furnace to a roof vent about 5’ down the roof slope from the furnace roof jack. It pulls in rainwater with the air & is causing a ceiling leak.
The furnace manual (page 8, figure 6) shows the roof jack higher than the roof ridge. The roof jack is a double wall pipe w/ an inner flue pipe and an outer combustion air tube. My roof jack is actually below the roof ridge. I am assuming this is so because the manufacturer of the double wide didn’t want anything above the ridge while it was on the road.
Question: If a 2’ length of double wall flue & combustion air pipe ( bringing the roof jack above the ridge) is added to the roof jack, will it draw enough combustion air through the roof jack to remove the auxiliary combustion air pipe?





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